What volt / current rate to charge and test a single cell?

[davecason]

Hi,

I have a set of four standard LiFePO4 cells from Basen in China I used them on a road trip to power a fridge however since I got back they seem to be acting weird. (I know, very highly technical, right?) Yes, total newbie here .... hence, I'm in the right forum topic anyway .......

The stickers on them say:
3.2V LiFePo4 Cell
Capacity: 272 Ah
Voltage: 3.24 V
IR: 0.12 mOHM

Shenzhen Basen Technology Co., Ltd
Address, etc ......

My problem is I think my DALY controller is "unhappy" so I'd like to test / check each cell with my limited resources right now, so me buying a new controller is out till get one of those job thingy's ...... Can one of you folks confirm this suggestion below?

I was told that I can put my Nice Power bench supply on each cell at 3.65 v and 300 mh to see if they are OK. I did one cell for a couple of hours and it has come up, so it does take a charge but what should I be seeing with either the DVM meter or the display on the bench supply?




I set the supply up for 3.65 vdc out and .300 amps and let it run ...... but as for how valid this is as a suggestion and how long I should have the supply hooked up to a single cell, I have no clue. If you have any suggestions or some reading I can do to learn how to do it properly do it, it wild be much appreciated.

Cheers'
Dave

 

[#40Fan]

I'd suggest jumping on YouTube and looking for videos on how to accurately check these cells. Off Grid Garage has some great videos, but I caution not to get caught up in the shit he tries to sell. Or any YouTuber for that matter.

 

[davecason]

Hi 40Fan,

Cute timing I'm watching Andy right now ..........

My only question is really - what's a decent voltage and a mild but happy current I can use with my bench supply to try to top off these cells......
I was told 3.65 and .300 of an amp to slowly see if they'll hold anything ...... can I try .500 or half an amp instead?

As the cell gets towards a full SOC should the cell come up and read at that 3.65 after they are full or maybe stop at 3.50 on the bench supply?

OR did the guy who told me those values talking out of his bu...... (grin)

Cheers'
Dave

 

[chrisski]

These are 272 ah cells. If you charge at .3 amps, on an empty cell would take in excess of 700 hours to charge.

If the meter maxes out at 10 amps, over a day to charge.

I’d look at Videos on top balancing each cell. Likely they aren’t empty, so it won’t take over a day, but likely several hours each. If you set the voltage to 3.6 and amps to 10, then the CC will push 10 amps until the voltage climbs towards 3.6, and then the amps will taper off and once it reaches near 0, its full.

Important thing is to set the volts prior to attaching leads.

Secondly, make sure the wire leads can handle the amps. I threw the leads away that came with my power supply and made 10 AWG leads.