New Battery Has Odd Cell Readings From Bluetooth BMS

[newbieNeedsHelp]

Hello and thanks in advance to anyone willing to provide some input about my issue.

Ordered a new battery off Amazon called PUPVWMHB which is a 12V 100Amp Hour Bluetooth battery using a DGJBD BMS (Firmware Version 44, Device Name JBD-SP04S034-L4S-100A). I downloaded a few apps and am seeing some odd results for the current status of the battery. I have a LiFePO4 charger that I also bought off Amazon that can charge at a rated capacity of 20Amps. According to my charger the battery showed up almost at full charge (but I've been charging this things for about 4 hours now). Also this same charger did a great job on my 50Ah lithium battery so I at least know the charger works.

According to the charger the battery is charging at around 12.6Amps, and the App I downloaded says 12.2-12.4Amps so this is probably reading okay on both ends. The part that is scaring me a bit is that the BMS does not show that any balancing is on (Not sure if I understand exactly what this means as I've got only a single battery, but the battery has 4 cells in it). The Cells Read as follows Cell 1. 0.228v (fluctuates a bit up and down), Cell 2. 0.044v (Does not change at all and has had this reading the entire time charging), Cell 3. 2.61v-2.66v, Cell 4. 1.11-1.47. There are also two alarms showing the first being Cell Undervoltage Protection, and the second is Battery Undervoltage Protection. Should I simply let this thing charge overnight or am I dealing with a faulty battery here? Another question is since the two alarms are on, should I buy a pro-version of one of these apps and change a setting in the BMS?

 

[newbieNeedsHelp]

Okay, so the charger said the battery is now full, and I am looking in the app for the battery which reads 4.22V total power? There's got to be something wrong with this thing. Just hooked it up to a 12V 30amp Trolling Motor as a quick and easy test and nothing happened . Pretty sure this battery is a dud unless someone else has some ideas?

 

[newbieNeedsHelp]

So the manufacturer has responded and asked a few basic questions. We'll see if this manufacturer really will stand behind what they are selling. Figured this battery would not be top notch, but enough for the low power applications I have. Was able to see around 12Amps of charging current, but that now will drop to 1.5Amps and my charger shuts off. Have tested again on my 12v 50Amp LiFePO4 battery and the charger is working fine.

 

[400bird]

If those voltage numbers are real, and I have no reason to doubt them, that battery is garbage. Minimum cell voltage is 2.5 volts, it should never ever go below 2.5 volts.

 

[newbieNeedsHelp]

They are now asking me to charge the battery they sold me in parallel with my 12V 50Ah LiFePO4 battery. It's pretty annoying as I have to buy new cables which won't be here until tomorrow to do that. Plus, I'm not really interested in risking my other battery to fix the garbage they sent me. Plus, I did notice when I charged the battery at first all the cells except Cell 2 changed their values at least a little bit, while Cell2 is stuck exactly at 0.04v. I'm probably going to just send it back.

 

[400bird]

I'm probably going to just send it back.

I would
Those cells got low enough they have lost some capacity and may never be the same.

 

[RCinFLA]

Charger is likely saying full because BMS has shut down charging because of out of range low voltage on some cells. Many BMS's will not allow charging at any charge rate greater than a few hundred mA's, if a single cell voltage is below 1.0 to 1.5 vdc. The reason is safety as a super low voltage cell may have internal shorts that can heat up cell if high charge current is pushed through it.

No lithium-ion cell should be allowed to get to 0.04v. That causes lithium dendrite growth that will eventually short out cell.

If cell voltage readout is correct the battery is defective. At only 4.03v battery terminal voltage, I would be surprised if BMS works without an external charger to provide enough supply voltage to run BMS. Do you see any BT readings from BMS when not connected to charger?

 

[newbieNeedsHelp]

Charger is likely saying full because BMS has shut down charging because of out of range low voltage on some cells. Many BMS's will not allow charging at any charge rate greater than a few hundred mA's, if a single cell voltage is below 1.0 to 1.5 vdc. The reason is safety as a super low voltage cell may have internal shorts that can heat up cell if high charge current is pushed through it.

No lithium-ion cell should be allowed to get to 0.04v. That causes lithium dendrite growth that will eventually short out cell.

If cell voltage readout is correct the battery is defective. At only 4.03v battery terminal voltage, I would be surprised if BMS works without an external charger to provide enough supply voltage to run BMS. Do you see any BT readings from BMS when not connected to charger?

Yes, these are the readings from the unit whether it is charging or not. Really makes no difference on the cell at 0.04v. The other cells have their voltage readings change at least a little bit while charging but seem to come back to the same values. The 0.04v cell does not fluctuate at all. The BMS does work over Bluetooth though even at this voltage so it could be that they didn't install something correctly. When I first got the battery both the charger and the BMS were reading that the battery was charging around 12Amps. Then after a while it dropped to 1.5Amps and instead of saying "Full" on the charger LED read out, it read "Off".

Thanks for the advice. I'm going to return it.