Re: [RE-wrenches] Outback MX-60 - Li-ion charging

[larrycrutcher]

Steve reminded me of something, probably because it is not very common. If you 
are recharging at 1C or greater rates, the Absorb cycle will need to be longer 
if you want to return all energy to the battery. Example: For a 300AH battery, 
1C would be 300 Amps or over 16kW for a 48V bank. 

Since it’s not economical to build a PV system that can fully charge from 100% 
DoD in just 1 hour of full sun, it’s not too likely you will use 1C charge 
rates. If you are generator charging, this may be true, in fact I recommend 
charging at 1C (or max the brand will allow) to reduce generator run time.

Larry Crutcher




On Dec 1, 2021, at 2:09 PM, Steve Higgins  wrote:

I have found this to be true as well, especially when multiple LFP battery 
blocks are in parallel . I like to see the charge rate around the C2 to C8 
Rate... the lower the charge rate the longer the absorb.On the LFP's we 
advise around 20-60 mins absorb time again depending on the amount of current 
availability, and quantity of parallel connections.   

With the MX60 you can adjust the float voltage to the 3.65vpc, and set the 
timer for the rest of the solar day to ensure the batteries are getting 
balanced...  


   
  
  
  
  
  
  
 Steve Higgins ⋅ 
Technical Services Manager
t +1.902.597.4020  m +1.206.790.5840
f +1.902.597.8447  e st...@surrette.com 
  
   
<>   <> 
  <> 
 <> 
  


 
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On Wed, Dec 1, 2021 at 12:24 PM b...@midnitesolar.com 
 mailto:b...@midnitesolar.com>> wrote:

Thanks Larry.

The information to stop when absorb voltage was reached is like, 10 or more 
years old and so I
don't know if that voltage reach and stop charging algorithm is still used by 
any BMS's.

This is probably why we had to add a logic input to tell the controller to stop 
charging from the BMS.

After the 0.3 hours at Absorb for balancing (which makes perfect sense for a 
BMS),  does the MX/FM then
go to float at 3.65V per cell after that ?

Does your systems just restart a new bulk/absorb cycle the next morning or do 
you also do a Re-Bulk if
or when battery voltage falls below a certain point ?

Also, listening (reading) chat here on what might be needed that may not have 
been addressed by
Li battery, BMS and/or charge controller manufacturers.


Thanks,
boB





On 12/1/2021 12:03 PM, larrycrutcher wrote:
> If you stop charging a Li-ion battery when the CV (absorb voltage) is 
> reached, you may reduce or stop the needed cell balancing time. We have had 
> customers develop unbalanced series cells from continuous undercharging. 
> Because of internal cell resistance, one cell will always reach saturation 
> before others in the group. This can happen at less than 1mv difference. The 
> more unbalanced a group of series cells are, the sooner one cells voltage 
> will spike causing over voltage events at a lower terminal voltage.   
> 
> Our Li batteries (Elite Power Solutions-GBS and LiFeBlue) can be held at 
> 3.65Vpc continuously, no problems. We have customers using both MX and FM 
> controllers for 8 years now. Our recommended setting for the Absorb timer is 
> 0.3 hours. This allows for cell balancing and for the capacity meter 
> to recalibrate. Some chargers will stay at CV for several hours. No problems 
> doing this either as long as cell voltage is lower than 3.8V (LFP chem.).
> 
> Larry Crutcher
> Starlight Solar Power Systems
> 
> 
> 
> On Dec 1, 2021, at 9:38 AM, b...@midnitesolar.com 
>  wrote:
> 
> 
> 
> Depends on the requirement for the BMS.
> 
> Usually, but not 100% always, the requirement is to get the voltage up to 
> 

Re: [RE-wrenches] Outback MX-60 - Li-ion charging

[larrycrutcher]

boB,

Yes, the Absorb timer in the FM and MX determine maximum CV time. From FM 
manual:
 While the batteries are held at this voltage, the ChgT counter in the Misc 
menu counts up from zero toward the user-defined Absorb Time Limit. (See pages 
44 and 49.) The charger will exit this stage and enter the Float stage if the 
ChgT timer reaches the time limit, or if the Absorb End Amps setting is 
reached. 

