Advice requested for charging a single 60AH cell with a bench power supply.

[scott harris]

I have recently purchased four 60Ah fortune cells and am trying to charge them individually with a 30v 10A bench power supply. I set the ps to 3.62 volts and connected it to a cell. At first it drew close to 10 amps. Now after about 10 hours it is drawing 2.7 amps. I want to charge it to 100% so that I can do a capacity check. So how low should the charging current be to assure 100% SOC?

 

[Ampster]

Less than one Amp. More importantly, use the same value for each cell. Do you have a way to measure Ahrs into battery? Probably not many Ahrs between 2.9 and 1.

 

[scott harris]

I do have a battery monitor but I didn't connect it because I figured that I did not know the initial SOC.

Can I leave the cell connected to the charger indefinitely? Will it just stop charging when it is full, or will prolonged charging (24 hours) at 3.62 volts at low current cause a problem?

 

[Ampster]

You do not want to leave Lithium cells at that voltage for many days. The current will continue to taper but it is like going half the distance to a wall with each step. Pretty soon the steps keep getting smaller and smaller. Start logging time and Amps and when it gets slow you can do the test. A few Ahrs one way or the other won't matter. Just note the ending Amps so if you do another cell you are consistent.