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[rgutt]

Does anyone have firsthand knowledge as to whether the BMS on the Gen2 bikes will actually shut down the BMS for an isolation fault? I ask because I had a sensor problem I tracked to voltage being injected into the frame that was being picked up by an analog sensor I had mounted on the brakes. I tracked that voltage to the system the BMS uses to detect battery isolation in the first place. I can filter out the noise simply by connecting battery negative to the bike's frame, but that's typically a no-no for EVs (though I am much less concerned about it on a 100V system, and I can always put a small fuse in the wire to address the astronomically low possibility of an eventual short from the positive wire).

Anyway, I let the bike sit on the charger as well as powered for a while to see if the BMS would ever shut it down with what should be detected as a direct short between battery negative and frame. Other than the flicking warning lights, it does nothing. My only fear is that the BMS eventually opens the contactor whilst at speed, which above about 45 mph, the back EMF would be enough to blow the motor controller.

So, has anyone ever firsthand had a Gen2 bike shut down for a battery isolation fault?

[TheRan]

I don't know if that relevant to what you're asking but early in my ownership after I'd wash my bike with a hose the next day I'd get the bike shutting down with a chassis isolation fault. Well shutting down probably isn't completely accurate because almost everything would function as normal, it just wouldn't put any power to the motor.

[rgutt]

That is relevant. Thanks. Do you recall if the contactor was closed?

[TheRan]

Yeah because everything else was working, I still had lights and the dash was working. Because of this I wasn't actually aware of what the exact cause was at the time, it could have been something like a faulty throttle, but I checked the error code and transferred the logs and it told me it was the isolation fault.

[rgutt]

The lights and dash don't get power through the main contactor, so that isn't indicative that it is closed. Generally, the only way you'd know is if you heard the click within about 10 seconds after turning the key to on.

[TheRan]

Is there a secondary route then for power to come from the battery? I thought it was just the one contactor. It's a gen 2 bike, and I thought that's why the gen 3 added the 12v battery so they could then have constant power to stuff like the cellular connection.

[rgutt]

The main contactor is just for the high current feed to the motor controller. There are several high voltage feeds that leave the battery by alternate routes for the DC-DC converter and MBB just off the top of my head.

As for the 12V battery on the Gen3 bikes, that was likely just to make their lives easier. The last rendition of the Gen2 stuff included a smaller always powered 12-volt module in addition to the main DC-DC converter, probably to address the OBD port requirements of a constant 12-volt source in Europe.

[TheRan]

I see, in that case my experience isn't much help. I though I had a thread where I posted the logs but I couldn't find it. Unfortunately (or perhaps fortunately) it never happened at high speed to tell whether regen cut out, I think it was usually when accelerating hard uphill.

[TheRan]

On the way home from work tonight I had a BMS isolation fault, didn't notice anything abnormal with the bike. If it wasn't for the red triangle flashing away I wouldn't have known.

[ESokoloff]

In my case codes 20, 28, & 29 produced rapidly flashing red triangle & green run led’s but the bike kept running.
This was January 23 during rain & I found that the steering head had pinched the keyed disable switch (ignition if ICE) wire insulation & this provided a path to the chassis.
The fix was to find & fix compromised insulation.