How to maintain 90% SOC on EVE LiFePO4 280Ah batteries

hummmingbear

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Over the next few weeks I'll be setting up a new battery system for my off-grid home. I bought 64 EVE Lifepo cells (280Ah@3.2V). I'll be setting them up in 4 groups of 16S (16S4P?).

I feel a bit unclear on how to charge the batteries up to 90% SOC. I'm assuming that's determined by the Absorption voltage I charge them to, but I'm not clear. Additionally, is my Victron SmartShunt going to be confused by any of this?

For instance: fully charged is 3.65V per cell. If I set my absorption to 3.5V per cell, will that be just fine? I'm using this post as a reference for ideal voltages, but I'm open to other suggestions.

Sorry if my question is unclear, but it reflects my own lack of clarity. Would appreciate any insight from someone who has already handled this. Much appreciated, and any other tips welcomed.
 
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BentleyJ

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Andy at Off Grid Garage did quite a bit of testing on this very subject. Check it out on YT. In my experience once you get over 3.45V per cell on LiFePO4 cells they will charge to approx. 95% given enough absorption time. I don't think it is necessary to push them all the way up to 3.65V. Your pick of 3.5V per cell will work just fine.
 

hummmingbear

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Andy at Off Grid Garage did quite a bit of testing on this very subject. Check it out on YT. In my experience once you get over 3.45V per cell on LiFePO4 cells they will charge to approx. 95% given enough absorption time. I don't think it is necessary to push them all the way up to 3.65V. Your pick of 3.5V per cell will work just fine.
I love his videos....he has so many though. Do you have a link or know what the title might be?

I definitely won't charge them to 3.65 except for maybe my initial charge/top balance.

I think I'm still confused on how my SmartShunt will behave. It wants a setting for charged voltage and current...would that be 3.65 even if I never bring it to that voltage?
 

BentleyJ

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Not sure about the smart shunt specifically but many State of Charge (SoC) devices will reset to 100% at a certain user defined voltage or current set points. Kind of like a recalibration at every recharge cycle once the target is hit. During absorption charging, which is usually done at constant voltage, the current flowing into the battery goes down due to the voltage in the battery going up creating a kind of "back pressure". Hopefully the instruction manual will give more details regarding how to set the values.
For example, in the Schneider Conext 6848 absorption switches over to float when the current falls to 2% (or something like that) of the Ah rating of the battery. At this point the battery is considered charged.
 
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