Re: [time-nuts] OT Gel Cell question

[Ed Palmer]

I talked about this earlier today, but my message disappeared along with 
a second message.  Neither made it to the list at all.  So out of three 
messages sent, so far only one made it to the list.  Let's see if this 
one makes it.


All UPSs have a problem when trying to figure out what float voltage to 
use since the correct voltage varies with temperature, amongst other 
factors.  Some UPSs use a low-tech way to avoid the problem. They use a 
standard current-limited constant-voltage charger, but after float 
charging the battery for a couple of days they disconnect the charger.  
Too simple!  They then monitor the battery and recharge as necessary.  
This simple trick can double the life of the battery because it 
eliminates the continuous overcharging that uses up the very limited 
amount of water in the cell.


Ed

On 7/28/2014 7:03 PM, Brian, WA1ZMS wrote:

At the risk of adding fuel to the fire, I'd like to chime in and then will
go quiet.

Based on my first-hand day-job experience:
The consumer UPS units I have seen seem to run the float-voltage on Gel Cells
at the very high-end of the cell's spec.  The goal appears to be to get the
battery back to full terminal voltage and do it fast. That way the next AC 
mains drop out can utilize the full capacity of the Gel Cells.  The long term 
downside is that the cell would rather float at about a volt less or so and 
thus the life of the cells are reduced rather sharply.  Great for the UPS 
vendors; they get to sell replacement cells!

If one enters the 10kW and up category the game changes and the UPS vendors
take much care to use a multi-stage charger system to get bulk charge into the
cells, but not to float or "top off charge" the cells too much.

Enter the modern AGM-I and AGM-II cells and it becomes a grey area that I am
not well educated about.  I asked for hard data from the battery vendors, but
the answers were mixed at best.

Blunt answer I see is:
Do not treat flooded lead acid the same as Gel nor as AGM-I nor AGM-II.
And ALWAYS use temp sensors for best performance!

My 2 cents in the RF/Telecom World.

-Brian, WA1ZMS

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of paul swed
Sent: Monday, July 28, 2014 8:17 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] OT Gel Cell question

Elio
Oh man I have seen the amp hour magic also.
Thought maybe I was just getting older batteries. We have major home chains
in the US that batteries sit around for quite some time as measured by the
dust on them. So I was thinking that was the case.
Regards
Paul.



On Mon, Jul 28, 2014 at 6:50 PM, Elio Corbolante  wrote:


In my previous work I was developing UPSs: I can confirm that in the
last years the quality of the typical gel batteries has declined.
What once was 7Ah batteries now are sold as 9Ah ones!
And 5-6Ah ones are sold as 7Ah... :(
One of the best way to identify the "quality" of sealed batteries is
to weigh them: the heaviest have the highest capacity (and in general
are also the best because the producer didn't spare on materials).

_   Elio Corbolante.



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Re: [time-nuts] OT Gel Cell question

[Charles Steinmetz]

Brooke wrote:


It turns out that "Made in China" does not in and of itself mean inferior.


I did not say that it did -- please actually read what you are 
replying to.  Here is what I said:


These manufacturers are capable of designing and constructing 
first-quality products, but the batteries that are commonly 
available in the US are made for brands that ask for the cheapest 
batteries possible.


"Brands" here means distribution companies (many are US companies, 
but not all) that order batteries to contracted spec from the OEM and 
sell them in the US (or wherever) under their own brand.  PowerSonic 
(which you mention by name) is one.  Actually, pretty much anyone who 
markets SLAs in the US is one.


But there may be an unauthorized night shift that uses the same raw 
materials and makes a product without any QA.  It may or may not be 
as good as the "official" product.


Oh, please.  OEMs make what buyers order.  It's got nothing to do 
with "unauthorized night shifts" or "shadow factories," it all 
depends on what the buyer (the "brand") orders and is willing to 
check for when it inspects the received products.  When you press an 
OEM for cheaper and cheaper products, it cuts more and more corners, 
sometimes including corners that the contract specifies shall NOT be 
cut (if you push a contractor to pinch every penny, you may get 
product that does not comply with the contract).  This is infamously 
true of Chinese electronics OEMs, but applies generally to OEMs, 
including many in the US and EU.


it may be that a battery with the Power Sonic label is a quality 
battery even if it does have a "Made in China" sticker.


PowerSonic batteries are, in fact, some of the better SLA batteries 
available in the US today (although they are a far cry from the best 
that can be made).  Back in March I wrote this on the volt-nuts list:


Also, I strongly advise against using the cheapest batteries you 
can get.  Those will invariably be very low quality batteries, 
which will fail prematurely.   There is a huge difference in 
quality from good SLAs to poor ones.  I have found that PowerSonic 
SLA batteries give good service in the 732A (about $35 each).


There are all-black batteries, sold under the "AJC" brand and many 
others, that are unmitigated crap.


Best regards,

Charles



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Re: [time-nuts] OT Gel Cell question

[Brian, WA1ZMS]

At the risk of adding fuel to the fire, I'd like to chime in and then will
go quiet.

Based on my first-hand day-job experience:
The consumer UPS units I have seen seem to run the float-voltage on Gel
Cells
at the very high-end of the cell's spec.  The goal appears to be to get the
battery
back to full terminal voltage and do it fast. That way the next AC mains
drop out
can utilize the full capacity of the Gel Cells.  The long term downside is
that the
cell would rather float at about a volt less or so and thus the life of the
cells are
reduced rather sharply.  Great for the UPS vendors; they get to sell
replacement
cells!

If one enters the 10kW and up category the game changes and the UPS vendors
take
much care to use a multi-stage charger system to get bulk charge into the
cells, but
not to float or "top off charge" the cells too much.

Enter the modern AGM-I and AGM-II cells and it becomes a grey area that I am
not
well educated about.  I asked for hard data from the battery vendors, but
the answers
were mixed at best.

Blunt answer I see is:
Do not treat flooded lead acid the same as Gel nor as AGM-I nor AGM-II.
And ALWAYS use temp sensors for best performance!

My 2 cents in the RF/Telecom World.

-Brian, WA1ZMS

-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of paul swed
Sent: Monday, July 28, 2014 8:17 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] OT Gel Cell question

Elio
Oh man I have seen the amp hour magic also.
Thought maybe I was just getting older batteries. We have major home chains
in the US that batteries sit around for quite some time as measured by the
dust on them. So I was thinking that was the case.
Regards
Paul.



On Mon, Jul 28, 2014 at 6:50 PM, Elio Corbolante  wrote:

> In my previous work I was developing UPSs: I can confirm that in the 
> last years the quality of the typical gel batteries has declined.
> What once was 7Ah batteries now are sold as 9Ah ones!
> And 5-6Ah ones are sold as 7Ah... :(
> One of the best way to identify the "quality" of sealed batteries is 
> to weigh them: the heaviest have the highest capacity (and in general 
> are also the best because the producer didn't spare on materials).
>
> _   Elio Corbolante.
> ___
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Re: [time-nuts] OT Gel Cell question

[paul swed]

Elio
Oh man I have seen the amp hour magic also.
Thought maybe I was just getting older batteries. We have major home chains
in the US that batteries sit around for quite some time as measured by the
dust on them. So I was thinking that was the case.
Regards
Paul.



