OH NO!!?? Have I killed my LifePO4 batteries?

[rfguy]

I just installed in my RV those same batteries but did it in a 4S4P configuration with a single 200A BMS. I have to wonder (no claim to be an expert) when you assembled yours you made 2 2S4P packs. Did you use 2 BMS or one? You had to jumper the parallel cells if only one BMS. To your problem, I would check the voltage of each cell pair of each pack and see how well they are matched. Your pack since it went dead or very low SOC may be very unequal such that the BMS is shutting down??

 

[rfguy]

I just installed in my RV those same batteries but did it in a 4S4P configuration with a single 200A BMS. I have to wonder (no claim to be an expert) when you assembled yours you made 2 2S4P packs. Did you use 2 BMS or one? You had to jumper the parallel cells if only one BMS. To your problem, I would check the voltage of each cell pair of each pack and see how well they are matched. Your pack since it went dead or very low SOC may be very unequal such that the BMS is shutting down??

Correction above I meant instead of 2S4P really needed to say 4S2P. sorry

 

[gnubie]

Checking cell pack / cell voltages is definitely a good idea though. That'd at least highlight a problem with the voltage of one of them going high and tripping the BMS, despite the overall low SOC of the battery.

 

[Daz]

My setup uses 2x 125A BMS, one on each 2S4P block. It's been another 16 hours on the 45A charger and the charging rate is up to 4.9A. That's a big improvement from the earlier 0.04x charging rate!

If it's in a safe rebuilding mode, is that controlled by the BMS or the charger I wonder?

The app is reading:
Bank 1: 3% / 12.47V / cells from 3.107 - 3.126
Bank 2: 4% / 12.47V / cells from 3.096 - 3.138

I guess the plan for now is leave it as is and see if the charging rate increases as they get closer to or over 10%.

It's 10am, the rain clouds are gone and it looks like a partially cloudy day. Who knows how some solar charging might affect things....

Cautiously optimistic.

 

[Daz]

I just noticed that the BMS app has a toggle in the settings. "Charging port on when battery off" - yes or no.

Any informed advice on switching this on? Would it interfere with overcharge protection?

 

[rfguy]

My setup uses 2x 125A BMS, one on each 2S4P block. It's been another 16 hours on the 45A charger and the charging rate is up to 4.9A. That's a big improvement from the earlier 0.04x charging rate!

If it's in a safe rebuilding mode, is that controlled by the BMS or the charger I wonder?

The app is reading:
Bank 1: 3% / 12.47V / cells from 3.107 - 3.126
Bank 2: 4% / 12.47V / cells from 3.096 - 3.138

I guess the plan for now is leave it as is and see if the charging rate increases as they get closer to or over 10%.

It's 10am, the rain clouds are gone and it looks like a partially cloudy day. Who knows how some solar charging might affect things....

Cautiously optimistic.

Hello Daz-The cell voltage does not seem all that low and you may not have damaged them. I think if this were my packs I would remove all loads and BMS wires and remove all series jumpers and attempt to get the cell voltages closer. Again I am not an expert but I think your cell voltages are close enough to connect all 16 in parallel and let them stay that way for 8 hrs of so. once they are all leveled your BMS may handle the charging better. When I got my Fortune cells I verified they were all within .05V and connected them in parallel until I was ready for them. Anyway your cells voltages are far apart -in my opinion. Will posted on this forum block the suggested profile for LiFePO4 as bulk charge voltage 14.5 and float 13.6.

 

[John Frum]

Hello Daz-The cell voltage does not seem all that low and you may not have damaged them. I think if this were my packs I would remove all loads and BMS wires and remove all series jumpers and attempt to get the cell voltages closer. Again I am not an expert but I think your cell voltages are close enough to connect all 16 in parallel and let them stay that way for 8 hrs of so. once they are all leveled your BMS may handle the charging better. When I got my Fortune cells I verified they were all within .05V and connected them in parallel until I was ready for them. Anyway your cells voltages are far apart -in my opinion. Will posted on this forum block the suggested profile for LiFePO4 as bulk charge voltage 14.5 and float 13.6.

I suggest we identify the problem if possible before making any changes.
@Daz please check each cell with a meter and record the voltage.
compare the readings with your bms to see if they agree.

 

[rfguy]

I suggest we identify the problem if possible before making any changes.
@Daz please check each cell with a meter and record the voltage.
compare the readings with your bms to see if they agree.

I agree use a meter first on each cell.

 

[John Frum]

My setup uses 2x 125A BMS, one on each 2S4P block. It's been another 16 hours on the 45A charger and the charging rate is up to 4.9A. That's a big improvement from the earlier 0.04x charging rate!

