Daly BMS not booting

[TannyFordas]

Hey, so I've hooked up my 100A common port Daly BMS and despite the cells reading 74v across them the BMS is only reading 61v. When a load is put across the output of the BMS this voltage drops instantly to 0. Attempting to charge the battery though the BMS does nothing, as though the charger cannot even see the battery. As someone suggested online I attempted shorting the B- and p- terminals but nothing happened. Anyone got any suggestions?

 

[amberwolf]

The readings you see are because the BMS has shut off it's output, and input.

A BMS shuts off it's output whenever it detects overcurrent thru the pack, or undervoltage on a cell.

It shuts off it's input whenever it detects either overcharge on a cell, or severe undervoltage on a cell, too low to allow charge.

So the most likely things wrong are one of the cells or groups is way too low in voltage, or that it is wired wrong or has a connection problem so that it sees too low a voltage on a cell or group.

I'd start by checking the voltages *at the BMS PCB itself*, right on the solder joints of the connector, for each cell group, and list them in order from most negative to most positive. They should all be about the same voltage, within a few hundredths.

If any are really different, especially really low, then the BMS could be shut off because of that. Then you can check the cells at the cells themselves, to make sure they are really low or not. If they're not, then it's a connection between cell and BMS.

IF they are, then you can fix that by rebalancing the cells, but if they're reeally low, like 2v or less, I'd replace them as they may not be safe to use (and you won't know if there is a safety problem until they fail dramatically.

 

[VoltaireVolt]

Hey, so I've hooked up my 100A common port Daly BMS and despite the cells reading 74v across them the BMS is only reading 61v. When a load is put across the output of the BMS this voltage drops instantly to 0. Attempting to charge the battery though the BMS does nothing, as though the charger cannot even see the battery. As someone suggested online I attempted shorting the B- and p- terminals but nothing happened. Anyone got any suggestions?

Hey, I know it's been a while but the BMS of my e-scooter went out (I need it to go to work on monday), I have the same problem as you, did you find a solution, I'm not a professional so following Amberwolf's instruction is too difficult (Sorry in advance if I have made mistakes in my sentence I'm french and not too good at english) I will kindly wait for your answer, thank you

 

[amberwolf]

If your BMS turned off the output, it's to protect your cells against damage that can lead to a fire.

If you wish to fix the problem, you can either replace the entire battery pack, or you can open it up to test the cells to find out which one(s) are causing the problem. (and if no cells are causing the problem, then you can test connections and other things, but it is almost always bad cells).

If you don't want to do either one of those things, there's no good safe way to deal with the problem you have.

 

[VoltaireVolt]

If your BMS turned off the output, it's to protect your cells against damage that can lead to a fire.

If you wish to fix the problem, you can either replace the entire battery pack, or you can open it up to test the cells to find out which one(s) are causing the problem. (and if no cells are causing the problem, then you can test connections and other things, but it is almost always bad cells).

If you don't want to do either one of those things, there's no good safe way to deal with the problem you have.

I can see the voltage via the bluetooth device of the BMS and the highest voltage I can see is 3.804V on cell 16 and the lowest is 3.740V on cell 5, is that a big enough of a difference?