On Mon, Jul 28, 2014 at 6:50 PM, Elio Corbolante  wrote:

> In my previous work I was developing UPSs: I can confirm that in the last
> years the quality of the typical gel batteries has declined.
> What once was 7Ah batteries now are sold as 9Ah ones!
> And 5-6Ah ones are sold as 7Ah... :(
> One of the best way to identify the "quality" of sealed batteries is to
> weigh them: the heaviest have the highest capacity (and in general are also
> the best because the producer didn't spare on materials).
>
> _   Elio Corbolante.
> ___
> time-nuts mailing list -- time-nuts@febo.com
> To unsubscribe, go to
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Re: [time-nuts] OT Gel Cell question

[Elio Corbolante]

In my previous work I was developing UPSs: I can confirm that in the last
years the quality of the typical gel batteries has declined.
What once was 7Ah batteries now are sold as 9Ah ones!
And 5-6Ah ones are sold as 7Ah... :(
One of the best way to identify the "quality" of sealed batteries is to
weigh them: the heaviest have the highest capacity (and in general are also
the best because the producer didn't spare on materials).

_   Elio Corbolante.
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Re: [time-nuts] OT Gel Cell question

[Charles Steinmetz]

Paul wrote:

Stay away from hamfest/flea market batteries. They are almost always 
bad and nothing really revives them. Pay the money and make sure you 
get a recent build date.


Also, know that there is a huge range of quality represented by the 
batteries available on the market.  Unfortunately, almost all 
batteries these days come out of just a few factories in 
China.  These manufacturers are capable of designing and constructing 
first-quality products, but the batteries that are commonly available 
in the US are made for brands that ask for the cheapest batteries 
possible.  So you need to find a brand that aims higher and actually 
does its own quality control.


And do not be misled by what has become an almost universal 
bait-and-switch technique:  You find a link that says "GENUINE 
[brand] battery!!" and when you follow the link the page says 
"[BRAND] battery" prominently at the top but when you scroll down you 
find in tiny print that the battery for sale is "compatible with 
GENUINE [BRAND] battery" or is a "GENUINE [BRAND] replacement 
battery" and is actually the cheapest, most awful POS battery made.


Panasonic SLAs are by far the best I've used (even the ones made in 
China), but I haven't found any for sale in the US for a few years 
now.  If anybody knows of a source, please share.


Best regards,

Charles



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Re: [time-nuts] OT Gel Cell question

[Brooke Clarke]

Hi Charles:

It turns out that "Made in China" does not in and of itself mean inferior.  
There's a spectrum of quality levels.

For example there are some very high end companies in China and during working shifts they turn out products that are 
very bit as good as any you would find.


But there may be an unauthorized night shift that uses the same raw materials and makes a product without any QA.  It 
may or may not be as good as the "official" product.  Products from the reject bin may make their way to the open market.


There may be a shadow factory down the road where workers trained at the official factory make products with different 
materials and no QA.


There may be a factory anywhere with untrained workers making a sort of 
lookalike product.

From three feet away I doubt anyone can tell the difference.

So in answer to your question, it may be that a battery with the Power Sonic label is a quality battery even if it does 
have a "Made in China" sticker.


Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html

Charles Steinmetz wrote:

Paul wrote:

Stay away from hamfest/flea market batteries. They are almost always bad and nothing really revives them. Pay the 
money and make sure you get a recent build date.


Also, know that there is a huge range of quality represented by the batteries available on the market.  Unfortunately, 
almost all batteries these days come out of just a few factories in China. These manufacturers are capable of 
designing and constructing first-quality products, but the batteries that are commonly available in the US are made 
for brands that ask for the cheapest batteries possible.  So you need to find a brand that aims higher and actually 
does its own quality control.


And do not be misled by what has become an almost universal bait-and-switch technique:  You find a link that says 
"GENUINE [brand] battery!!" and when you follow the link the page says "[BRAND] battery" prominently at the top but 
when you scroll down you find in tiny print that the battery for sale is "compatible with GENUINE [BRAND] battery" or 
is a "GENUINE [BRAND] replacement battery" and is actually the cheapest, most awful POS battery made.


Panasonic SLAs are by far the best I've used (even the ones made in China), but I haven't found any for sale in the US 
for a few years now.  If anybody knows of a source, please share.


Best regards,

Charles



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Re: [time-nuts] OT Gel Cell question

[paul swed]

Clearly under an abused situation I have seen cracked/fractured gel cells
as an example. Due to I speculate pretty much the poorest of charge design.

This includes powdery stuff, corrosion and metal that has been etched from
what at sometime was a liquid.
Almost the first thing I check is the batteries on test gear I manage to
pickup.
Regards
Paul
WB8TSL


On Mon, Jul 28, 2014 at 3:18 PM, Chuck Harris  wrote:

> That said, I have never seen a gel cell, or a glass mat lead acid battery
> leak acid, or emit fumes.  I'm not saying it can't happen, just that in
> all of my battery work, I haven't seen it... [unlike with nicads, where I
> think something is wrong when I don't see leakage.]
>
> The seal is something they take very seriously, and is typically some
> form of elasomeric plastic/rubber.  Even the seal between the plastic
> case and the faston tabs is flexible.
>
> If the battery has a cell that is seriously overcharging, due to a short
> in another cell, it will out gas hydrogen and oxygen due to the
> electrolytic
> breakdown of the water in the electrolyte.  Probably better that it do that
> than to blow up.
>
> -Chuck Harris
>
> Alexander Pummer wrote:
>
>> as long as it is not a gals/ceramic seal, there is no way to stop
>> sulfuric acid to
>> get out from the cell, just imagine the dilatation diffrence between
>> plastic and
>> metal...
>> 73
>> Alex
>>
>> On 7/28/2014 10:12 AM, Ed Palmer wrote:
>>
>>> As I understand it, the only time that any sealed lead acid battery will
>>> vent is in
>>> the case of gross overcharging.  The battery is designed so that normal
>>> charge
>>> rates and correct float voltage will result in recombination of any
>>> hydrogen and
>>> oxygen produced. Was there a fault in the charging circuit or perhaps,
>>> the charging
>>> circuit didn't have proper temperature compensation of the charge
>>> voltage?
>>>
>>> Ed
>>>
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Re: [time-nuts] OT Gel Cell question

[Brooke Clarke]

Hi Ed:

I don't know.  When I got the unit the batteries had been removed.  The power supply consists of two 723 based voltage 
regulator curcuits the first to drop the line voltage to about 20 V (float charging 3 each 6 V Gell Cells) and the 
second 723 circuit to take in battery voltage and supply a lower voltage to run the unit.


The key problem was the short distance between the batteries and the hot oven.  Maybe the oven was also heating the 
batteries. Something to keep in mind today.


Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html

Ed Palmer wrote:
As I understand it, the only time that any sealed lead acid battery will vent is in the case of gross overcharging.  
The battery is designed so that normal charge rates and correct float voltage will result in recombination of any 
hydrogen and oxygen produced. Was there a fault in the charging circuit or perhaps, the charging circuit didn't have 
proper temperature compensation of the charge voltage?


Ed

On 7/28/2014 10:56 AM, Brooke Clarke wrote:

Hi:

Using lead acid batteries and a precision frequency standard is not a good 
thing if they are too close together.

