No announcement yet.

BMS with T connection

  • Filter
  • Time
  • Show
Clear All
new posts

    BMS with T connection

    bit of a different topic but wasn't sure what Forum I could ask in.
    I'm disassembling a speaker as I accidentally connected it to power with the wrong polarization which made the charging circuitry on the main PCB blow up. The rest of the PCB still functions perfectly as in it still plays music normally from battery power I just can't charge it.

    So I bought a different BMS for the 3S1P Battery pack inside the speaker, with onboard charging circuitry so that I can just skip the original broken onboard charging circuitry all together and connect the charging port straight to the New BMS. Now I have connected the new BMS welded everything together. Soldered the wires to the BMS just as it's meant to be and the speaker "turns on" no problems.

    However here's the problem the old original BMS had three connections Positive Negative and "T". The new BMS only has Positive and Negative, meaning the "T" wire currently isn't connected to anything.
    As mentioned the speaker turns on and the lights go on HOWEVER, it doesn't properly start as in Bluetooth doesn't turn on or anything else, SOMETIMES when I connect the "T" wire to ground with a 1Kohm resistor it turns on without any issues and plays music as it's meant to, however when I then disconnect it again it instantly "turns off" or rather shuts down as in the lights are still on but seems to be in some sort of protection mode where everything including Bluetooth is off but some parts are still on like for example the LEDs indicating that it's on.

    So the problem is I don't know what the "T" wire is for, what it's function is and therefore how to connect it.

    I was thinking either it's a "T"emperature connection using a simple resistance based temperature detection. So I measured the resistance of the "T" connection to ground on the old BMS which was around 1Kohm hence I used the 1Kohm resistor to ground to simulate a normal operating temperature, as mentioned with that it SOMETIMES but only rarely turns on.
    Another thing the "T" connection could be is a "T"est connection, as in testing for the battery level and then the speaker decides if it should turn on or not. However there I wouldn't know what I would have to do to spoof the Speaker into thinking that everything is fine, so that it operates normally.

    Anyone have any ideas what the "T" connection is for how I can spoof a signal for it so that the speaker functions normally?

    As mentioned with the original BMS with the fried charging circuitry it would still work perfectly fine and turn on when I turned it on and played music normally no problems whatsoever. it's just having problems because of the new BMS I put in and the not connected "T" cable/wire.