Good call on the fuses, Monte.
ABYC calls for current regulation devices within seven inches of the battery. I've been using some solid fuse blocks now available at West Marine directly on a tight mounting directly on the battery. This allows heat built up in the wires and fuse body to sink to the 170Ah lead on the other end of the brass terminal. A remote breaker or fuse must consider cooling to ensure integrity. The Blue Sea disconnect I'm using is a good example. It's rated for 250a continuous*, 600a peak*. In the fine print is the phrase "when connected to 2/0 cable". (Anybody using two-ought?) That's for the heat dissipation from the relatively small copper contact patch. Copper, by the way, can conduct 6,000 amps per mm^2 before vaporization. The point of the wiper inside the Blue Sea Marine UL listed disconnect isn't much bigger. No worries, just make sure it keeps cool during operation.
Breakers with very large ratings can be hard to find, however, especially ones rated for the marine environment. Breakers might also require some occasional cycling to ensure contact integrity. The actual contact point within is about the same as the disconnect. The disconnect is self-cleaning during operation, as would be the breakers when switched without a load.
Breaking the power to the contactor may or may not work. If a controller is acting weird, first thing the user will do is cycle the power. If the controller is fused solid, the relay will open reliably, but weld closed upon re-energizing, which comes usually comes just seconds after a safe shut-down. I've often had to whack contactors to free them, even if it's just a few cycles with an open pre-charge resistor.
It may be possible to parallel breakers using copper buss bars connected in a first-in, last-out power flow.
Any comments anyone?
Arby
----- Original Message ----
From: Tom Regan <boat_works@yahoo.
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> As a final caution, I would never recommend using fuses on an electric
> vehicle of properly-rated circuit breakers are available. Nothing
> worse than being caught out with a dead motor and no fuse.
>
> Monte
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> This disconnect would be in addition to the keyswitch actuated battery
> bank contactor and typical fusing.
> Any thoughts?
> -Tom
>
>
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