A number of decades ago (before the Time Nuts or the internet) I was able to purchase a rack mount Gibbs 5 MHz double 
oven frequency standard that used a very nice Bliley glass tube crystal because it was not as precise as is was 
supposed to be. It used GelCell backup batteries that were physically in the same rack chassis as the oven.  The 
fumes from the batteries when charging etched some traces off the PCB inside the oven defeating the temperature 
control but leaving the oscillator. It took a long time to reverse engineer and repair it.  I've added a photo of the 
cord wood construction of the cylindrical oscillator.  The core of the cylinder holds the glass bottle crystal and 
the glass piston coarse tuning capacitor, surrounded by the first heater, circuitry for the oscillator and dual 
temperature control circuits on ring shaped boards.  These fit inside a cylindrical cavity which is the outer oven.  
I've added a photo of the inner assembly at:

http://prc68.com/I/office_equip.html

Have Fun,

Brooke Clarke


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Re: [time-nuts] OT Gel Cell question

[paul swed]

I think we crossed some wires here. Pun intended.
Brook said the fumes ate away the traces and he is right. On a flooded cell
batteries such as he describes the fumes are nasty. Its quite normal on a
flooded cell to purposely drive them into overcharge. This is known as
equalizing. I have to do that on my 2000 Lbs battery from time to time.
On Gel Cells that is a very bad process and you don't do it because they
will vent.
My only wisdom is this. Stay away from hamfest/flea market batteries. They
are almost always bad and nothing really revives them. Pay the money and
make sure you get a recent build date.
Regards
Paul.
WB8TSL


On Mon, Jul 28, 2014 at 1:44 PM, Alexander Pummer  wrote:

> as long as it is not a gals/ceramic seal, there is no way to stop sulfuric
> acid to get out from the cell, just imagine the dilatation diffrence
> between plastic and metal...
> 73
> Alex
>
>
> On 7/28/2014 10:12 AM, Ed Palmer wrote:
>
>> As I understand it, the only time that any sealed lead acid battery will
>> vent is in the case of gross overcharging.  The battery is designed so that
>> normal charge rates and correct float voltage will result in recombination
>> of any hydrogen and oxygen produced. Was there a fault in the charging
>> circuit or perhaps, the charging circuit didn't have proper temperature
>> compensation of the charge voltage?
>>
>> Ed
>>
>> On 7/28/2014 10:56 AM, Brooke Clarke wrote:
>>
>>> Hi:
>>>
>>> Using lead acid batteries and a precision frequency standard is not a
>>> good thing if they are too close together.
>>>
>>> A number of decades ago (before the Time Nuts or the internet) I was
>>> able to purchase a rack mount Gibbs 5 MHz double oven frequency standard
>>> that used a very nice Bliley glass tube crystal because it was not as
>>> precise as is was supposed to be. It used GelCell backup batteries that
>>> were physically in the same rack chassis as the oven.  The fumes from the
>>> batteries when charging etched some traces off the PCB inside the oven
>>> defeating the temperature control but leaving the oscillator. It took a
>>> long time to reverse engineer and repair it.  I've added a photo of the
>>> cord wood construction of the cylindrical oscillator.  The core of the
>>> cylinder holds the glass bottle crystal and the glass piston coarse tuning
>>> capacitor, surrounded by the first heater, circuitry for the oscillator and
>>> dual temperature control circuits on ring shaped boards.  These fit inside
>>> a cylindrical cavity which is the outer oven.  I've added a photo of the
>>> inner assembly at:
>>> http://prc68.com/I/office_equip.html
>>>
>>> Have Fun,
>>>
>>> Brooke Clarke
>>>
>>
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>> mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
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Re: [time-nuts] OT Gel Cell question

[Chuck Harris]

That said, I have never seen a gel cell, or a glass mat lead acid battery
leak acid, or emit fumes.  I'm not saying it can't happen, just that in
all of my battery work, I haven't seen it... [unlike with nicads, where I
think something is wrong when I don't see leakage.]

The seal is something they take very seriously, and is typically some
form of elasomeric plastic/rubber.  Even the seal between the plastic
case and the faston tabs is flexible.

If the battery has a cell that is seriously overcharging, due to a short
in another cell, it will out gas hydrogen and oxygen due to the electrolytic
breakdown of the water in the electrolyte.  Probably better that it do that
than to blow up.

-Chuck Harris

Alexander Pummer wrote:

as long as it is not a gals/ceramic seal, there is no way to stop sulfuric acid 
to
get out from the cell, just imagine the dilatation diffrence between plastic and
metal...
73
Alex

On 7/28/2014 10:12 AM, Ed Palmer wrote:

As I understand it, the only time that any sealed lead acid battery will vent 
is in
the case of gross overcharging.  The battery is designed so that normal charge
rates and correct float voltage will result in recombination of any hydrogen and
oxygen produced. Was there a fault in the charging circuit or perhaps, the 
charging
circuit didn't have proper temperature compensation of the charge voltage?

Ed

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Re: [time-nuts] OT Gel Cell question

[Alexander Pummer]

as long as it is not a gals/ceramic seal, there is no way to stop 
sulfuric acid to get out from the cell, just imagine the dilatation 
diffrence between plastic and metal...

73
Alex

On 7/28/2014 10:12 AM, Ed Palmer wrote:
As I understand it, the only time that any sealed lead acid battery 
will vent is in the case of gross overcharging.  The battery is 
designed so that normal charge rates and correct float voltage will 
result in recombination of any hydrogen and oxygen produced. Was there 
a fault in the charging circuit or perhaps, the charging circuit 
didn't have proper temperature compensation of the charge voltage?


Ed

On 7/28/2014 10:56 AM, Brooke Clarke wrote:

Hi:

Using lead acid batteries and a precision frequency standard is not a 
good thing if they are too close together.


A number of decades ago (before the Time Nuts or the internet) I was 
able to purchase a rack mount Gibbs 5 MHz double oven frequency 
standard that used a very nice Bliley glass tube crystal because it 
was not as precise as is was supposed to be. It used GelCell backup 
batteries that were physically in the same rack chassis as the oven.  
The fumes from the batteries when charging etched some traces off the 
PCB inside the oven defeating the temperature control but leaving the 
oscillator. It took a long time to reverse engineer and repair it.  
I've added a photo of the cord wood construction of the cylindrical 
oscillator.  The core of the cylinder holds the glass bottle crystal 
and the glass piston coarse tuning capacitor, surrounded by the first 
heater, circuitry for the oscillator and dual temperature control 
circuits on ring shaped boards.  These fit inside a cylindrical 
cavity which is the outer oven.  I've added a photo of the inner 
assembly at:

http://prc68.com/I/office_equip.html

Have Fun,

Brooke Clarke


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Re: [time-nuts] OT Gel Cell question

[Ed Palmer]

As I understand it, the only time that any sealed lead acid battery will 
vent is in the case of gross overcharging.  The battery is designed so 
that normal charge rates and correct float voltage will result in 
recombination of any hydrogen and oxygen produced.  Was there a fault in 
the charging circuit or perhaps, the charging circuit didn't have proper 
temperature compensation of the charge voltage?


Ed

On 7/28/2014 10:56 AM, Brooke Clarke wrote:

Hi:

Using lead acid batteries and a precision frequency standard is not a 
good thing if they are too close together.


