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Help with a battery


1 µW
May 3, 2024
United Kingdom
Hi all, unsure where to even ask this question so hoping someone might help.

Got a battery out of an electric scooter which won't take charge. After probing around, the cells do have voltage (slightly under what they should be, but if it's not charging that's gonna be about right).

Issue i can see, is the two negative connections to the charging port and the output to motor are dead... multimeter doesn't show continuity back to main battery negative. Probing the positives (at the same end) to the main battery neg does show voltage so the cells are definitely live though.

Any ideas? Very unfamiliar with this type of board, never really worked on BMS before.

Thanks in advance!

(thick wires to motor, thin are charging wires, both red pos show voltage back to B- on main board but not on their own negative wires)
You're going to have to give us some information where did you get the battery does it have a name on it do you have a link for the battery how many voltage is it
More info besides a battery.
This seems to be a 10s pack, probably the BMS shut down due to low battery voltage, you need to read voltage between “B-“ tab and “B10” tab, If you get the pack voltage is the BMS that is disabled.

You should also read and take note of all series, so read b- to b1 and take note of voltage, b1 to b2 and take note of voltage, etc etc .
This is a typical BMS . Shown for a 36V battery, It is also shown for a two port BMS, which has a separate charge and discharge. If the battery has a combined charge/discharge, then there is only one transistor circuit,

The BMS is measuring the voltage on all ten cell groups, and expects them to be between 3.0 and 4.2V. If any are too low, the BMS disables the battery by opening the switches. It's also got circuitry to measure temperature,. and looks for short circuit currents. These also shut off the battery,

Portugaline has pointed out that the B0 thru B10 points are labeled on the BMS. You need to measure B10-B9, B9-B8, ..., all the way down to B1-B0, Those are the ten cell voltages. They will tell you the health of the battery, Ideally, all are close to each other (balanced) and between 3.0-4.2 Volt. Do it and give a report.

Work carefully, There's a lot of energy in a scooter battery, Don't let the cell terminals touch anything that could short them out,
After probing around, the cells do have voltage (slightly under what they should be, but if it's not charging that's gonna be about right).

What per-cell voltage are we talking about? If it's outside the BMS's bounds, it will cut off so you don't do something regrettable.