[RE-wrenches] Lithium battery charge rate

[Starlight]

Hi Jay,

For our LFMP and LFP batteries, it has never mattered. 
 
As long as current is flowing, the SoC is increasing and the voltage will rise until it reaches the CV set point.   

Typically cell balance occurs when a cell voltage reaches a set point where a load turns on across that cell. Typically about 3.55 V. When we see out of balance battery packs, we typically find that the bank has been habitually deficit charged. Someone has spread an idea that you should not fully charge your Li battery. (Thanks YouTube gurus) This leads to unbalanced cells over time. Each cell has a slightly different charge efficiency and the SoC will slowly drift. This affects all cells. Unbalanced cells lead to an apparent loss of capacity.

We have LFMP banks sitting as back up power for 10 years now with a constant 3.6Vpc. No problems with just very low current maintaining the bank. 

Larry Crutcher
Starlight Solar Power Systems


On Jun 26, 2023, at 1:57 PM, Jay via RE-wrenches <re-wrenches at lists.re-wrenches.org> wrote:

Hi All

I’m wondering if minimum charge amps for lithium is common or not?

Or does it have to do with the cell shape: cylindrical vs prismatic vs pouch?

A client purchased some EG4 batteries and they are getting a bit out of balanced. Tech support didn’t suggest higher volts or longer absorb but did mention they need 30-50 amps charge. It’s not in the manual. 

Wondering what you all think and know

Thx
Jay
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