Basengreen battery problem

[Great Dane]

Hi there

I recently bought a 12v Lifepo 100 Ah battery from Basengreen EU warehouse. This thing is giving me a headache.


The problem is that I can´t charge the battery without getting a cell overvoltage shutdown.
When cell 1 gets around 3.480V it runs of, and soon after the bms shuts down to protect the cells from over charging.


I´am using a Victron 100/50 solar charger and using Victrons own Lifepo4 preset as a basis. I have tried several different
settings with the charger and the bms - all with the same results. I mean - how hard should it be to charge a simple battery?

I should be able to charge all 4 cells to around 3.65V, and without any cell overvoltage shutdown - no?

I reached out to Basengreen with my problem. This is their answers:

"The BMS will shut down because one cell will rise to 3.65V and the other cells will still be at 3.45V, but the battery will be fully charged."

"According to the screenshot you provided, the SOC of the battery is 100%, and the battery cell has reached the static full voltage, indicating
that the battery has been fully charged.
The voltage difference of cells is caused by the fact that some cells have reached the static full voltage, but they are still charging at this time,
and the voltage of some cells will suddenly rise (such as the cell 1 in your attachment), resulting in the voltage difference.
This is the characteristic of lithium iron phosphate.
If the battery is in static state (no charge, no discharge, stand for 6-7 hours), the pressure difference of the battery will not be more than 20mV.
Overall, this is a normal phenomenon."

So "Overall, this is a normal phenomenon" ?

Seems to me that these cells are not properly balanced?

The battery have a resting voltage (2 days after a full charge) at 13.32V is that not a little low?

I do not own a capacity tester, so I can´t comment on that.

So what do you guys think?

Thanks.


Settings (tried several different ones):

 

[Jordi]

To me the balancing feature means that when charging the battery, If the voltage difference of the cells (on average) goes beyond a certain threshold, the balancing will make the cell voltages similar again. As soon as you stop charging the balancing feature deactivates and the cell voltage difference may increase.

Thus cell voltage difference when charging is completed is normal, but while charging should be less normal.
I base this observations on my Daly BMS.

 

[Sverige]

How long has this problem persisted for? Clearly the cells are out of balance, but as the balancer only has time to perform balancing for a short time each cycle, you should allow it some cycles to correct the problem before concluding the battery is faulty. Setting the “balancer configuration/ start voltage” to a lower level will help the balancer spend longer balancing at the top of each charge, but maybe not necessary to change that setting if you would like to just wait 10-20 cycles and see whether the situation corrects itself without a change in settings.

 

[timselectric]

Lower the charging amps from the charger. To give the BMS more time to keep up with the balancing.

 

[DJSmiley]

The balancer is a passive one, so that takes forever. Also when only balancing during charge it can take even longer.

I would recommend setting the balancer start voltage to 3375 or so and disable balance only during charging (so it continous balances) and leave that for a few days

 

[Great Dane]

How long has this problem persisted for? Clearly the cells are out of balance, but as the balancer only has time to perform balancing for a short time each cycle, you should allow it some cycles to correct the problem before concluding the battery is faulty. Setting the “balancer configuration/ start voltage” to a lower level will help the balancer spend longer balancing at the top of each charge, but maybe not necessary to change that setting if you would like to just wait 10-20 cycles and see whether the situation corrects itself without a change in settings.

This problem has persisted from day one.

 

[Great Dane]

Lower the charging amps from the charger. To give the BMS more time to keep up with the balancing.

Yes I have done that, but I think it will take a long time before the cells are balanced.

 

[Great Dane]

The balancer is a passive one, so that takes forever. Also when only balancing during charge it can take even longer.

I would recommend setting the balancer start voltage to 3375 or so and disable balance only during charging (so it continous balances) and leave that for a few days

Will try that.

 

[Great Dane]

I´am just pissed that Basengreen sent me a battery that is out of balance. I guess their warranty is not worth much.

 

[LakeHouse]

I should be able to charge all 4 cells to around 3.65V, and without any cell overvoltage shutdown - no?

In practice, not likely. Even very, very well balanced cells won't all hit 3.65V at the same time. But, from your screenshot, I would agree with Basen that it shows your battery fully charged. Or at least 99% charged - there's very little capacity to be gained from 3.45V to 3.65V.
Also, you have your cell overvoltage set to 3.6V, so the BMS wouldn't allow even a single cell to get to 3.65V. To be clear, I'm not recommending you change that, 3.6V is fine for that setting.

Lower the charging amps from the charger. To give the BMS more time to keep up with the balancing.

Alternatively, you could lower the absorption voltage to 13.9V and increase the absorption time to give it more time to balance. That way you wouldn't have to limit bulk charging amps. I would treat this change as temporary though, and once the cells are balanced to your liking, switch back to your current 14.0V for 1 hour absorption scheme.

Seems to me that these cells are not properly balanced?

They aren't perfect, but I'd say it looks like the balance isn't terrible. The lowest cell at 3.435 is high enough voltage to be on the knee of the charge curve, so it's well over 90% charged. If that low cell was at 3.3 or 3.35, then yes the cells would look far out of balance.

 

[LakeHouse]

For context, this is 3.425V on a typical LFP charge curve:


EDIT: It’s a little hard to see, but it’s way over on the right side, right near the end of the test.

 

[Great Dane]

In practice, not likely. Even very, very well balanced cells won't all hit 3.65V at the same time. But, from your screenshot, I would agree with Basen that it shows your battery fully charged. Or at least 99% charged - there's very little capacity to be gained from 3.45V to 3.65V.
Also, you have your cell overvoltage set to 3.6V, so the BMS wouldn't allow even a single cell to get to 3.65V. To be clear, I'm not recommending you change that, 3.6V is fine for that setting.

Alternatively, you could lower the absorption voltage to 13.9V and increase the absorption time to give it more time to balance. That way you wouldn't have to limit bulk charging amps. I would treat this change as temporary though, and once the cells are balanced to your liking, switch back to your current 14.0V for 1 hour absorption scheme.

They aren't perfect, but I'd say it looks like the balance isn't terrible. The lowest cell at 3.435 is high enough voltage to be on the knee of the charge curve, so it's well over 90% charged. If that low cell was at 3.3 or 3.35, then yes the cells would look far out of balance.

Thanks LakeHouse will try that. Yes I changed the cell overvoltage to 3.6V to be on the safe side.

 

[timselectric]

Yes I have done that, but I think it will take a long time before the cells are balanced.

Yes, it could.

 

[fotovolt]

I have the same problem with basengreen 12V 230A

 

[dragonzzr]

I also have the same problem.
Solution for me was to just lower the charge voltage to 13.8 and also start the balancing at 13.8/4=3.45V per cell. Also, letting some "steam" off, i.e drawing for a few minutes even 5A or 10A load when the pack has reached 13.8V, seems to make the cells balance within 5mV or even 1mV for the whole battery.