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Charge voltage

Norm01

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Feb 9, 2021
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Hi all, finishing up my 4S battery pack for my RV. It’s made up of CATL 302A grade A cells and a Daly 250A smart BMS. Data sheet on these says maximum charge voltage is 3.65v, I was going to limit to 3.6v however I see on many YouTube videos people limiting to 3.5v. What is the general consensus to prolong battery life and get nearly 100% SOC.
 
My top balancing was done at 3.6v In parallel. I went to series and applied a load and am down to +/- 3.3 now. So if I read you correctly you would,set the BMS charge voltage to 3.5V and 14v total for daily operation. Thanks.
 
My top balancing was done at 3.6v In parallel. I went to series and applied a load and am down to +/- 3.3 now. So if I read you correctly you would,set the BMS charge voltage to 3.5V and 14v total for daily operation. Thanks.
It's normal the batteries drop down, let them sit a couple days' in parallel, then series.
 
I think your missing my question, should I set my BMS to charge to 3.5 or 3.6 now that they’re is series and BMS hooked up.
 
should I set my BMS to charge to 3.5 or 3.6
You don't set your BMS to control charging. The BMS is set to the safety limits of the cells/battery (2.5V to 3.65V or narrower by a bit).

You set the charge controller to control the charging (get it? its a charge controller).
Here is a voltage vs SOC chart so you can see where you want to charge. Hint: 3.65V is the theoretical limit of the cells before they are destroyed, its NOT really where they are meant to be charged everyday.

LiFePO4 SoC chart.png
 
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