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 > Effect of no absorption on LiFePo4?

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pianotuna

Regina, SK, Canada

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Posted: 01/22/23 12:06pm Link  |  Quote  |  Print  |  Notify Moderator

Time2roll,

I have seen articles that suggest every 30 cycles or days that the bank be balanced.

[image]

https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/

* This post was edited 01/22/23 12:15pm by pianotuna *


Regards, Don
My ride is a 28 foot Class C, 256 watts solar, 556 amp-hours of Telcom jars, 3000 watt Magnum hybrid inverter, Sola Basic Autoformer, Microair Easy Start.

3 tons

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Posted: 01/22/23 12:30pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Time2roll,

I have seen articles that suggest every 30 cycles or days that the bank be balanced.


“I have seen articles”??

Don, this has been addressed here by ‘actual users’ (meaning, not by you) on post that I know you’ve even past authored…I hate to resort to this, but perhaps (once and for all) maybe consider avoiding the impulse at offering near endless LFP controversy or disinformation - as you’re well aware, this particular has already been clarified…

Very Respectfully,

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time2roll

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Posted: 01/22/23 01:16pm Link  |  Quote  |  Print  |  Notify Moderator

pianotuna wrote:

Time2roll,

I have seen articles that suggest every 30 cycles or days that the bank be balanced.

[image]

https://www.solacity.com/how-to-keep-lifepo4-lithium-ion-batteries-happy/


I scanned it. Not sure what you are reading that would indicate the 30 day cycle.

And the article is flat wrong about the battery will only be at 90% charged at 14.4 volts and zero absorption time.


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bdosborn

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Posted: 01/22/23 05:41pm Link  |  Quote  |  Print  |  Notify Moderator

Some LiFePo4 batteries recommend an absorption stage, it gives the BMS cell balancer time to work. The voltage region that most BMS balancers work in is so high on the charge curve that actual balancing might only last a minute or two. Here's what Battleborn recommends:
https://battlebornbatteries.com/programm........-a-victron-smartsolar-charge-controller/
Bruce

* This post was edited 01/22/23 05:54pm by bdosborn *


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bdosborn

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Posted: 01/22/23 05:54pm Link  |  Quote  |  Print  |  Notify Moderator

Ramblin' Ralph wrote:


So what is the effect on the battery to not have absorption?


Probably nothing, your cells might be a little out of balance but that would be about it. Here's a link to a guy that explains what LFP charge settings should be:

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Bruce

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Posted: 01/22/23 06:28pm Link  |  Quote  |  Print  |  Notify Moderator

bdosborn wrote:

Some LiFePo4 batteries recommend an absorption stage, it gives the BMS cell balancer time to work. The voltage region that most BMS balancers work in is so high on the charge curve that actual balancing might only last a minute or two. Here's what Battleborn recommends:
https://battlebornbatteries.com/programm........-a-victron-smartsolar-charge-controller/
Bruce


Be advised, we are not talking rocket science here (except to those few FWC die-hards who snub a different approach).

Note that many charge controllers (as is Victron’s) are user configurable for a LiFePo4 battery format, and this configurability feature is why the moniker of ‘Absorption’ is used…Whether one cares to call it absorption or bulk (no matter…), a voltage somewhere in the high 13 teen’s to the mid 14 teen’s, not to exceed 14.6v (constant voltage, constant current) is all that’s really needed (higher voltage = faster charge)… And, cell balancing need only be done periodically…How so?? From my own observed experience, the need for rebalancing is a function of say number of ‘less than FULL charge/discharge’ cycles, and % of ‘depth of discharges’…From my perspective, and in the added interest of longevity, this is a far more cogent approach than some thoughtless ‘one size fits all’ (made-up…) calendar-scheduled approach…

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Posted: 01/22/23 07:24pm Link  |  Quote  |  Print  |  Notify Moderator

It seems like you're confusing my post with Don's, I didn't say anything about a "calendar-scheduled approach…".

The Battery Management System (BMS) in all LiFePO4 batteries has a cell balancer built into it and it works every time the battery is charged completely. Some batteries (like Battleborn) need an absorption stage to give the balancer more time to work; they typically only balance at 500mA so it can take awhile. Its transparent to most battery owners unless they have a BMS that displays battery cell voltages.

Its all in the specs of the battery you buy, if it doesn't say anything about an absorption stage then you don't need one.

Bruce

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Posted: 01/22/23 07:46pm Link  |  Quote  |  Print  |  Notify Moderator

bdosborn wrote:

It seems like you're confusing my post with Don's, I didn't say anything about a "calendar-scheduled approach…".

The Battery Management System (BMS) in all LiFePO4 batteries has a cell balancer built into it and it works every time the battery is charged completely. Some batteries (like Battleborn) need an absorption stage to give the balancer more time to work; they typically only balance at 500mA so it can take awhile. Its transparent to most battery owners unless they have a BMS that displays battery cell voltages.

Its all in the specs of the battery you buy, if it doesn't say anything about an absorption stage then you….

Bruce


Not intended, I was merely speaking to the broader audience, primarily revisiting the so-called every 30 day approach which Don had mentioned (Don has once before stated “every 7 days” applies…(FWIW, I disagree)…Yep, the balancing phase (at 14.x volts, whatever phase one opts to call it…) is relatively transparent - this is why I always recommend a Smart-Shunt so one can observe the occurrence and completion of re-balancing…Depending on the several previous variables I’d mentioned, this can take from several minutes to say roughly 20 min or so, often depending on battery capacity…

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Posted: 01/22/23 07:59pm Link  |  Quote  |  Print  |  Notify Moderator

10-4, thanks for the clarification....
Bruce

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Posted: 01/23/23 10:39am Link  |  Quote  |  Print  |  Notify Moderator

Good lord… add this to Dedmiston’s list of things men will over analyze and pick to death!

You have LFP batteries. Make sure they are relatively or fully charged, make sure they’re disconnected or no draw and then don’t think about them until you need them again


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