Are these stubborn calls?

[Roswell Bob]

I have 4 of the EVE 280Ah calls in series. No BMS yet.. I am putting 20A into pack. Power supply current meter agrees with DC clamp on and 30A fuse is as warm as I would expect. After 2 hours at 20A not one of the cells has moved up a millivolt. My guess is they should have moved close to 150mV.

Any ideas?

 

[sunshine_eggo]

I have 4 of the EVE 280Ah calls in series. No BMS yet.. I am putting 20A into pack. Power supply current meter agrees with DC clamp on and 30A fuse is as warm as I would expect. After 2 hours at 20A not one of the cells has moved up a millivolt. My guess is they should have moved close to 150mV.

Any ideas?

Very common. Almost all charging occurs at lower voltage levels. The curve is truly flat. You have 140Ah to input, so another 5 hours to go.

 

[Roswell Bob]

Very common. Almost all charging occurs at lower voltage levels. The curve is truly flat. You have 140Ah to input, so another 5 hours to go.

Ok,that is Great news. I suppose that is why we count coulombs. When the pack is near full voltage should rise to 3.65v?

 

[S Davis]

My first EVE 280ah four cell pack top balancing in parallel took 72 hours and the second 76 hours with a 10 amp power supply.

 

[TomC4306]

Ok,that is Great news. I suppose that is why we count coulombs. When the pack is near full voltage should rise to 3.65v?

You will start seeing faster movement once it gets above 3.38 or so.

WHY DON'T YOU HAVE A BMS ON IT?

Watch very carefully. 10 hours from 3.2 3.3. 5 from 3.3 to 3.4.
1 hour from 3.4 to 3.65 (or overvolt a cell)

The charge curve becomes logarithmic.

 

[Whinny]

You mention you are charging 4 cells in series? With no bms?
I would suggest stopping now.....
4 in paralell is ok to 3.65

 

[sunshine_eggo]

You will start seeing faster movement once it gets above 3.38 or so.

WHY DON'T YOU HAVE A BMS ON IT?

+1000

I missed this.

If you're watching it like a hawk, fine... I mean literally checking it every few minutes.

I would stop after 5 hours regardless. That's 100Ah in vs. a likely 140Ah needed.

 

[Roswell Bob]

Thank you all. I will put BMS on it