A number of decades ago (before the Time Nuts or the internet) I was 
able to purchase a rack mount Gibbs 5 MHz double oven frequency 
standard that used a very nice Bliley glass tube crystal because it 
was not as precise as is was supposed to be.  It used GelCell backup 
batteries that were physically in the same rack chassis as the oven.  
The fumes from the batteries when charging etched some traces off the 
PCB inside the oven defeating the temperature control but leaving the 
oscillator.  It took a long time to reverse engineer and repair it.  
I've added a photo of the cord wood construction of the cylindrical 
oscillator.  The core of the cylinder holds the glass bottle crystal 
and the glass piston coarse tuning capacitor, surrounded by the first 
heater, circuitry for the oscillator and dual temperature control 
circuits on ring shaped boards.  These fit inside a cylindrical cavity 
which is the outer oven.  I've added a photo of the inner assembly at:

http://prc68.com/I/office_equip.html

Have Fun,

Brooke Clarke


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Re: [time-nuts] OT Gel Cell question

[Richard (Rick) Karlquist]

On 7/28/2014 1:12 AM, David C. Partridge wrote:

Back to time related discussions please.

Thanks
Dave



I worked on cesium standards (5071A)
at HP/Agilent with Len Cutler of flying clock
fame.  You better believe that batteries are
time related.  We jumped through all sorts of
hoops to get the 5071A power consumption down
to a few dozen watts so it could run off of
batteries.  The other reason for minimizing
power consumption was to avoid fans.  HP also
used to sell auxiliary battery systems in
case the user needed more battery run time
than the internal battery was capable of.

Rick Karlquist N6RK


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Re: [time-nuts] OT Gel Cell question

[Brooke Clarke]

Hi:

Using lead acid batteries and a precision frequency standard is not a good 
thing if they are too close together.

A number of decades ago (before the Time Nuts or the internet) I was able to purchase a rack mount Gibbs 5 MHz double 
oven frequency standard that used a very nice Bliley glass tube crystal because it was not as precise as is was supposed 
to be.  It used GelCell backup batteries that were physically in the same rack chassis as the oven.  The fumes from the 
batteries when charging etched some traces off the PCB inside the oven defeating the temperature control but leaving the 
oscillator.  It took a long time to reverse engineer and repair it.  I've added a photo of the cord wood construction of 
the cylindrical oscillator.  The core of the cylinder holds the glass bottle crystal and the glass piston coarse tuning 
capacitor, surrounded by the first heater, circuitry for the oscillator and dual temperature control circuits on ring 
shaped boards.  These fit inside a cylindrical cavity which is the outer oven.  I've added a photo of the inner assembly 
at:

http://prc68.com/I/office_equip.html

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html


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Re: [time-nuts] OT Gel Cell question

[John Allen]

That's for sure.  Lead Acid batteries run everything except where power
density is critical.
We all need to know as much as possible about them.  I thought that I knew a
lot, but the dialogue on this list has raised my understanding
significantly.

Thanks to all who have contributed so far.  A treasure trove of information.

Regards, John K1AE
 
Sent: Monday, July 28, 2014 8:39 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] OT Gel Cell question

Ever use batteries to back up your time toys David?

I would bet they were lead acid.  More that a few folks on this group are
using lead acid to run such things.  Discussions of charging, discharging,
and care of batteries is just as apropos, in my opinion, as discussions on
which coax to use, or which receiver to use to run your GPSDO... Or for that
matter which SBC to use to run your favorite time hack.

It is all part of the infrastructure necessary to make the study of fine
time possible.

-Chuck Harris

David C. Partridge wrote:
> Back to time related discussions please.
>
> Thanks
> Dave

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Re: [time-nuts] OT Gel Cell question

[Chuck Harris]

Ever use batteries to back up your time toys David?

I would bet they were lead acid.  More that a few
folks on this group are using lead acid to run such
things.  Discussions of charging, discharging, and
care of batteries is just as apropos, in my opinion,
as discussions on which coax to use, or which receiver
to use to run your GPSDO... Or for that matter which
SBC to use to run your favorite time hack.

It is all part of the infrastructure necessary to
make the study of fine time possible.

-Chuck Harris

David C. Partridge wrote:

Back to time related discussions please.

Thanks
Dave

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Re: [time-nuts] OT Gel Cell question

[Chuck Harris]

Neville,

Sorry, I don't agree.  There is plenty of ion exchange
capability in the "water" left over from a totally dead
lead acid battery to corrode the skin off of your hands.

I have never found one where the specific gravity of the
water reached 1.0.  Even a couple of drops of acid in
the water would be sufficient for significant current to
flow.

However, it still won't take any charge.  Not even a
milliamp at 15V.

The reason it won't charge is the lead sulfate covering the
lead plates is a very good insulator.

And, to quote my old college chemistry book:

- General Chemistry, 4th Edition, Nebergall, Schmidt and
  Holtzclaw, DC Heath and Company, 1972. p862:

"Lead sulfate PbSO4 is formed by ionic combinations, and
is insoluble in water but readily dissolved by solutions
containing an excess of alkali or acetate ions..."

I stand by my statements.

-Chuck Harris



Neville Michie wrote:

To clear up the point,
lead sulphate is very much more soluble in water than sulphuric acid,
and when batteries get flat all the sulphuric acid is reacted leaving
only water. That is why no current will flow when trying to charge them.
It is all well documented, see:
Vinal.G.W. (1945) Storage Batteries,
John Wiley & Sons, Inc. New York Pp. 464

The sulphate is more soluble at higher temperature, and the daily thermal 
cycling
of an uncharged battery adds to the damage.

There are many popular myths and partial truths abroad, largely, I guess,
because the study of batteries is in few current engineering courses.
Magic additives to restore dead batteries have been around for 100 years,
but none of them are effective.
The only trick I have seen was an old guy who heated car batteries in an oven,
I never found out how long or how hot, he made a living reselling them
with a money back six months guarantee.
cheers,
Neville Michie

On 28/07/2014, at 1:59 PM, Chuck Harris wrote:


A small disagreement on a couple of points

Lead sulfate does not dissolve (in the normal battery chemistry),
and does not go all over the place. It forms at the lead and the
lead oxide plates, during discharge, and there it stays
(unless it breaks off) until you charge the cell.  It is the
electrolytic cell action that allows the lead sulfate to be
converted back into lead metal, lead oxide, and sulfuric acid.

Everyone wishes lead sulfate could be dissolved safely, as this
could be a way of recovering batteries that have been overly
discharged.

Lots of snake oil remedies have been created that tout to do just
that... things like lime juice, ETDA, adding more sulfuric acid...
AFAIK, none of them really work.

Shorting in a wet (flooded) lead acid battery happens because the
charging/discharging action causes the creation and destruction of
lead sulfate, and because the lead sulfate is less dense than the
lead and lead oxide it replaces, it flexes the plates.  The flexing
causes some of the lead sulfate to break free of the plates, and
drop to the bottom of the cell.  Because energy density is
important in a lead acid battery, the manufacturer wastes as little
space in the battery case as possible by putting the plates as
close to the bottom of the battery "jar" as it dares.  This allows
the lead flakes to build up on the bottom until they reach the
level of the plates and short them out.

The gel cells, and glass mat cells short because the lead dendrites
that sometimes grow as a result of charging/discharging, pierce the
separator and short the plates directly.

