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I'm aware in the automotive world the chassis of the vehicle is used as the return path to the battery negative however I am building an electric-powered cart running on 48V lithium batteries. The batteries come pre-built within a plastic enclosure with an Anderson connector.

The batteries will be fitted on the cart which consists of a metal frame sheet metal body. I do not intend for the frame to carry current.

My reasons for not are: By not connecting the frame to the negative, a short circuit would require both pos and neg to come into contact with the frame. A user should not receive a shock should they come into contact with a fault arising in an energized frame/body/accessory/cable as there is no path back to negative.

Is there a benefit in this application to connecting the frame to the battery negative?

Matt Roberts
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At 48 V, shock hazard is minimal.

Your batteries can probably deliver an embarrassingly large current in the event of a short circuit. Having the battery and the rest of the drive electronics isolated from the chassis means that you would need two faults to chassis rather than one to get a short.

You may find that an isolated chassis can enhance some frequencies of EMI coming from the electronics. If you are building a hobby one-off, you'll probably get away with this. If you're designing carts for a production run, then get this aspect checked out with a test house before you burn too much development money.

Neil_UK
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