If it's in a safe rebuilding mode, is that controlled by the BMS or the charger I wonder?

The app is reading:
Bank 1: 3% / 12.47V / cells from 3.107 - 3.126
Bank 2: 4% / 12.47V / cells from 3.096 - 3.138

I guess the plan for now is leave it as is and see if the charging rate increases as they get closer to or over 10%.

It's 10am, the rain clouds are gone and it looks like a partially cloudy day. Who knows how some solar charging might affect things....

Cautiously optimistic.

Do you have a shunt based battery monitor?
It would be good to know how much current is going into the batteries.
At that state of charge the batteries should be drawing as much current as the charger can supply.

 

[John Frum]

Do you have a shunt based battery monitor?
It would be good to know how much current is going into the batteries.
At that state of charge the batteries should be drawing as much current as the charger can supply.

I want to independently verify the current flow into the battery.

 

[Daz]

I want to independently verify the current flow into the battery.

Yes, I have a shunt based monitor. The readings on it are charge draw of 4.94A / 17.2% charge / 12.51V
The BMS are showing a charge rate of 1.99A / 1.97A but a charge state of 3% - 4% and 12.47V.

Hard to know which is the most trustworthy.

 

[John Frum]

Yes, I have a shunt based monitor. The readings on it are charge draw of 4.94A / 17.2% charge / 12.51V
The BMS are showing a charge rate of 1.99A / 1.97A but a charge state of 3% - 4% and 12.47V.

Hard to know which is the most trustworthy.

Please post pictures of your setup.
If it's to big for detail or disperse post multiple pics.
It like your battery has limp home mode.
Never heard of one that did though.

 

[John Frum]

Please post pictures of your setup.
If it's to big for detail or disperse post multiple pics.
It like your battery has limp home mode.
Never heard of one that did though.

You said "are" which is plural.
If you have 2 batteries in parallel each with its own bms then this makes sense.

 

[rfguy]

Yes, I have a shunt based monitor. The readings on it are charge draw of 4.94A / 17.2% charge / 12.51V
The BMS are showing a charge rate of 1.99A / 1.97A but a charge state of 3% - 4% and 12.47V.

Hard to know which is the most trustworthy.

Typically on your shunt there will be markings as to its calibration something like 50mV per 100A or such just an example. This would allow you to calculate the current with a separate volt meter and not rely on the monitor. My cells from the vendor were all 3.28V individualy and when I connected my Xantrex it began bulk charging at 80A (the charger capacity) until the pack reached 14.5V then tapered off to float.

 

[Daz]

You said "are" which is plural.
If you have 2 batteries in parallel each with its own bms then this makes sense.

That's what I have. One shunt / monitor.

I said "are" because I was referring to a number of values.

 

[John Frum]

That's what I have. One shunt / monitor.

I said "are" because I was referring to a number of values.

Ok then your battery monitor is showing over double the current that your bms is showing.
Not good at all.

 

[John Frum]

Should I wait for pictures?

 

[Daz]

The battery monitor is showing the total charging A of what the app shows for each BMS.

And I found the source of the continued slow charging issue. The outlet I had the charger plugged into, was wired through a light switch! (old garage). lol. The garage light was on when I plugged in the charger, the charge was running, then I would lock it up and turn off the lights...... omg.

Now, each BMS is showing 22.5A and the Monitor is showing +/- 45A.

The BMS tells me the batteries are still at 11%, but now that they're taking some decent amps, I'm only waiting to see how it is when they get closer to full.

Oh, and the balance figures are tightening up too: 3.270 3.272 3.275 3.279 (one bank).

 

[rfguy]

The battery monitor is showing the total charging A of what the app shows for each BMS.

And I found the source of the continued slow charging issue. The outlet I had the charger plugged into, was wired through a light switch! (old garage). lol. The garage light was on when I plugged in the charger, the charge was running, then I would lock it up and turn off the lights...... omg.

Now, each BMS is showing 22.5A and the Monitor is showing +/- 45A.

The BMS tells me the batteries are still at 11%, but now that they're taking some decent amps, I'm only waiting to see how it is when they get closer to full.

Oh, and the balance figures are tightening up too: 3.270 3.272 3.275 3.279 (one bank).

Excellent! Sounds like you got it under control. Like I said earlier I bought the same number of Fortune batteries and they took an 80A charge for several hours. Make sure you only charge them to a pack total of 14.5V which should end up with cells at 3.63V just under the max. Good luck!