Apparently some vehicles used to use "positive ground". So basically the POSITIVE of the battery was connected to the chassis...
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@OpenComputeDesign nothing inherently wrong with that, just depends on your components.
Consumer microwave ovens do the same thing actually.
@matt True. Sucks when you have to connect something with a negative ground, though. Especially when you don't know about it, and go to hook it to the battery, when... TZZAP!!! Didn't help that it was a big 24v system. 24v at over 1000A makes a hell of a spark