Connect battery backward, battery shorted on tsdz2b, need help !

[vviettan]

Hi everyone, I am new here. First of all, sorry for my English. I really need some suggestion... Can't imagine how stupid am I .
I have a Tongsheng tsdz2b kit and 48V-19.2Ah battery.
I accidently connect the battery to the motor in backward (positive to negative) . I heard a little kick sound from the motor when I power on the battery. I tried to press the power button on my 850c display but it kept being off.
The power cable from the battery to the motor was warn when I touched it (huge current flowed through it). I realized I was doing something wrong. I unpluged the power cable out of the motor and found out that it was connected in backward.
I pressed the button power indicator button on the battery to check the battery status. There was only one red led out of 4 leds light up (it were 3 greens and 1 red before the accident)
I tried to connect battery to the motor correctly. There was no hope, the screen kept being black (.
I plugged my 5V lamp to the usb port on the battery, it worked, the lamb turned on. However I found out the power button (switch) on the battery doesn't work anymore as I turn it off but the lamp was still on.
I tried to charge the battery overnight (for 6h). Then I connect it to the motor again but still no hope. The thing is the led indicator on the charger was green when I plug it to the battery, meaning there was no charge current to the battery.
Now I don't know whether my motor or my battery is still alive. I hope there was some protection mechanism to cutoff the circuit during the accident.
You can see in the photo, the system was totally fine the night before the accident.
I post here to look for any suggestion… The thing is I have no experience on the tsdz2 system because I have just bought the motor and battery a few days ago, haven't install it on the bike yet . I appreciate all of your comments. Thanks!

 

[beemac]

Hi everyone, I am new here. First of all, sorry for my English. I really need some suggestion... Can't imagine how stupid am I .
I have a Tongsheng tsdz2b kit and 48V-19.2Ah battery.
I accidently connect the battery to the motor in backward (positive to negative) . I heard a little kick sound from the motor when I power on the battery. I tried to press the power button on my 850c display but it kept being off.
The power cable from the battery to the motor was warn when I touched it (huge current flowed through it). I realized I was doing something wrong. I unpluged the power cable out of the motor and found out that it was connected in backward.
I pressed the button power indicator button on the battery to check the battery status. There was only one red led out of 4 leds light up (it were 3 greens and 1 red before the accident)
I tried to connect battery to the motor correctly. There was no hope, the screen kept being black (.
I plugged my 5V lamp to the usb port on the battery, it worked, the lamb turned on. However I found out the power button (switch) on the battery doesn't work anymore as I turn it off but the lamp was still on.
I tried to charge the battery overnight (for 6h). Then I connect it to the motor again but still no hope. The thing is the led indicator on the charger was green when I plug it to the battery, meaning there was no charge current to the battery.
Now I don't know whether my motor or my battery is still alive. I hope there was some protection mechanism to cutoff the circuit during the accident.
You can see in the photo, the system was totally fine the night before the accident.
I post here to look for any suggestion… The thing is I have no experience on the tsdz2 system because I have just bought the motor and battery a few days ago, haven't install it on the bike yet . I appreciate all of your comments. Thanks!

Hi - unfortunately sounds like you've probably fried the battery and/or controller in the tsdz2. Battery may have a BMS that current limits the output but if the cable to the motor was warm from current then I doubt if it's limited anything... only time I shorted a battery I fried the BMS and two parallel groups in the battery.

Only way to check is to open the battery and see what's going on with a multimeter.

If your charger is still working - you could use that as a power supply to test whether the motor/controller/display is broken.

 

[amberwolf]

Do you have a multimeter you can do some testing with? If so, we can probably help you find the problems, at least, once we get a little more detail from you. See below for notes on where the problems may be. If you think you can work on the parts, then we can start helping you troubleshoot.

The power cable from the battery to the motor was warn when I touched it (huge current flowed through it).

With reversed power across a controller, the FETs act as diodes, basically shorting out the battery, so very high current flows thru the FETs and heats them up a lot. The electrolytic capacitors (like little cans) on the controller also heat up and can be damaged or fail from this. There may be no obvious sign of damage, or the parts may actually explode. The current measuring shunt in the controller is also in the current path so it may get so hot that it melts it's solder and comes off the board--in this event the controller may no longer get any power so even if it's functional and not damaged other than the solder, it appears dead.

If the FETs / caps are failed they can usually be replaced and fix that part, but:

There is also a low-voltage-power-supply (LVPS) in both the controller and a separate one in the display that can be damaged from this as well. This may be harder to repair.

