Charge voltage

[Norm01]

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.

 

[Joe BoyKey]

3.5 and let them sit for a couple days in Parallel, then series, add JBD Bms and good o go, Joe.

 

[Norm01]

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.

 

[Joe BoyKey]

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.

 

[Norm01]

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.

 

[time2roll]

3.45 to 3.50 is plenty. The curve is logarithmic not linear.

 

[MisterSandals]

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.

 

[Norm01]

I do get it and that information is exactly what I was looking for. Thanks.

 

[MisterSandals]

If you have specific questions about settings and/or circumstances, just ask. I'm usually less snarky, sorry.