Resetable Circuit Breakers

Marty

What type of circuit breaker is it - the really small ones that only have two studs coming out of them for the connections may be a concern if they are the only protection for a battery that can put 1500 amps into a short circuit.

The arc from these high currents can WELD THE CONTACTS SHUT on the first opening.

With high-current supplies, you have to consider not only the holding current (how much will it carry before it opens) but also the Rupturing Capacity (the maximum current it can interrupt AFTER it has opened).

This arcing of opening contacts in DC becomes more serious above 24 volts and that's why we don't see too many 42 volt electrics cars, despite the excitement about them 3 years ago.

I am getting the gear I need to actually test this out.

HI MARTYB, YES IT WILL TRIP & RESET, DEPENDING ON HOW LONG BEFORE U NOTICE THE PROBLEM IT WILL JUST CONTINUE TO DO SO, ALTHOUGH IT WOULD EVENTUALLY FAIL. I CAME ACCROSS THIS PROBLEM ONCE WHERE THE WIRING BURNT ACROSS THE EXHAUST BETWEEN MAIN BATT & AUX BATT,THE CUTOMER COMPLAINED OF A TING TING NOISE COMING FROM UNDER YHE BONNET, AFTER SOME INVESTIGATION FOND TO BE THE CIRCUIT BREAKER TRIPING. HE SAID IT HADE BEEN DOING FOR A FEW DAYS. U SHOULD IDEALY BE USING FUSABLE LINK WIRE OR A HEAVY DUTY FUSE & HOLDER. IF U RUN DOWN THE AUX BATT THE CIRCUIT BREAKER WILL ALSO TRIP ON & OFF WHEN IT IS BEING RECHARGED BY THE VEHICLE SYSTEM, BECAUSE OF THE HIGH AMPERAGE BEING PUMPED INTO IT.

I prefer to use fusible links for short circuit protection because of the issues mentioned above. Most vehicle manufacturers think the same way.

I'm with Mike and Phil on this one.
Use Phil's suggestion of the fusible links, I use them too for battery whole current protection. One at each end and if you're concerned carry a couple of spares.

Geoff.

Thanks for asking this question as I had the same query.

I used circuit breakers mainly because I wanted the terminal post for the way I wired my accessories. I will keep a close eye on them for the reasons mentioned above.

Cheers
Spinifex

Thanks for all the replies, interesting to hear they will keep on tripping & resetting for days. I thought the arcing would have burnt their contacts out.

from Marty.

I have just wired up my car with a heavy duty hot wire to the van. I put a manual resettable circuit breaker (120 Amp) in so if it does short, I can reset it manually. I also means that I can use it as an isolator when not towing my van. I leave it switched off most of the time so there is no current running to my hot wire (175 Amp Anderson Plug) and only switch it on when van is attached. If I was switching on and off regularly I would add an isolator but it's not necessary in this case.

Maybe good idea to use both circuit breaker and fusible link (of a lesser amperage), say 20amp fue and 30amp circuit breaker?