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Tech => Home Brew => Topic started by: Gregski on July 26, 2011, 01:26:10 PM

Title: Does the Controller Have to be Isolated!
Post by: Gregski on July 26, 2011, 01:26:10 PM

I am in the home stretch of completing my motorcycle conversion.  When mounting the aluminum controller to my metal battery tray I got to thinking... does it need to be isolated somehow from the frame of the bike?  Using rubber or wood or something so that it does not short out...  I am new at this so please be gentle.

Title: Re: Does the Controller Have to be Isolated!
Post by: Bogan on July 26, 2011, 01:35:35 PM

I would not expect it to need isolation, my alltrax doesn't.

Good to hear you're on the home stretch, let us know how it turns out!

Title: Re: Does the Controller Have to be Isolated!
Post by: frodus on July 26, 2011, 09:32:07 PM

it depends.

Can you test continuity between B- and the case? B+ and the case?

If you do, putting the controller direct to the metal frame essentially makes the whole frame ground, and if you work on the bike, do not touch any high voltage connections while leaning against the frame.

It's the same reason we keep our 12V isolated, so we don't get shocked.

It boils down to "are you ok with that risk?"

Title: Re: Does the Controller Have to be Isolated!
Post by: Bogan on July 27, 2011, 03:45:38 AM

We do? oops! I have a big earth lead going from the battery to the frame, and the 12V earth is a frame earth too. Only thing I've noticed is stuff on the 12V side interferes with each other, but that is more because of the DC-DC converter output voltage fluctuation.

Shock from a 48V system will tingle, but unless you lick the terminals I don't see any real damage occurring. It took me while to figure out I was even getting shocked from my 36V system (felt more like rough edges on the frame).