Re: [EVDL] Lee Hart Zener Regulator for Calb cells

[Lee Hart via EV]

Paul Dove via EV wrote:

If you have... no BMS and you are monitoring the cells, that
should be all the data you need to decide if a BMS is necessary.


That's a good point. With new, well-matched cells, you might be just 
fine (at least for now). Since crappy BMS can create as many problems as 
they solve, you may be better off just monitoring them yourself (you 
become the BMS).


My simply little Batt-Bridge is one way to tell if something is going 
wrong without obsessively monitoring the cells all the time. It doesn't 
tell you which one is different, but it alerts you that it's time to get 
out the voltmeter and find out!


There are also some mighty simple voltmeter circuits that can be used 
with a small number of cells. Traditional analog meters can be found 
that draw very low current (well under 1ma) so they can be left 
connected all the time.


Or, you can use super-bright blue or white LEDs as voltmeters. They need 
at least 3v to light, and can be quite visible with less than 1ma. 
Choose a series resistor for (say) 1ma at 4v. Then the brightness will 
vary from 0 to max as the cell goes from 3v to 4v. Mount them all right 
next to each other in a panel. The human eye is extremely sensitive to 
brightness, so you can easily judge which one is the brightness (highest 
voltage) or dimmest (lowest voltage).


--
If we knew what we were doing, it wouldn't be called research, would it?
-- Albert Einstein
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] Lee Hart Zener Regulator for Calb cells

[Lee Hart via EV]

damon henry via EV wrote:

Hi, I am wondering if anyone has adapted Lee Hart's Zener regulators
for lithium cell use.


Cor has covered the issues very well.

I've tried them with lithiums; but they don't work well. True zener 
diodes (voltages less than about 6v) are pretty soft. There is about a 
2-3 volt-wide range over which they gradually change from non-conducting 
to fully conducting.


This soft "knee" makes them unsuitable for a zener-based lithium 
regulator. They still draw significant current even 1 volt below the 
voltage where you want them off.


"Zener" diodes above 6-7v are in fact Avalanche diodes. As the name 
implies, they conduct much less below their rated voltage, and a lot 
more above it, with a very sharp transition. The 6.2v and 6.8v diodes 
used in the 12v zener-lamp regulator are this type. They conduct far 
less current with an open-circuit battery (13v or less), but fully 
conduct when overcharging (15v or more).


There are zener-like replacements; essentially integrated circuits 
designed to behave more like an "ideal" zener diode. The 25-cent TL431 
is a common example. It looks like a transistor (3 leads instead of two) 
but acts like a 2.5v zener (adjustable with the 3rd lead). It "leaks" 
about 0.4ma below this (which is actually its supply current), and 
conducts up to 150ma above this. That's pretty good; about a 600:1 
change. There are lots of similar parts, with lower leakage but lower 
conduction.


PS: This zener-lamp regulator is more sophisticated than it look. 
Avalanche diodes (as used in the 6v, 8v, and 12v versions) have a 
positive temperature coefficient. That means if they overheat, their 
voltage rises, which tends to limit the power so they don't fail. True 
zeners (under 6v) have a *negative* temperature coefficient. If they 
overheat, they draw *more* current, and burn themselves up!


A lamp is used (instead of an LED) so it also acts as a fuse. Normal 
regulators use lots of semiconductors which can fail "on". This loads 
the cell continuously, runs it dead, and destroy it! But if a zener 
shorts here, the lamp sees too much voltage and burns out. Now you have 
an open circuit, and saved your cell. :-)


The lamp also makes it "idiot proof". If you hook it up backwards, or to 
the wrong place in the circuit, or there's a loose connection, or a cell 
fails open, the lamp simply fails open -- no fireworks or fires.

--
The greatest pleasure in life is to create something that wasn't
there before. -- Roy Spence
--
Lee Hart, 814 8th Ave N, Sartell MN 56377, www.sunrise-ev.com
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Re: [EVDL] Lee Hart Zener Regulator for Calb cells

[Paul Dove via EV]

If you have a bike with no BMS and you are monitoring the cells that should be 
all the data you need to decide if a BMS is necessary. Not what others tell you.