Float V is what ever you programed in Charger Setup. We normally Float at 3.4 
to 3.45Vpc, 13.6V to 13.8V for 12V bank. I find that Rebulk is not very 
important. Float mode can easily replace energy to the battery at the same rate 
as Bulk/Absorb would without the higher voltage and additional absorb time. It 
does not take much voltage delta to produce high current. 

Each sunrise restarts the controller. This is good to produce another Absorb 
cycle for cell balancing.


Larry Crutcher
Starlight Solar Power Systems




On Dec 1, 2021, at 1:24 PM, b...@midnitesolar.com wrote:


Thanks Larry.

The information to stop when absorb voltage was reached is like, 10 or more 
years old and so I
don't know if that voltage reach and stop charging algorithm is still used by 
any BMS's.

This is probably why we had to add a logic input to tell the controller to stop 
charging from the BMS.

After the 0.3 hours at Absorb for balancing (which makes perfect sense for a 
BMS),  does the MX/FM then
go to float at 3.65V per cell after that ?

Does your systems just restart a new bulk/absorb cycle the next morning or do 
you also do a Re-Bulk if
or when battery voltage falls below a certain point ?

Also, listening (reading) chat here on what might be needed that may not have 
been addressed by
Li battery, BMS and/or charge controller manufacturers.


Thanks,
boB





On 12/1/2021 12:03 PM, larrycrutcher wrote:
> If you stop charging a Li-ion battery when the CV (absorb voltage) is 
> reached, you may reduce or stop the needed cell balancing time. We have had 
> customers develop unbalanced series cells from continuous undercharging. 
> Because of internal cell resistance, one cell will always reach saturation 
> before others in the group. This can happen at less than 1mv difference. The 
> more unbalanced a group of series cells are, the sooner one cells voltage 
> will spike causing over voltage events at a lower terminal voltage.   
> 
> Our Li batteries (Elite Power Solutions-GBS and LiFeBlue) can be held at 
> 3.65Vpc continuously, no problems. We have customers using both MX and FM 
> controllers for 8 years now. Our recommended setting for the Absorb timer is 
> 0.3 hours. This allows for cell balancing and for the capacity meter to 
> recalibrate. Some chargers will stay at CV for several hours. No problems 
> doing this either as long as cell voltage is lower than 3.8V (LFP chem.).
> 
> Larry Crutcher
> Starlight Solar Power Systems
> 
> 
> 
> On Dec 1, 2021, at 9:38 AM, b...@midnitesolar.com 
>  wrote:
> 
> 
> 
> Depends on the requirement for the BMS.
> 
> Usually, but not 100% always, the requirement is to get the voltage up to 
> "absorb" and then stop charging.
> 
> Just set the min and max  times very low, like 1 minute and that should 
> satisfy that one.
> 
> I do not remember if the MX60 had a Re-Bulk  setting but I think it did ?
> 
> The MX did not have a logic input for turning it on and off of course.  OB 
> had a communications
> device that converted their communications protocol to Modbus or Ethernet I 
> think it was which
> may (or may not) be able to make it work.
> 
> Could always buy something newer and keep the MX60 as a spare.  
> 
> boB
> 
> 
> 
> On 12/1/2021 9:10 AM, frenergy wrote:
>> boB,
>> 
>> Interesting...Sounds like this is not a candidate for L-ion 
>> batteries.
>> 
>> Bill
>> 
>> On 11/30/2021 10:47 PM, b...@midnitesolar.com  
>> wrote:
>>> 
>>> Hi Bill
>>> 
>>> As I remember, the min is of course... Minimum time in Absorb.
>>> 
>>> Max is maximum time in absorb but depended on how long it took to get from 
>>> Bulk MPPT to that Absorb voltage.
>>> 
>>> So if it took 3 hours to get to Absorb that morning and you had t set for 
>>> Max 2 hours,  it would Absorb for 2 hours.
>>> 
>>> If it only took 1 and 1/2 hours to reach Absorb voltage, the MX60 would 
>>> Absorb for 1 and 1/2 hours.
>>> 
>>> It worked "OK"  but these days I would probably just set it for min of some 
>>> 2 or 3 hours and then a max could be the same
>>> time or longer for FLA batteries.
>>> 
>>> boB
>>> 
>>> 
>>> 
>>> On 11/30/2021 7:16 PM, frenergy wrote:
 Yes, the old one, not the FM.  This oldie had an interesting way to set 
 the absorption time. You would set the "min" time (in minutes) and you 
 would set the "max" time (in hours, you have to set it to 1,2,3 or 4 
 hours).
 