-Chuck Harris

Neville Michie wrote:


Hi,

Lead acid cells have lead supports carrying lead oxide and lead metal active 
material
in an electrolyte of sulphuric acid.
When they discharge, the sulphuric acid electrolyte is reacted with the oxides 
and metal
to form lead sulphate and the concentration of the acid falls, that is why 
garages
used to check batteries with a hydrometer to measure the electrolyte 
concentration.
At the same time the terminal voltage drops and the internal resistance rises,
when the concentration of the electrolyte gets very low, the lead sulphate 
becomes
soluble and will re-deposit all over the battery. With gel cells the 
electrolyte can
be completely absorbed making the battery resistance infinitely high.
If you can get some current to flow, you may be lucky enough to get the battery 
to
reform some electrolyte, conduct some more, and eventually charge.
However, when flat the lead sulphate dissolves and redeposits all over the 
battery,
and when recharged will convert back to lead and lead oxide, often most 
inconveniently
bridging the plates to a short circuit.
The lesson is to not let the battery ever get flat.

Lead acid batteries have some very good features.
The terminal voltage rises as the concentration of the acid increases. So a 
constant voltage will
charge a cell, and current stops flowing when the electrolyte reaches its 
proper concentration.
The catch is, when you have a battery of several cells, if one cell gets weak, 
the others will b

Re: [time-nuts] OT Gel Cell question

[David C. Partridge]

Back to time related discussions please. 

Thanks
Dave

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Re: [time-nuts] OT Gel Cell question

[Neville Michie]

To clear up the point,
lead sulphate is very much more soluble in water than sulphuric acid,
and when batteries get flat all the sulphuric acid is reacted leaving
only water. That is why no current will flow when trying to charge them.
It is all well documented, see: 
Vinal.G.W. (1945) Storage Batteries,
John Wiley & Sons, Inc. New York Pp. 464

The sulphate is more soluble at higher temperature, and the daily thermal 
cycling
of an uncharged battery adds to the damage.

There are many popular myths and partial truths abroad, largely, I guess,
because the study of batteries is in few current engineering courses.
Magic additives to restore dead batteries have been around for 100 years,
but none of them are effective.
The only trick I have seen was an old guy who heated car batteries in an oven,
I never found out how long or how hot, he made a living reselling them 
with a money back six months guarantee.
cheers, 
Neville Michie

On 28/07/2014, at 1:59 PM, Chuck Harris wrote:

> A small disagreement on a couple of points
> 
> Lead sulfate does not dissolve (in the normal battery chemistry),
> and does not go all over the place. It forms at the lead and the
> lead oxide plates, during discharge, and there it stays
> (unless it breaks off) until you charge the cell.  It is the
> electrolytic cell action that allows the lead sulfate to be
> converted back into lead metal, lead oxide, and sulfuric acid.
> 
> Everyone wishes lead sulfate could be dissolved safely, as this
> could be a way of recovering batteries that have been overly
> discharged.
> 
> Lots of snake oil remedies have been created that tout to do just
> that... things like lime juice, ETDA, adding more sulfuric acid...
> AFAIK, none of them really work.
> 
> Shorting in a wet (flooded) lead acid battery happens because the
> charging/discharging action causes the creation and destruction of
> lead sulfate, and because the lead sulfate is less dense than the
> lead and lead oxide it replaces, it flexes the plates.  The flexing
> causes some of the lead sulfate to break free of the plates, and
> drop to the bottom of the cell.  Because energy density is
> important in a lead acid battery, the manufacturer wastes as little
> space in the battery case as possible by putting the plates as
> close to the bottom of the battery "jar" as it dares.  This allows
> the lead flakes to build up on the bottom until they reach the
> level of the plates and short them out.
> 
> The gel cells, and glass mat cells short because the lead dendrites
> that sometimes grow as a result of charging/discharging, pierce the
> separator and short the plates directly.
> 
> -Chuck Harris
> 
> Neville Michie wrote:
>> 
>> Hi,
>> 
>> Lead acid cells have lead supports carrying lead oxide and lead metal active 
>> material
>> in an electrolyte of sulphuric acid.
>> When they discharge, the sulphuric acid electrolyte is reacted with the 
>> oxides and metal
>> to form lead sulphate and the concentration of the acid falls, that is why 
>> garages
>> used to check batteries with a hydrometer to measure the electrolyte 
>> concentration.
>> At the same time the terminal voltage drops and the internal resistance 
>> rises,
>> when the concentration of the electrolyte gets very low, the lead sulphate 
>> becomes
>> soluble and will re-deposit all over the battery. With gel cells the 
>> electrolyte can
>> be completely absorbed making the battery resistance infinitely high.
>> If you can get some current to flow, you may be lucky enough to get the 
>> battery to
>> reform some electrolyte, conduct some more, and eventually charge.
>> However, when flat the lead sulphate dissolves and redeposits all over the 
>> battery,
>> and when recharged will convert back to lead and lead oxide, often most 
>> inconveniently
>> bridging the plates to a short circuit.
>> The lesson is to not let the battery ever get flat.
>> 
>> Lead acid batteries have some very good features.
>> The terminal voltage rises as the concentration of the acid increases. So a 
>> constant voltage will
>> charge a cell, and current stops flowing when the electrolyte reaches its 
>> proper concentration.
>> The catch is, when you have a battery of several cells, if one cell gets 
>> weak, the others will be overcharged
>> causing gassing and over concentration of the electrolyte.
>> There is a judicious voltage that causes an acceptably low rate of gassing
>> (the oxygen hydrogen catalytically recombining) that will keep the charges 
>> of cells equalised.
>> But it only takes one total discharge event to cause enough leakage in one 
>> cell
>> to bring about failure.
>> 
>> Lead acid batteries are also environmentally excellent.
>> They consist of nothing but pure lead and sulphuric acid and water.
>> Sulphuric acid is not volatile so you can make batteries out of old batteries
>> forever, recycling the acid, lead and water.
>> If made on a large scale they are also very efficient (99.9% +) electrically.
>> 
>> cheers

Re: [time-nuts] OT Gel Cell question

[Chuck Harris]

A small disagreement on a couple of points

Lead sulfate does not dissolve (in the normal battery chemistry),
and does not go all over the place. It forms at the lead and the
lead oxide plates, during discharge, and there it stays
(unless it breaks off) until you charge the cell.  It is the
electrolytic cell action that allows the lead sulfate to be
converted back into lead metal, lead oxide, and sulfuric acid.

Everyone wishes lead sulfate could be dissolved safely, as this
could be a way of recovering batteries that have been overly
discharged.

Lots of snake oil remedies have been created that tout to do just
that... things like lime juice, ETDA, adding more sulfuric acid...
AFAIK, none of them really work.

Shorting in a wet (flooded) lead acid battery happens because the
charging/discharging action causes the creation and destruction of
lead sulfate, and because the lead sulfate is less dense than the
lead and lead oxide it replaces, it flexes the plates.  The flexing
causes some of the lead sulfate to break free of the plates, and
drop to the bottom of the cell.  Because energy density is
important in a lead acid battery, the manufacturer wastes as little
space in the battery case as possible by putting the plates as
close to the bottom of the battery "jar" as it dares.  This allows
the lead flakes to build up on the bottom until they reach the
level of the plates and short them out.

The gel cells, and glass mat cells short because the lead dendrites
that sometimes grow as a result of charging/discharging, pierce the
separator and short the plates directly.