But to test those things you'll need to fix the battery first:

I pressed the button power indicator button on the battery to check the battery status. There was only one red led out of 4 leds light up (it were 3 greens and 1 red before the accident)

That may mean the BMS has shut off it's output to protect the battery, or that the BMS output FETs are actually damaged so it can't output correctly. This can also damage the charge FETs if they are in the same circuit (common-port BMS), so the battery will appear not to charge either.

If there's a fuse past the battery check lights but before the output to controller, the fuse might be blown.

If a multimeter across the battery output wires reads 0V, it's probably a fuse (maybe more) blown.

If it reads a voltage but a lot lower than it should be, any fuse is probably still ok but the BMS is either shutdown or damaged.

Some BMS have a reset button or jumper on them, but you have to open the battery to get to that.

I plugged my 5V lamp to the usb port on the battery, it worked, the lamb turned on. However I found out the power button (switch) on the battery doesn't work anymore as I turn it off but the lamp was still on.

Then it's likely the battery cells are still ok, and all the interconnects inside. THat can be tested if necessary.

 

[vviettan]

Only way to check is to open the battery and see what's going on with a multimeter.
If your charger is still working - you could use that as a power supply to test whether the motor/controller/display is broken.

Thanks for your advice, I will test the motor with the charger

 

[vviettan]

Do you have a multimeter you can do some testing with? If so, we can probably help you find the problems, at least, once we get a little more detail from you. See below for notes on where the problems may be. If you think you can work on the parts, then we can start helping you troubleshoot.

Thank you very much for your reply. I have just bought the multimeter today. I will follow your instruction to test the battery then report it back here.

 

[vviettan]

If your charger is still working - you could use that as a power supply to test whether the motor/controller/display is broken.

Hi bro, I tried to test the motor with my 52V-4A charger, the display was able to say "Hello" for just 1 second then turned off. I think the charger is not powerful enough to power up the system. However, after fixing the battery, everything works well
Anyway, thank you for your comment!!!

 

[vviettan]

That may mean the BMS has shut off it's output to protect the battery, or that the BMS output FETs are actually damaged so it can't output correctly. This can also damage the charge FETs if they are in the same circuit (common-port BMS), so the battery will appear not to charge either.

I plugged my 5V lamp to the usb port on the battery, it worked, the lamb turned on. However I found out the power button (switch) on the battery doesn't work anymore as I turn it off but the lamp was still on.

Then it's likely the battery cells are still ok, and all the interconnects inside. THat can be tested if necessary.

Hi bro, you are right. The battery cells are still ok, only the BMS board is damaged. I found that the cupper material on the board is blown up, creating a opened circuit I believe. After solder the board, the battery is working. There is only the on-off button on the battery is malfunction. It does not cut off the power when I turn it off. The connectivity of the switch is okay so I think it is still shorted somewhere in the board. I am fine with it as everything else seems to be okay. The battery now can work well with the motor :wink: . I have closed the battery case then I will test the charging for sometime to see if there is any problem.
Thanks for your help!

 

[beemac]

If your charger is still working - you could use that as a power supply to test whether the motor/controller/display is broken.

Hi bro, I tried to test the motor with my 52V-4A charger, the display was able to say "Hello" for just 1 second then turned off. I think the charger is not powerful enough to power up the system. However, after fixing the battery, everything works well
Anyway, thank you for your comment!!!

Oh that's odd - should be plenty of current to drive the controller, display and run the motor at low power. I used my 2A charger all last winter doing dev work. It's possible with non-osf that it's the high-voltage shutoff - but not sure, main thing is you've got things working - glad it's not turned into a total disaster for you!

 

[amberwolf]

Hi bro, you are right. The battery cells are still ok, only the BMS board is damaged. I found that the cupper material on the board is blown up, creating a opened circuit I believe. After solder the board, the battery is working. There is only the on-off button on the battery is malfunction. It does not cut off the power when I turn it off. The connectivity of the switch is okay so I think it is still shorted somewhere in the board. I am fine with it as everything else seems to be okay. The battery now can work well with the motor :wink: . I have closed the battery case then I will test the charging for sometime to see if there is any problem.

If the power doesn't cut off when using the power button on the battery, it almost certainly means the BMS FETs were damaged in a way that leaves them always on (a common failure mode for FETs, often leaving no visible marks on them).

This failure mode means the BMS cannot turn off the output even if the pack is overdischarged or has some other problem, and probably also the input even if the pack is overcharged (or some other problem).

Testing for this problem with a multimeter without actually discharging the pack all the way to see if it turns off requires disconnecting all the wires to the battery except the main negative wire, to ensure that there's no voltage across the FETs during the test (because the test is done using the ohms function, which can be damaged by battery-level-voltages).