What are you observations of the cells

Sent from my iPad

> On Jun 23, 2015, at 6:29 PM, damon henry via EV  wrote:
> 
> 
> 
> 
> 
> 
> Thanks Cor, for the information.  I thought I would like to play with these, 
> but maybe not due to some of the concerns you bring up.
> I currently have 16 60ahr calb cells I am learning with on my motorcycle with 
> no BMS.  The investment in this small of pack  is not huge and hands on 
> learning is worthwhile, so I don't mind being my own BMS in this case.  I 
> would eventually like to put Calb cells in my truck.  I will likely install a 
> BMS in my truck as that will be a larger investment and more cells to try and 
> keep track of manually.  Right now I am leaning towards Orion.  So the Zener 
> balancers were just going to be for experimenting and observation.
> I understand the risks of not installing a BMS, but it is always interesting 
> comparing that against the risk of having something permanently wired across 
> your cells.
> damon
> 
>> Date: Tue, 23 Jun 2015 11:18:42 -0700
>> To: ev@lists.evdl.org
>> Subject: Re: [EVDL] Lee Hart Zener Regulator for Calb cells
>> From: ev@lists.evdl.org
>> 
>> Lee has discussed this in the past, it is likely in the archives.
>> I see three main issues:
>> - at lower voltage, the zener knee gets very soft so unless you use 
>> additional electronics to amplify, the zener itself does not work very well 
>> on a single cell as you already indicated, two cells might indeed be better 
>> since around 6V the zeners have the best characteristics but that introduces 
>> issues with imbalance between the two cells
>> - Voltage differences while charging are very small with most types of 
>> Lithium. 3.2V at rest but 3.5V is over-charging a LiFePO4 cell whereas a 
>> flooded/AGM lead-acid battery can easily go from 12V to 15V and it does not 
>> hurt them to be sitting at 15V while balancing for an hour.
>> - leakage and failure: while zeners are supposed to go "on" at a certain 
>> voltage, they will leak below that voltage so you are introducing extra 
>> "self-discharge" which can very per cell with the properties of the zener, 
>> so in a sense you are making the situation for Li-Ion worse. Also zeners can 
>> fail (shorted typically) and mechanically fail and the Lithium cells will 
>> not take well to being over-charged due to a failure
>> 
>> Cor van de Water
>> Chief Scientist
>> Proxim Wireless
>> 
>> office +1 408 383 7626Skype: cor_van_de_water
>> XoIP   +31 87 784 1130private: cvandewater.info
>> www.proxim.com
>> 
>> 
>> This email message (including any attachments) contains confidential and 
>> proprietary information of Proxim Wireless Corporation.  If you received 
>> this message in error, please delete it and notify the sender.  Any 
>> unauthorized use, disclosure, distribution, or copying of any part of this 
>> message is prohibited.
>> 
>> 
>> -Original Message-
>> From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of damon henry via EV
>> Sent: Tuesday, June 23, 2015 10:37 AM
>> To: EV List
>> Subject: [EVDL] Lee Hart Zener Regulator for Calb cells
>> 
>> Hi,
>> I am wondering if anyone has adapted Lee Hart's Zener regulators for lithium 
>> cell use.  I don't think the voltage of one cell is high enough to use this 
>> type of device on, but I think proper values can be found to regulate two 
>> cells in series.  I would love to experiment with some of these and would 
>> like full bypass at 6.8 volts.  I believe the 12 volt model can be tweaked 
>> by picking appropriate replacement Zener diodes, but I don't do a lot of 
>> this type of design, so I am not familiar with what is available or where to 
>> source the parts.  Any help would be appreciated.
>> thanks Damon
>> Here is a link to Lee's 
>> design.http://www.sunrise-ev.com/LeesEVs.htm#zenerlamp   
>>   
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Re: [EVDL] Lee Hart Zener Regulator for Calb cells

[damon henry via EV]

Thanks Cor, for the information.  I thought I would like to play with these, 
but maybe not due to some of the concerns you bring up.
I currently have 16 60ahr calb cells I am learning with on my motorcycle with 
no BMS.  The investment in this small of pack  is not huge and hands on 
learning is worthwhile, so I don't mind being my own BMS in this case.  I would 
eventually like to put Calb cells in my truck.  I will likely install a BMS in 
my truck as that will be a larger investment and more cells to try and keep 
track of manually.  Right now I am leaning towards Orion.  So the Zener 
balancers were just going to be for experimenting and observation.
I understand the risks of not installing a BMS, but it is always interesting 
comparing that against the risk of having something permanently wired across 
your cells.
damon

