trazor said:
I maybe try to repair it as you suggest. I don't get voltage on the serial port. Can that be an indication of a major problem, not only with the mosfets?
About the overload... I didn't pull so much energy. I was using my bike with a Kelly KBS72121X with a Denzel4500 motor. Probably not more than 60 phase amps and not full duty cycle. And... about overload... aren't BMS designed to cut energy if they detect an overload?
After changing the BMS (reconfigured one 16S to 18S) my bike works flawless now, so I don't think there was a short in any place.
Thanks for your input and keep ideas coming.
Pull the mosfets, make sure there are no stray solder blobs anywhere. Then connect the BMS via batt- and the balance cables to your pack. Let's see if after a little clean-up if the logic and cell control electronics still work. If they are good, get more mosfets and consider doing a full upgrade like I've posted here.
https://endless-sphere.com/forums/viewtopic.php?f=14&t=95853&p=1403576#p1403576
Overload...yes, I was wondering about that too. The point of the P- mosfets is to shut off current flow in an over load. That didn't happen and there are reasons for that. A single mosfet with an internal short would be sufficient to keep the BMS flowing current even if the rest of them in fact shut off. That one mosfet would get quite HOT. Once you have the mosfets pulled, you can test the control logic to see if the mosfets are getting the right signal to shut off. It is possible that a mosfet gate was shorted somehow to something that held it active and caused this condition. I'd be looking closely at the board for solder blobs and other blown parts.
We can talk about testing later. Get the mosfets pulled first so you can start looking at survivability for the "brains" of the BMS. What I can tell you from personal experience with electronics is that it is common for the high current parts to die and the rest of the device is OK. I've blown all 18 mosfets in a controller and the rest of it survived. 18 new mosfets and a year later that controller is still running strong. I've seen many power components blow over the years in PSU's, controllers, DC-DC converters and other things. Replace those power components and the rest of the device is still OK. It's not guaranteed, but I'd give it 80%. I've been doing electronics repair since the mid 1980's. I've seen loads of electronic devices that let the magic smoke out and are repairable.
To me this BMS is an exploratory learning opportunity. Maybe that's not your thing? But then I am a modder and hacker of just about everything.
Getting your bike going again. That proves the problem is localized to the BMS...which is good!