 I need to know if I set the "min" to 10 minutes and the "max" 
 time to one hour or two or three or four, how 

Re: [RE-wrenches] Outback MX-60 - Li-ion charging

[b...@midnitesolar.com]

Thanks Larry.

The information to stop when absorb voltage was reached is like, 10 or 
more years old and so I
don't know if that voltage reach and stop charging algorithm is still 
used by any BMS's.


This is probably why we had to add a logic input to tell the controller 
to stop charging from the BMS.


After the 0.3 hours at Absorb for balancing (which makes perfect sense 
for a BMS),  does the MX/FM then

go to float at 3.65V per cell after that ?

Does your systems just restart a new bulk/absorb cycle the next morning 
or do you also do a Re-Bulk if

or when battery voltage falls below a certain point ?

Also, listening (reading) chat here on what might be needed that may not 
have been addressed by

Li battery, BMS and/or charge controller manufacturers.


Thanks,
boB





On 12/1/2021 12:03 PM, larrycrutcher wrote:
If you stop charging a Li-ion battery when the CV (absorb voltage) is 
reached, you may reduce or stop the needed cell balancing time. We 
have had customers develop unbalanced series cells from continuous 
undercharging. Because of internal cell resistance, one cell will 
always reach saturation before others in the group. This can happen at 
less than 1mv difference. The more unbalanced a group of series cells 
are, the sooner one cells voltage will spike causing over voltage 
events at a lower terminal voltage.


Our Li batteries (Elite Power Solutions-GBS and LiFeBlue) can be held 
at 3.65Vpc continuously, no problems. We have customers using both MX 
and FM controllers for 8 years now. Our recommended setting for the 
Absorb timer is 0.3 hours. This allows for cell balancing and for the 
capacity meter to recalibrate. Some chargers will stay at CV for 
several hours. No problems doing this either as long as cell voltage 
is lower than 3.8V (LFP chem.).


Larry Crutcher
Starlight Solar Power Systems



On Dec 1, 2021, at 9:38 AM, b...@midnitesolar.com wrote:



Depends on the requirement for the BMS.

Usually, but not 100% always, the requirement is to get the voltage up 
to "absorb" and then stop charging.


Just set the min and max  times very low, like 1 minute and that 
should satisfy that one.


I do not remember if the MX60 had a Re-Bulk  setting but I think it did ?

The MX did not have a logic input for turning it on and off of 
course.  OB had a communications
device that converted their communications protocol to Modbus or 
Ethernet I think it was which

may (or may not) be able to make it work.

Could always buy something newer and keep the MX60 as a spare.

boB



On 12/1/2021 9:10 AM, frenergy wrote:


boB,

            Interesting...Sounds like this is not a candidate for 
L-ion batteries.


Bill

On 11/30/2021 10:47 PM, b...@midnitesolar.com wrote:


Hi Bill

As I remember, the min is of course... Minimum time in Absorb.

Max is maximum time in absorb but depended on how long it took to 
get from Bulk MPPT to that Absorb voltage.


So if it took 3 hours to get to Absorb that morning and you had t 
set for Max 2 hours,  it would Absorb for 2 hours.


If it only took 1 and 1/2 hours to reach Absorb voltage, the MX60 
would Absorb for 1 and 1/2 hours.


It worked "OK"  but these days I would probably just set it for min 
of some 2 or 3 hours and then a max could be the same

time or longer for FLA batteries.

boB



On 11/30/2021 7:16 PM, frenergy wrote:


Yes, the old one, not the FM.  This oldie had an interesting way to 
set the absorption time. You would set the "min" time (in minutes) 
and you would set the "max" time (in hours, you have to set it to 
1,2,3 or 4 hours).


