Charger causing tingling sensation through bike frame

I'm 95% through a new project of mine - my battery is an 18S 24Ah Lipo pack and I've just wired a new connector to a brand new 75V Li Ion charger. Plugged the charger in and it's charging the bike fine and dandy. I go to put my bike lights on while the bike is charging and I can feel a weird tingling on the seat post. Touch the handlebar and brake handles and can feel the same sensation.

What on earth is going on? I didn't get this with my old bike which had a 14S pack. I've turned the charger off now for fear of electrocution myself - anyone know where I can start looking for the problem?

Thanks
Jon

If you're feeling tingling, it means you have a voltage across the affected part of your body. I'd say first, unplug the charger and the battery, and inspect your wiring to see if you have an obvious skinned cable or naked terminal touching something it shouldn't. If no clues, put the bike somewhere so that no conductive part of it is touching something else conductive; you want to completely avoid connecting to mains wiring or to ground. Then plug in your charger and battery, grab a multimeter and start probing things to see what's showing a voltage.

Sounds like you have two problems: a live frame and possibly a non-isolated charger.

1. Your bike electrical system should not be grounded or otherwise connected to the frame (for what should now be obvious reasons). If you installed motorcycle lights that use a frame ground and so connected your pack or DC/DC converter GND to the frame - that's the problem. Otherwise you have an inadvertent short between wiring and the frame. This could be a chafed wiring harness, a phase short to the stator core in the motor, loose solder blob in controller to the case, etc. Testing is a matter of unplugging everything and testing for continuity/resistance between connectors and the frame (e.g. the motor phase wires and frame, battery leads and frame, etc). This is a Not Good safety situation, but if it's in the motor, you will likely have put up with it since that's pretty much unrepairable but in itself not a showstopper.
   
   
2. The charger may have a short from the mains to the charge leads. Unplug the charger at both ends and test for continuity or resistance from each the (+/-) charger leads to each of the mains prongs on the plug. You should see no connection. If there is a connection, replace the charger or otherwise remedy the issue - it's a deathtrap.

Now that you mention it, the voltmeter that I have came with a large shunt that I've placed quite close to the controller and could be 'grounding' against the frame. Is this the sort of thing that can cause this problem?

jonnybump said:

Now that you mention it, the voltmeter that I have came with a large shunt that I've placed quite close to the controller and could be 'grounding' against the frame. Is this the sort of thing that can cause this problem?

Click to expand...

Yes.