Fried Bafang BBS02?
- Thread starter halfeuro
- Start date
In your situation, I'd open up the controller and have a sniff. If you let out any magic smoke, you'll smell it. I don't know if the shunt is easy to see on a BBS02 controller, but if it fused open it would not necessarily stink.
dustNbone
10 kW
Which wires did you cut?
Shorting the power leads from the battery wouldn't hurt the controller, it's electrically equivalent to disconnecting it (voltage to the controller drops to zero or near it).
If somehow you managed to short high voltage battery power to one of the other lower voltage lines that come out of the motor (throttle, display, speed sensor, etc) that could well have blown something inside.
There's really no practical way to design for those kind of faults, making all the low voltage control circuitry tolerant of 60V would be extremely expensive, if it's possible at all. No way a fuse is gonna blow in time to avoid it.
The motor is probably fine though, it's possible high voltage made it to a hall sensor and nuked it but that's unlikely.
A fuse in the battery wouldn't necessarily save the BMS, only if it blew before anything on the BMS did.
Secure your wiring.
Shorting the power leads from the battery wouldn't hurt the controller, it's electrically equivalent to disconnecting it (voltage to the controller drops to zero or near it).
If somehow you managed to short high voltage battery power to one of the other lower voltage lines that come out of the motor (throttle, display, speed sensor, etc) that could well have blown something inside.
There's really no practical way to design for those kind of faults, making all the low voltage control circuitry tolerant of 60V would be extremely expensive, if it's possible at all. No way a fuse is gonna blow in time to avoid it.
The motor is probably fine though, it's possible high voltage made it to a hall sensor and nuked it but that's unlikely.
A fuse in the battery wouldn't necessarily save the BMS, only if it blew before anything on the BMS did.
Secure your wiring.
When you have tested the battery, it will take a charge, supply power as normal, and also supply it's rated AH, THEN you know that it is fine. Insisting it is fine just because you put a fuse on it is simply not adequate.
Following on from that, just exactly HOW do you know you even have a problem? Splice in a new wire, SECURE IT CAREFULLY to keep it from getting mangled in the chain, and then describe in some detail what happens when you connect and turn it on.
Hopefully something slightly more informationally useful than "it won't go."
Following on from that, just exactly HOW do you know you even have a problem? Splice in a new wire, SECURE IT CAREFULLY to keep it from getting mangled in the chain, and then describe in some detail what happens when you connect and turn it on.
Hopefully something slightly more informationally useful than "it won't go."
The controller should be fine if you shorted the main battery wires. Fix the wires and test.
halfeuro said:
As others have pointed out, a fuse isn't nearly fast enough to save your BMS if you short circuit the thing. A fried BMS sometimes shows normal voltage at the discharge and charge leads, but it won't work when you put a load on it.
Determine whether your battery will support a load before you proceed to something more expensive and complicated. If it won't work, replace the BMS.
If your bike still won't work after you replace the BMS, then you worry about the controller.
Isn't the electrical system of a BBS02 supposed to be isolated from the bike frame?
If that would be the case, the positive from the battery touching the frame shouldn't create any sparks.
Assume the bike frame is battery gnd, (It could be as it was used as gnd for bike lights when we still had dynamo's powering them.)
than basically, connecting battery positive to gnd is shorting the battery. If the buildin BMS board has a shunt resistor to measure the battery current, this is likely the first and only thing that will burn out.
If the bike frame isn't battery gnd, the situation is worse as you don't know how the battery voltage found a return path to it's battery gnd. It's very well possible that a low voltage wire like a hall sensor one already was in contact with the bike frame and that connecting the battery voltage to it simply burned out that device or the controller input connected to it.
So, after fixing the wire, does your display still turn on?
If it doesn't, you should check if you still have voltage going to your motor.
If I read correctly, the battery voltage is going to the display and when it's turned on, it passes that voltage to another wire so that the motor electronics wake up. Even with a defective motor or controller, you should see something on the display when you turn it on. (At least that's what I would expect.) If it has no communication with the motor controller (defective controller?), I would expect it to display an error message. If the controller still works but something went bad in the motor (like a bad hall sensor), I would expect another error to show up on the display.
It isn't normal to start with that something (not being battery gnd) is making contact with your bike frame, so you should figure out that issue first. (If it's the case)
If that would be the case, the positive from the battery touching the frame shouldn't create any sparks.
Assume the bike frame is battery gnd, (It could be as it was used as gnd for bike lights when we still had dynamo's powering them.)
than basically, connecting battery positive to gnd is shorting the battery. If the buildin BMS board has a shunt resistor to measure the battery current, this is likely the first and only thing that will burn out.
If the bike frame isn't battery gnd, the situation is worse as you don't know how the battery voltage found a return path to it's battery gnd. It's very well possible that a low voltage wire like a hall sensor one already was in contact with the bike frame and that connecting the battery voltage to it simply burned out that device or the controller input connected to it.
So, after fixing the wire, does your display still turn on?
If it doesn't, you should check if you still have voltage going to your motor.
If I read correctly, the battery voltage is going to the display and when it's turned on, it passes that voltage to another wire so that the motor electronics wake up. Even with a defective motor or controller, you should see something on the display when you turn it on. (At least that's what I would expect.) If it has no communication with the motor controller (defective controller?), I would expect it to display an error message. If the controller still works but something went bad in the motor (like a bad hall sensor), I would expect another error to show up on the display.
It isn't normal to start with that something (not being battery gnd) is making contact with your bike frame, so you should figure out that issue first. (If it's the case)
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