            I need to know if I set the "min" to 10 minutes and the 
"max" time to one hour or two or three or four, how long will it 
stay in absorb?


            I called Outback and Megan there didn't know how this 
old fart works, apparently tech support isn't supporting us their 
old relics.


Bill

Feather River Solar Electric
Bill Battagin, Owner
4291 Nelson St.
Taylorsville, CA 95983
530.284.7849
CA Lic 874049
solar powered since 1982





 
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Re: [RE-wrenches] Outback MX-60 - Li-ion charging

[larrycrutcher]

If you stop charging a Li-ion battery when the CV (absorb voltage) is reached, 
you may reduce or stop the needed cell balancing time. We have had customers 
develop unbalanced series cells from continuous undercharging. Because of 
internal cell resistance, one cell will always reach saturation before others 
in the group. This can happen at less than 1mv difference. The more unbalanced 
a group of series cells are, the sooner one cells voltage will spike causing 
over voltage events at a lower terminal voltage.   

Our Li batteries (Elite Power Solutions-GBS and LiFeBlue) can be held at 
3.65Vpc continuously, no problems. We have customers using both MX and FM 
controllers for 8 years now. Our recommended setting for the Absorb timer is 
0.3 hours. This allows for cell balancing and for the capacity meter to 
recalibrate. Some chargers will stay at CV for several hours. No problems doing 
this either as long as cell voltage is lower than 3.8V (LFP chem.).

Larry Crutcher
Starlight Solar Power Systems



On Dec 1, 2021, at 9:38 AM, b...@midnitesolar.com wrote:



Depends on the requirement for the BMS.

Usually, but not 100% always, the requirement is to get the voltage up to 
"absorb" and then stop charging.

Just set the min and max  times very low, like 1 minute and that should satisfy 
that one.

I do not remember if the MX60 had a Re-Bulk  setting but I think it did ?

The MX did not have a logic input for turning it on and off of course.  OB had 
a communications
device that converted their communications protocol to Modbus or Ethernet I 
think it was which
may (or may not) be able to make it work.

Could always buy something newer and keep the MX60 as a spare.  

boB



On 12/1/2021 9:10 AM, frenergy wrote:
> boB,
> 
> Interesting...Sounds like this is not a candidate for L-ion 
> batteries.
> 
> Bill
> 
> On 11/30/2021 10:47 PM, b...@midnitesolar.com  
> wrote:
>> 
>> Hi Bill
>> 
>> As I remember, the min is of course... Minimum time in Absorb.
>> 
>> Max is maximum time in absorb but depended on how long it took to get from 
>> Bulk MPPT to that Absorb voltage.
>> 
>> So if it took 3 hours to get to Absorb that morning and you had t set for 
>> Max 2 hours,  it would Absorb for 2 hours.
>> 
>> If it only took 1 and 1/2 hours to reach Absorb voltage, the MX60 would 
>> Absorb for 1 and 1/2 hours.
>> 
>> It worked "OK"  but these days I would probably just set it for min of some 
>> 2 or 3 hours and then a max could be the same
>> time or longer for FLA batteries.
>> 
>> boB
>> 
>> 
>> 
>> On 11/30/2021 7:16 PM, frenergy wrote:
>>> Yes, the old one, not the FM.  This oldie had an interesting way to set the 
>>> absorption time. You would set the "min" time (in minutes) and you would 
>>> set the "max" time (in hours, you have to set it to 1,2,3 or 4 hours).
>>> 
>>> I need to know if I set the "min" to 10 minutes and the "max" 
>>> time to one hour or two or three or four, how long will it stay in absorb?
>>> 
>>> I called Outback and Megan there didn't know how this old fart 
>>> works, apparently tech support isn't supporting us their old relics.
>>> 
>>> Bill
>>> 
>>> Feather River Solar Electric
>>> Bill Battagin, Owner
>>> 4291 Nelson St.
>>> Taylorsville, CA 95983
>>> 530.284.7849
>>> CA Lic 874049
>>> solar powered since 1982
>>> 
>>> 
> 
> 
>  
> 
>   Virus-free. www.avast.com 
> 
>  
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