-Chuck Harris

Neville Michie wrote:


Hi,

Lead acid cells have lead supports carrying lead oxide and lead metal active 
material
in an electrolyte of sulphuric acid.
When they discharge, the sulphuric acid electrolyte is reacted with the oxides 
and metal
to form lead sulphate and the concentration of the acid falls, that is why 
garages
used to check batteries with a hydrometer to measure the electrolyte 
concentration.
At the same time the terminal voltage drops and the internal resistance rises,
when the concentration of the electrolyte gets very low, the lead sulphate 
becomes
soluble and will re-deposit all over the battery. With gel cells the 
electrolyte can
be completely absorbed making the battery resistance infinitely high.
If you can get some current to flow, you may be lucky enough to get the battery 
to
reform some electrolyte, conduct some more, and eventually charge.
However, when flat the lead sulphate dissolves and redeposits all over the 
battery,
and when recharged will convert back to lead and lead oxide, often most 
inconveniently
bridging the plates to a short circuit.
The lesson is to not let the battery ever get flat.

Lead acid batteries have some very good features.
The terminal voltage rises as the concentration of the acid increases. So a 
constant voltage will
charge a cell, and current stops flowing when the electrolyte reaches its 
proper concentration.
The catch is, when you have a battery of several cells, if one cell gets weak, 
the others will be overcharged
causing gassing and over concentration of the electrolyte.
There is a judicious voltage that causes an acceptably low rate of gassing
(the oxygen hydrogen catalytically recombining) that will keep the charges of 
cells equalised.
But it only takes one total discharge event to cause enough leakage in one cell
to bring about failure.

Lead acid batteries are also environmentally excellent.
They consist of nothing but pure lead and sulphuric acid and water.
Sulphuric acid is not volatile so you can make batteries out of old batteries
forever, recycling the acid, lead and water.
If made on a large scale they are also very efficient (99.9% +) electrically.

cheers,
Neville Michie
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Re: [time-nuts] OT Gel Cell question

[DaveH]

A minor nit

The self-discharge rate is pretty high (20 to 40% per month) and the
charging is not as efficient.

Power density is pretty bad too.

For forklift operation this is not a problem as weight is a good thing, they
are topped off every night and the power used to run a forklift is minimal
given the overall consumption of an average factory.

Wikipedia has a nice comparison

http://en.wikipedia.org/wiki/Nickel%E2%80%93iron_battery

http://en.wikipedia.org/wiki/Lead%E2%80%93acid_battery

Here is a vendor:

http://ironedison.com/

Dave

> -Original Message-
> From: time-nuts-boun...@febo.com 
> [mailto:time-nuts-boun...@febo.com] On Behalf Of Alex Pummer
> Sent: Sunday, July 27, 2014 15:48
> To: time-nuts@febo.com
> Subject: Re: [time-nuts] OT Gel Cell question
> 
> it is not a high performance battery but extremely robust, see there 
> http://www.nickel-iron-battery.com/
> it is no polluting, it could be shorted out overcharged
> if you are lucky and find one old forklift with Edison 
> Battery -- which 
> was built some fifty years egoit will out last you too
> you could charge in current mode, C/10, 2C nothing will happen just 
> replace evaporated water in the elctrtrolyt which is KOH
> 73
> Alex
> 
> 
> On 7/27/2014 2:41 PM, Chuck Harris wrote:
> > I too have spent a lot of time charging batteries using different 
> > methods on
> > various chemistries.  Once upon a time, I build a number of 
> suitcase 
> > battery
> > chargers for the US Army that allowed them to charge every portable 
> > secondary
> > battery type that they had in inventory... SLA, AgO, NiCD, NIMH,
> > LiIon...  I proved a concept, and someone else got to make 
> all of the 
> > money
> > off of it when the ARMY shopped my prototypes around... but 
> I digress.
> >
> > When you try to charge a sulfated lead acid cell, you can 
> think of the 
> > cell
> > as being a bunch of little parallel lead acid microcells 
> (uCell). Each 
> > is in
> > some state of charge/discharge.
> >
> > So imagine this:
> >
> > +--+--+--+--+--+--+.+--+---Plus terminal
> > S..S..S.[B].S..S..S.S..S
> > +--+--+--+--+--+--+.+--+---Minus terminal
> >
> > In this case, all of the "S"s represent a microcell (uCell) that is 
> > highly
> > sulfated, and the "[B]" represents a microcell that is in perfect 
> > condition,
> > and is taking a charge normally.
> >
> > If you try to put current into this lead acid cell, the sulfated 
> > uCells will
> > appear as open circuits (due to the sulfate's insulating 
> properties), 
> > and the
> > good uCell will take all of the current, and will keep the voltage 
> > down to a
> > low enough value that the sulfated uCells will not see any 
> significant
> > electrolysis action.
> >
> > So you say, "Pooh, I want the sulfated uCells to charge 
> too!" and up the
> > voltage across the lead acid cell, and poof!  The good 
> uCell dies from 
> > over
> > heating, revealing a new uCell that wants to charge, and 
> poof, it dies,
> > revealing another uCell that wants to take a charge, and poof...
> >
> > You get into a situation where your success causes your failure.
> >
> > If, instead, you apply high voltage pulses to the lead acid 
> cell, you can
> > sometimes beat the system.  The good uCells will take a 
> hit, but it is 
> > short
> > enough that they don't have time to burn up, and the 
> sulfated uCells will
> > get to draw enough current during the pulse that a little 
> electrolysis 
> > will
> > happen, and convert some of their sulfate back into oxide 
> and acid...
> >
> > Sometimes you can win by using a pulse charge system.
> >
> > However, there is a little physical problem that has to be 
> > understood.  Part
> > of the way the lead acid batteries get their high current handling 
> > densities
> > is because the lead plates are made to have high surface area. They 
> > are kind
> > of like sponges on the surface.  And, lead sulfate takes up 
> > significantly more
> > room than lead oxide.  Sorry, that is the way it just is.
> >
> > So, when a cell gets all sulfated up, the lead sulfate that 
> forms in 
> > the deep
> > nooks in the mossy lead electrodes fills the nook up so 
> full that it 
> > breaks
> > it apart, and damages the cell plate.  This happens, albeit slowly, 
> > even when
> > you treat the battery nicely.
> >
> > You can't win. Long term everything heads towards e

Re: [time-nuts] OT Gel Cell question

[Neville Michie]

Hi,

Lead acid cells have lead supports carrying lead oxide and lead metal active 
material 
in an electrolyte of sulphuric acid.
When they discharge, the sulphuric acid electrolyte is reacted with the oxides 
and metal
to form lead sulphate and the concentration of the acid falls, that is why 
garages 
used to check batteries with a hydrometer to measure the electrolyte 
concentration.
At the same time the terminal voltage drops and the internal resistance rises,
when the concentration of the electrolyte gets very low, the lead sulphate 
becomes 
soluble and will re-deposit all over the battery. With gel cells the 
electrolyte can 
be completely absorbed making the battery resistance infinitely high.
If you can get some current to flow, you may be lucky enough to get the battery 
to 
reform some electrolyte, conduct some more, and eventually charge. 
However, when flat the lead sulphate dissolves and redeposits all over the 
battery,
and when recharged will convert back to lead and lead oxide, often most 
inconveniently
bridging the plates to a short circuit.
The lesson is to not let the battery ever get flat.

Lead acid batteries have some very good features.
The terminal voltage rises as the concentration of the acid increases. So a 
constant voltage will
charge a cell, and current stops flowing when the electrolyte reaches its 
proper concentration.
The catch is, when you have a battery of several cells, if one cell gets weak, 
the others will be overcharged
causing gassing and over concentration of the electrolyte.
There is a judicious voltage that causes an acceptably low rate of gassing 
(the oxygen hydrogen catalytically recombining) that will keep the charges of 
cells equalised.
But it only takes one total discharge event to cause enough leakage in one cell
to bring about failure.