> Date: Tue, 23 Jun 2015 11:18:42 -0700
> To: ev@lists.evdl.org
> Subject: Re: [EVDL] Lee Hart Zener Regulator for Calb cells
> From: ev@lists.evdl.org
> 
> Lee has discussed this in the past, it is likely in the archives.
> I see three main issues:
> - at lower voltage, the zener knee gets very soft so unless you use 
> additional electronics to amplify, the zener itself does not work very well 
> on a single cell as you already indicated, two cells might indeed be better 
> since around 6V the zeners have the best characteristics but that introduces 
> issues with imbalance between the two cells
> - Voltage differences while charging are very small with most types of 
> Lithium. 3.2V at rest but 3.5V is over-charging a LiFePO4 cell whereas a 
> flooded/AGM lead-acid battery can easily go from 12V to 15V and it does not 
> hurt them to be sitting at 15V while balancing for an hour.
> - leakage and failure: while zeners are supposed to go "on" at a certain 
> voltage, they will leak below that voltage so you are introducing extra 
> "self-discharge" which can very per cell with the properties of the zener, so 
> in a sense you are making the situation for Li-Ion worse. Also zeners can 
> fail (shorted typically) and mechanically fail and the Lithium cells will not 
> take well to being over-charged due to a failure
> 
> Cor van de Water
> Chief Scientist
> Proxim Wireless
> 
> office +1 408 383 7626Skype: cor_van_de_water
> XoIP   +31 87 784 1130private: cvandewater.info
> www.proxim.com
> 
> 
> This email message (including any attachments) contains confidential and 
> proprietary information of Proxim Wireless Corporation.  If you received this 
> message in error, please delete it and notify the sender.  Any unauthorized 
> use, disclosure, distribution, or copying of any part of this message is 
> prohibited.
> 
> 
> -Original Message-
> From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of damon henry via EV
> Sent: Tuesday, June 23, 2015 10:37 AM
> To: EV List
> Subject: [EVDL] Lee Hart Zener Regulator for Calb cells
> 
> Hi,
> I am wondering if anyone has adapted Lee Hart's Zener regulators for lithium 
> cell use.  I don't think the voltage of one cell is high enough to use this 
> type of device on, but I think proper values can be found to regulate two 
> cells in series.  I would love to experiment with some of these and would 
> like full bypass at 6.8 volts.  I believe the 12 volt model can be tweaked by 
> picking appropriate replacement Zener diodes, but I don't do a lot of this 
> type of design, so I am not familiar with what is available or where to 
> source the parts.  Any help would be appreciated.
> thanks Damon
> Here is a link to Lee's 
> design.http://www.sunrise-ev.com/LeesEVs.htm#zenerlamp
>   
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Re: [EVDL] Lee Hart Zener Regulator for Calb cells

[Cor van de Water via EV]

Lee has discussed this in the past, it is likely in the archives.
I see three main issues:
- at lower voltage, the zener knee gets very soft so unless you use additional 
electronics to amplify, the zener itself does not work very well on a single 
cell as you already indicated, two cells might indeed be better since around 6V 
the zeners have the best characteristics but that introduces issues with 
imbalance between the two cells
- Voltage differences while charging are very small with most types of Lithium. 
3.2V at rest but 3.5V is over-charging a LiFePO4 cell whereas a flooded/AGM 
lead-acid battery can easily go from 12V to 15V and it does not hurt them to be 
sitting at 15V while balancing for an hour.
- leakage and failure: while zeners are supposed to go "on" at a certain 
voltage, they will leak below that voltage so you are introducing extra 
"self-discharge" which can very per cell with the properties of the zener, so 
in a sense you are making the situation for Li-Ion worse. Also zeners can fail 
(shorted typically) and mechanically fail and the Lithium cells will not take 
well to being over-charged due to a failure

Cor van de Water
Chief Scientist
Proxim Wireless

office +1 408 383 7626  Skype: cor_van_de_water
XoIP   +31 87 784 1130  private: cvandewater.info
www.proxim.com


This email message (including any attachments) contains confidential and 
proprietary information of Proxim Wireless Corporation.  If you received this 
message in error, please delete it and notify the sender.  Any unauthorized 
use, disclosure, distribution, or copying of any part of this message is 
prohibited.


-Original Message-
From: EV [mailto:ev-boun...@lists.evdl.org] On Behalf Of damon henry via EV
Sent: Tuesday, June 23, 2015 10:37 AM
To: EV List
Subject: [EVDL] Lee Hart Zener Regulator for Calb cells

Hi,
I am wondering if anyone has adapted Lee Hart's Zener regulators for lithium 
cell use.  I don't think the voltage of one cell is high enough to use this 
type of device on, but I think proper values can be found to regulate two cells 
in series.  I would love to experiment with some of these and would like full 
bypass at 6.8 volts.  I believe the 12 volt model can be tweaked by picking 
appropriate replacement Zener diodes, but I don't do a lot of this type of 
design, so I am not familiar with what is available or where to source the 
parts.  Any help would be appreciated.
thanks Damon
Here is a link to Lee's design.http://www.sunrise-ev.com/LeesEVs.htm#zenerlamp  
  
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[EVDL] Lee Hart Zener Regulator for Calb cells

[damon henry via EV]

Hi,
I am wondering if anyone has adapted Lee Hart's Zener regulators for lithium 
cell use.  I don't think the voltage of one cell is high enough to use this 
type of device on, but I think proper values can be found to regulate two cells 
in series.  I would love to experiment with some of these and would like full 
bypass at 6.8 volts.  I believe the 12 volt model can be tweaked by picking 
appropriate replacement Zener diodes, but I don't do a lot of this type of 
design, so I am not familiar with what is available or where to source the 
parts.  Any help would be appreciated.
thanks Damon
Here is a link to Lee's design.http://www.sunrise-ev.com/LeesEVs.htm#zenerlamp  
  
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