Problems Testing Eve LF280 with Ebc a40l

[Dave (Boog)]

I am trying to test Eve 280 cells using my Ebc-A40l tester.
Just a note, I have already tested 8 Lishen 272ah cells with this same tester without any issues at all.
However as soon as I attempted to run the same discharge and charge test on my Eve 280 cells I am having problems.
Both the Lishen and Eve cells have been in boxes since I received them in May 2021. Unfortunately I’ve been too busy to do anything with them.
When I try to run a discharge on a cell at 40 amps the test automatically turns off. See the first screen grab. The amps on the chart instantly falls to zero.
Only when I lower the amperage to 20 amps does it let me discharge these cells.
These are 280 ah cells and I can see no reason why I can discharge them with 40 amps? The Lishen cells discharged at 40 amps with no problem.
Any ideas? I’m stumped? How can I test these cells to be sure they are ok before I build my battery?

 

[RCinFLA]

Are you using the remote cell voltage sensing? Voltage needs to be sensed right at the cell terminal posts.

 

[Dave (Boog)]

Are you using the remote cell voltage sensing? Voltage needs to be sensed right at the cell terminal posts.

Yes the voltage sense lead is connected.

 

[MisterSandals]

Why are you doing a discharge test from an unknown mid to low level state of charge?

Seems like charging to full and then doing a discharge would give a meaningful capacity test number.

 

[Dave (Boog)]

Bump

 

[Dave (Boog)]

Why are you doing a discharge test from an unknown mid to low level state of charge?

Seems like charging to full and then doing a discharge would give a meaningful capacity test number.

That might be a valid question, but I’m not sure that answers my question of why I can’t discharge these 280 ah cells at 40 amps when these are rated at a max discharge of 1C.

 

[MisterSandals]

but I’m not sure that answers my question of why I can’t discharge these 280 ah cells at 40 amps

Your cell might be at a low state of charge and 40A causes voltage slump down to your 3.0V cutoff.
Just a guess without any info on your battery SoC.

 

[Dave (Boog)]

Your cell might be at a low state of charge and 40A causes voltage slump down to your 3.0V cutoff.
Just a guess without any info on your battery SoC.

Thanks for your thoughts. The cell voltage was at 3.231 volts according to the tester, but according to two different meters I checked the cells with, the voltage was 3.321 volts. Not sure why the discrepancy. I was just worried maybe the cells are damaged after sitting for almost 3 years without being charged or discharged. But they shouldn’t be damaged unless the voltage fell below 2.5 volts? I have checked them a few times a year since I bought them and never saw them below 3.2 volts at anytime.

 

[Dave (Boog)]

I managed to discharge the cell down to 2.55 volts by lowering the discharge amps to 20. Now I’m trying to charge them up to 3.45 volts. But I noticed the charge curve seems strange, and not what I expected.
After around 40 minutes the cell was already at 3.45 volts from a starting voltage of around 2.6 volts.
Attached is a screen grab of the charge curve after about 2 hours. Looks weird to me! At a 40 amp rate it should take around 7 hours to fully charge.

 

[MisterSandals]

Looks weird to me! At a 40 amp rate it should take around 7 hours to fully charge.

That is strange. The cell is only accepting 23.1A
280Ah / 23.1A = 12.12h

But as the cell fills, it will accept less and less current. I'd be interesting to see how the current level drops over time. When it accepts under an amp, it should be full.

 

[Dave (Boog)]

I just went to the basement to check the voltage of the cell I’m charging. The cell measured 3.37 volts and not the 3.45 volts the tester thinks it’s at. I wonder if that accounts for the weird looking charge curve? I’m monitoring the charge from my master bedroom remotely on my iPad so I can stay warm. It’s too damn cold in the basement!

 

[MisterSandals]

The cell measured 3.37 volts and not the 3.45 volts the tester thinks it’s at.

You really need to measure voltage at rest.

Imagine filling a bucket of water from a faucet. If you measure upstream of the faucet, the pressure will be household pressure (lets say about 30PSI). If you measure that same water stream after the faucet, the pressure will be nearly zero. If you measure somewhere in the faucet, it will be somewhere between the two.

So your charger is 3.45V and its connected to a 3.37V battery. The voltage on the wires/devices between them has to be somewhere in-between.

 

[Dave (Boog)]

You really need to measure voltage at rest.

Imagine filling a bucket of water from a faucet. If you measure upstream of the faucet, the pressure will be household pressure (lets say about 30PSI). If you measure that same water stream after the faucet, the pressure will be nearly zero. If you measure somewhere in the faucet, it will be somewhere between the two.

So your charger is 3.45V and its connected to a 3.37V battery. The voltage on the wires/devices between them has to be somewhere in-between.

Makes sense, I’m not sure I trust what the tester is telling/showing me. I’m just going to charge the cells up and top balance them. Then I’m going to build a 24 volt battery with them, hook them up to an inverter I have and discharge them with a load and see what results I get. Worst case, all 8 cells are garbage and I’ll have to recycle them. I’ll be out $1000, but live and learn I guess.

 

[Dave (Boog)]

Figured out why everything was screwed up. The EBC A40L is bad! I bought another to compare and everything is working fine now. Charging, discharging, the graphs, everything! Not sure what’s wrong with my original tester, but I guess I have an expensive paperweight!!!

 

[Dave (Boog)]

Figured out why everything was screwed up. The EBC A40L is bad! I bought another to compare and everything is working fine now. Charging, discharging, the graphs, everything! Not sure what’s wrong with my original tester, but I guess I have an expensive paperweight!!!

I might have to take the bad A40L apart to see if I can troubleshoot the problem with it.