Lead acid batteries are also environmentally excellent.
They consist of nothing but pure lead and sulphuric acid and water.
Sulphuric acid is not volatile so you can make batteries out of old batteries
forever, recycling the acid, lead and water.
If made on a large scale they are also very efficient (99.9% +) electrically.

cheers,
Neville Michie
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Re: [time-nuts] OT Gel Cell question

[Alex Pummer]

it is not a high performance battery but extremely robust, see there 
http://www.nickel-iron-battery.com/

it is no polluting, it could be shorted out overcharged
if you are lucky and find one old forklift with Edison Battery -- which 
was built some fifty years egoit will out last you too
you could charge in current mode, C/10, 2C nothing will happen just 
replace evaporated water in the elctrtrolyt which is KOH

73
Alex


On 7/27/2014 2:41 PM, Chuck Harris wrote:
I too have spent a lot of time charging batteries using different 
methods on
various chemistries.  Once upon a time, I build a number of suitcase 
battery
chargers for the US Army that allowed them to charge every portable 
secondary

battery type that they had in inventory... SLA, AgO, NiCD, NIMH,
LiIon...  I proved a concept, and someone else got to make all of the 
money

off of it when the ARMY shopped my prototypes around... but I digress.

When you try to charge a sulfated lead acid cell, you can think of the 
cell
as being a bunch of little parallel lead acid microcells (uCell). Each 
is in

some state of charge/discharge.

So imagine this:

+--+--+--+--+--+--+.+--+---Plus terminal
S..S..S.[B].S..S..S.S..S
+--+--+--+--+--+--+.+--+---Minus terminal

In this case, all of the "S"s represent a microcell (uCell) that is 
highly
sulfated, and the "[B]" represents a microcell that is in perfect 
condition,

and is taking a charge normally.

If you try to put current into this lead acid cell, the sulfated 
uCells will
appear as open circuits (due to the sulfate's insulating properties), 
and the
good uCell will take all of the current, and will keep the voltage 
down to a

low enough value that the sulfated uCells will not see any significant
electrolysis action.

So you say, "Pooh, I want the sulfated uCells to charge too!" and up the
voltage across the lead acid cell, and poof!  The good uCell dies from 
over

heating, revealing a new uCell that wants to charge, and poof, it dies,
revealing another uCell that wants to take a charge, and poof...

You get into a situation where your success causes your failure.

If, instead, you apply high voltage pulses to the lead acid cell, you can
sometimes beat the system.  The good uCells will take a hit, but it is 
short

enough that they don't have time to burn up, and the sulfated uCells will
get to draw enough current during the pulse that a little electrolysis 
will

happen, and convert some of their sulfate back into oxide and acid...

Sometimes you can win by using a pulse charge system.

However, there is a little physical problem that has to be 
understood.  Part
of the way the lead acid batteries get their high current handling 
densities
is because the lead plates are made to have high surface area. They 
are kind
of like sponges on the surface.  And, lead sulfate takes up 
significantly more

room than lead oxide.  Sorry, that is the way it just is.

So, when a cell gets all sulfated up, the lead sulfate that forms in 
the deep
nooks in the mossy lead electrodes fills the nook up so full that it 
breaks
it apart, and damages the cell plate.  This happens, albeit slowly, 
even when

you treat the battery nicely.

You can't win. Long term everything heads towards entropy.

-Chuck Harris


Brooke Clarke wrote:

Hi Robert:

I've spent a lot of time charging batteries using different methods 
and on various

chemistries.

When the charge is in the form of a pulse, ideally including a 
reverse polarity

pulse, the charge is more effective.
This is also a way to sometimes, but not always, will recover a 
battery that

otherwise will not take a charge from a DC source.

I think this works because it takes some time for chemical reactions 
to work and by
using a pulse you can force the reaction to a higher level that you 
can't do using DC
without causing problems such as boiling the electrolyte.  For more 
info see Burp

Charging:
http://www.prc68.com/I/BatChg.shtml#Burp

Have Fun,

Brooke Clarke

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Re: [time-nuts] OT Gel Cell question

[Chuck Harris]

I too have spent a lot of time charging batteries using different methods on
various chemistries.  Once upon a time, I build a number of suitcase battery
chargers for the US Army that allowed them to charge every portable secondary
battery type that they had in inventory... SLA, AgO, NiCD, NIMH,
LiIon...  I proved a concept, and someone else got to make all of the money
off of it when the ARMY shopped my prototypes around... but I digress.

When you try to charge a sulfated lead acid cell, you can think of the cell
as being a bunch of little parallel lead acid microcells (uCell).  Each is in
some state of charge/discharge.

So imagine this:

+--+--+--+--+--+--+.+--+---Plus terminal
S..S..S.[B].S..S..S.S..S
+--+--+--+--+--+--+.+--+---Minus terminal

In this case, all of the "S"s represent a microcell (uCell) that is highly
sulfated, and the "[B]" represents a microcell that is in perfect condition,
and is taking a charge normally.

If you try to put current into this lead acid cell, the sulfated uCells will
appear as open circuits (due to the sulfate's insulating properties), and the
good uCell will take all of the current, and will keep the voltage down to a
low enough value that the sulfated uCells will not see any significant
electrolysis action.

So you say, "Pooh, I want the sulfated uCells to charge too!" and up the
voltage across the lead acid cell, and poof!  The good uCell dies from over
heating, revealing a new uCell that wants to charge, and poof, it dies,
revealing another uCell that wants to take a charge, and poof...

You get into a situation where your success causes your failure.

If, instead, you apply high voltage pulses to the lead acid cell, you can
sometimes beat the system.  The good uCells will take a hit, but it is short
enough that they don't have time to burn up, and the sulfated uCells will
get to draw enough current during the pulse that a little electrolysis will
happen, and convert some of their sulfate back into oxide and acid...

Sometimes you can win by using a pulse charge system.

However, there is a little physical problem that has to be understood.  Part
of the way the lead acid batteries get their high current handling densities
is because the lead plates are made to have high surface area.  They are kind
of like sponges on the surface.  And, lead sulfate takes up significantly more
room than lead oxide.  Sorry, that is the way it just is.

So, when a cell gets all sulfated up, the lead sulfate that forms in the deep
nooks in the mossy lead electrodes fills the nook up so full that it breaks
it apart, and damages the cell plate.  This happens, albeit slowly, even when
you treat the battery nicely.

You can't win. Long term everything heads towards entropy.

-Chuck Harris


Brooke Clarke wrote:

Hi Robert:

I've spent a lot of time charging batteries using different methods and on 
various
chemistries.

When the charge is in the form of a pulse, ideally including a reverse polarity
pulse, the charge is more effective.
This is also a way to sometimes, but not always, will recover a battery that
otherwise will not take a charge from a DC source.

I think this works because it takes some time for chemical reactions to work 
and by
using a pulse you can force the reaction to a higher level that you can't do 
using DC
without causing problems such as boiling the electrolyte.  For more info see 
Burp
Charging:
http://www.prc68.com/I/BatChg.shtml#Burp

Have Fun,

Brooke Clarke

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Re: [time-nuts] OT Gel Cell question

[Dale H. Cook]

At 04:09 PM 7/27/2014, Tom Miller wrote:

>If the battery is more than five years old it is most likely time to trade it 
>in for a new one.

