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    circuit breaker

    I am using your 6ah, 52v batteries set up in parallel. They fed through a Luna switch to a Tangent Motors drive. A motor controller failure resulted in a dead short, and not surprisingly, the Magic Smoke came out of the Luna Switch after a short time. I am actually glad the switch failed and the short could have caused other serious damage. My question is: has anyone found a suitable circuit breaker 60v, 150a that has a suitable profile of releasing for ebike purposes? I would like to avoid the electronic spars between my legs event again (though some would ask if that is a bug or a feature!).

    #2
    DC breakers are available, electric cars use them, but I have not been able to find anything suitable for an ebike, still looking.

    AC breakers and fuses will not work reliably with DC voltages; they often carry a 12VDC/250VAC rating, of no DC rating at all.

    I have heard that "contactors" may be able to do part of the fusing function, as they are available for higher DC voltages.

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      #3
      There are plenty of fuses that will work and I'd look there - remember that a fuse should be rated no more than 68% of the steady-state current (they "age" at greater currents)...

      Breakers suck. Compared to fuses they are expensive, bulky, temperature sensitive and verrrrrrrrrrrrrrry........ sssssssllllllllllooooooowwwwww...... Pretty much best for dead shorts (vs. overloads)

      Comment


      • tklop
        tklop commented
        Editing a comment
        I've thought about this option too, and I appreciate your comment, AZguy.

        For short-circuit protection, I was still mulling over the circuit-breaker idea. Maybe, just
        maybe.. But now I think maybe not!

        DC circuit breakers are slow. If something goes pear-shaped, I'm afraid they'll be too slow to keep from "letting the smoke out" of expensive components.

        When considering a couple of circuit-breakers suitable for 48VDC, I read on their product page's PDF's that their painfully slow-to-trip characteristic was built-in there intentionally; as they're designed for use in circuits feeding large power-inverters--which apparently pull a surge of high-current when first connected. So, if the versions available on the market today are made that way on purpose, perhaps faster-tripping versions will eventually also come along at some future date. Who knows?

        Using fuses means carrying spares, and it can seem old-fashioned; but I think AZguy is right when he says fuses are the way to go. They're usually not expensive, the variety of fuses is almost endless, and nearly every conceivable combination of volts / amps / trip-rates can be found.

        All the best!

        Tklop
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