I have used uninterruptable power supplies and standby power supplies for 
decades at work to keep mission-critical hardware online. I concur fully with 
Tom - depending upon the equipment they are used in and the quality of the 
original cells I replace gel cells every three to five years. It is much better 
to replace cells at a time of my choosing than to try to stretch their use and 
have them fail when needed.

Dale H. Cook, Contract Engineer, Roanoke/Lynchburg, VA
http://plymouthcolony.net/starcityeng/index.html 

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Re: [time-nuts] OT Gel Cell question

[Charles Steinmetz]

Robert wrote:

Anyone know why Gel Cell batteries go HI-Z if discharged below a 
certain level?

Also is there a way to rejuvenate a "dead" one?


As others have explained, the problem is sulfation.  I have had good 
results de-sulfating lead-acid batteries of all types (flooded, gel, 
AGM) with "BatteryMINDer" brand chargers/desulfators.  With badly 
sulfated batteries, rejuvination can take a long time.  Often, they 
return to a good approximation of "like new" performance.  Sometimes 
they improve but don't return to "like new."




Best regards,

Charles



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Re: [time-nuts] OT Gel Cell question

[Tom Miller]

There are some other failure modes for gel cell (and other lead acid types) 
batteries.


One is a shorted cell caused be the plates warping and breaching the 
separator insulation. This is not recoverable.


Another more likely failure is corrosion of the connections to the plates. 
Also not recoverable.


If the battery is more than five years old it is most likely time to trade 
it in for a new one.



Regards,
Tom



- Original Message - 
From: "Charles Steinmetz" 
To: "Discussion of precise time and frequency measurement" 


Sent: Sunday, July 27, 2014 3:41 PM
Subject: Re: [time-nuts] OT Gel Cell question



Robert wrote:

Anyone know why Gel Cell batteries go HI-Z if discharged below a certain 
level?

Also is there a way to rejuvenate a "dead" one?


As others have explained, the problem is sulfation.  I have had good 
results de-sulfating lead-acid batteries of all types (flooded, gel, AGM) 
with "BatteryMINDer" brand chargers/desulfators.  With badly sulfated 
batteries, rejuvination can take a long time.  Often, they return to a 
good approximation of "like new" performance.  Sometimes they improve but 
don't return to "like new."


<http://www.batteryminders.com/batteryminder-model-1500-12volt-1-5-amp-maintenance-charger-desulfator/>

Best regards,

Charles



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Re: [time-nuts] OT Gel Cell question

[Brooke Clarke]

Hi Robert:

I've spent a lot of time charging batteries using different methods and on 
various chemistries.

When the charge is in the form of a pulse, ideally including a reverse polarity 
pulse, the charge is more effective.
This is also a way to sometimes, but not always, will recover a battery that otherwise will not take a charge from a DC 
source.


I think this works because it takes some time for chemical reactions to work and by using a pulse you can force the 
reaction to a higher level that you can't do using DC without causing problems such as boiling the electrolyte.  For 
more info see Burp Charging:

http://www.prc68.com/I/BatChg.shtml#Burp

Have Fun,

Brooke Clarke
http://www.PRC68.com
http://www.end2partygovernment.com/2012Issues.html
http://www.prc68.com/I/DietNutrition.html

Robert Roehrig wrote:

Anyone know why Gel Cell batteries go HI-Z if discharged below a certain level?
Also is there a way to rejuvenate a "dead" one?
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Re: [time-nuts] OT Gel Cell question

[Chuck Harris]

Basically, it is a matter of thickness, and the quality of an insulator.

All lead acid cells work essentially the same:  A lead oxide electrode
immersed in sulfuric acid converts to lead sulfate when power is drawn from
the cell.  Lead sulfate is a very good insulator when it gets thick enough.

So, as the cell discharges, a lead oxide layer builds on the plates.  When
the lead sulfate gets thick enough, it insulates the remaining lead oxide
from the current flow, and the cell is discharged.

When it comes time to recharge the cell, you apply voltage, and if the
sulfate layer is still thin enough, current will be drawn, and electrolysis
action will commence, and the lead sulfate will be turned back into lead
oxide, and sulfuric acid.

If you let the dead cell sit around before recharging it, the lead sulfate
will have a chance to convert even more of the lead oxide to sulfate, and
the layer will grow thicker, and thicker, and become a better and better
electrical insulator To the point where the lead plates are completely
isolated and no current can pass The cell is ruined.

One way you can sometimes resurrect a cell in this ruined condition is
to apply a high voltage, with a low current limit to the cell.  This will
get some current flowing, and will convert, albeit slowly, some sulfate
back to lead oxide and sulfuric acid.

Such repairs take weeks, or months, to work, and have a great risk of
forming current hot spots which will physically destroy the plates.

Others say that applying a stream of short, high voltage pulses, to the
cell will break down the sulfate's insulation ability, and let the
electrolysis action commence.

Either method will work, somewhat.  And only on a cell that isn't too
far gone in the first place... eg. a cell that has only been dead for
a week or two.

-Chuck Harris

Robert Roehrig wrote:

Anyone know why Gel Cell batteries go HI-Z if discharged below a certain level?
Also is there a way to rejuvenate a "dead" one?
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Re: [time-nuts] OT Gel Cell question

[Chris Albertson]

I think the PbSO4 forms crystals rather then spongy deposits that can
re-disolve on the lead plates and reduces the effective surface are of
the plate.  Lower effective area means higher internal resistance.

With any lead acid battery the number of charge/dischage cycles
depends on how far you discharge them.  You can optimize your system
for either low size weight and cost or for "greatest number of amp
hours removed from the battery over it's lifetime"  The two goals are
in conflict.

Almost all the methods people use to "fix" a LA battery that no longer
holds a charge don't work so well.  If the battery did not have a long
enough service lit it's best to buy a replacement that is rated with
more amp hours.  Don't buy a gel cell unless yu really do need to use
it's ability to operate in all orientations, upside down and such.  If
it will stay upright a sealed, flooded battery will give better
performance.


>
>
> Anyone know why Gel Cell batteries go HI-Z if discharged below a certain
> level?
> Also is there a way to rejuvenate a "dead" one?



-- 

Chris Albertson
Redondo Beach, California
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Re: [time-nuts] OT Gel Cell question

[Mike Feher]

There are some YouTube videos showing how to rejuvenate. Also you can google
it for an explanation. I have wanted to try and rejuvenate some, even bought
the necessary ingredients, but never got around to it. Regards - Mike 

Mike B. Feher, EOZ Inc.
89 Arnold Blvd.
Howell, NJ, 07731
732-886-5960 office
908-902-3831 cell


-Original Message-
From: time-nuts-boun...@febo.com [mailto:time-nuts-boun...@febo.com] On
Behalf Of Robert Roehrig
Sent: Sunday, July 27, 2014 12:52 PM
To: time-nuts@febo.com
Subject: [time-nuts] OT Gel Cell question

Anyone know why Gel Cell batteries go HI-Z if discharged below a certain
level?
Also is there a way to rejuvenate a "dead" one?
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[time-nuts] OT Gel Cell question

[Robert Roehrig]

Anyone know why Gel Cell batteries go HI-Z if discharged below a certain level?
Also is there a way to rejuvenate a "dead" one?
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