Auto reset circuit breakers

[bluehilux]

Are these ok?

http://www.ebay.com.au/itm/CIRCUIT-BREA ... 43b653b06b

I'm looking at using them throughout my dual battery system. 2x 40A for both power cables on my BCDC1225, 1x 30A for my dedicated fridge cable (aux battery) and 1x 50A on my cable to the rear fuse box (aux battery).

The advantage I see is that you have a momentary surge or short which corrects itself you don't loose your aux battery, fridge, etc.

Also the compact size, surface mount etc really make them a desirable way to go.

But what happens if the short is permanent, ie, cable pinched onto chassis, etc? Does the breaker stay open?

Is there a good trusted and proven brand/model that anyone would recommend?

Up front I'll feed a 6 way fuse box with blades for the spotties, etc because they're not critical and you'll notice if they're not working, but loosing the auxillary system while driving might go unnoticed for hours.

Anyone care to comment?

[10 luxxxx]

I have thought about this myself and have decided rather than risk something going wrong in a big way I will have a small led light that tells me the power to the rear of the truck is still working.

[bluehilux]

I have thought about this myself and have decided rather than risk something going wrong in a big way I will have a small led light that tells me the power to the rear of the truck is still working.

Yeah I get where you're coming from, but what are the alternatives?

I read about some one using 240v resettable circuit breakers, claiming they worked at the same amperage but went off slightly slower at 12v which was desireable to prevent accidental tripping during startup, etc.

I'm looking for some kind of compact breaker that can be surface mounted, has a screwed terminal post and preferably waterproof.

[Alby]

I have the resettable 12v breakers from Jaycar, saves mucking around with or running out of fuses


Edit: link to the type I used in 30 amp, they look like they have some better ones now
http://www.jaycar.com.au/productView.asp?ID=SF2266

[Magiver70]

I would go the manual reset ones, I have in all the dual battery installs I have done, the main issue and I've seen it happen, is if you don't pick up the fault and it auto resets it will keep tripping & restating until it gets hot & welds itself shut and you still have a fire..... With a manual one if you reset it and it trips while you are there you go looking for a fault

[bluehilux]

I have the resettable 12v breakers from Jaycar, saves mucking around with or running out of fuses


Edit: link to the type I used in 30 amp, they look like they have some better ones now
http://www.jaycar.com.au/productView.asp?ID=SF2266

I've actually got one of these on the way, but the size is a problem for me where I want to fit it all. Especially 4 of them.

It seems the caravaners forums have heaps of info on this type of thing as the old buggers seem to be right into it. They have some rip snorter blues over it sometimes, it's pretty funny.

They seem to mention "mini din breakers" a bit.

It wouldn't be bad if I could mount them all on a rail in a water proof PVC junction box with black plastic glands for the cables.

[10 luxxxx]

I use the jaycar one aswell it is a duel breaker 50 amps and have had no problems at all

[bluehilux]

I use the jaycar one aswell it is a duel breaker 50 amps and have had no problems at all

Wouldn't have a link would you?

I'm having a look and it seems like they've got hundreds of them

[2007Lux]

I have a Redarc BCDC1220 with a 30A auto reset breaker on the output wire (to the aux battery). I intend to replace the input fuse with an auto resetablel one also. The autosparky I deal with suggested it after I told him about my 1220 output fuse blowing on a trip last year. I'm no expert but it works fine thus far. I have also been wondering about the issue of a permanent short and what would happen to the auto reset breaker. Maybe I should get an old car battery from work rig up a circuit through a breaker, short it, sit back and see what happens?? Oh lastly I put a 40A resetable breaker on the wire which runs to the tub, I guess an auto reset could also be used here??

[bluehilux]

I have a Redarc BCDC1220 with a 30A auto reset breaker on the output wire (to the aux battery). I intend to replace the input fuse with an auto resetablel one also. The autosparky I deal with suggested it after I told him about my 1220 output fuse blowing on a trip last year. I'm no expert but it works fine thus far. I have also been wondering about the issue of a permanent short and what would happen to the auto reset breaker. Maybe I should get an old car battery from work rig up a circuit through a breaker, short it, sit back and see what happens?? Oh lastly I put a 40A resetable breaker on the wire which runs to the tub, I guess an auto reset could also be used here??

Actually that's not a bad idea.

The wires from the primary and to the aux batteries are short and in the engine bay, and not likely to be damaged or shorted permanently, so auto resets could be the go there.

The heavy cables to the tub from the aux will have to run via the chassis rail and would be much more likely to cop some damage or short permanently, so it's probably much safer to use manual reset breakers there.

There's too many choices and worries when you're planning this kind of stuff, drives you mad.

[2007Lux]

You can get little red covers for the breakers too which makes the job neat. I mounted both the auto reset breaker and the 40A manual ones on top of the fuse box between the two batteries. For the 40A I used the $19.95 breaker from this guy
http://www.sidewinder.com.au/page27.html
This page also shows you the red covers for the resetable ones.

[jimmi]

i have the manual reset circuit breakers (http://www.ebay.com.au/itm/100-AMP-12V- ... fa1&_uhb=1), and im changing back to fuses, this thing are very unrelible, i have 8 or so in my truck, ranging from 100-500amp, they are slow to react to a "Short circuit" doesnt stop voltage spikes as they delay on tripping. and in higher amperade application, unless they have silver contacts, tend to weld themselves shut. i thought they would have im proved since i last tryed them. the lil silver ones http://www.ebay.com.au/itm/CIRCUIT-BREA ... 43b653b06b have been tryed and tested, ford falcons have used these in the hi beam circuit since EA (1985ish) there great as long as you dont exceed the amperage, they do get hot and melt stuff. the blade fuse ones arent bad either http://www.ebay.com.au/itm/NARVA-10A-CI ... a1e&_uhb=1.

personally i would go with manual reset circuit breakers, they are there to protect the circuit, if they trip there is something wrong. with an auto reset for dual batteries it may be too late once you realise the circuit breaker has failed. i have 1st hand seen a 100amp circuit breaker set a battery on fire, and drop acid everywhere.

[Magiver70]

Have a look at repco or auto pro somewhere that sells a lot of car audio, they generally have a slim inline manual reset in various sizes to drive big stereo systems

[outbackjoe]

What's the attraction to auto reset? Not having to flick a switch? It's not a good arrangement to continue to reset onto a fault. Actually you should physically check / inspect before resetting any breaker. If the breaker is clearing a large current it will eventually fail to clear it if you repeatedly reset onto the fault.

Fuses clear a fault faster than circuit breakers but correctly specified circuit breakers will operate fast enough to protect cables and avoid fire. The circuit breaker needs to be able to interrupt the current from a dead short which may be a couple of thousand amps on a shorted lead acid battery with big cables. Generally don't use AC circuit breakers for DC unless the datasheet specifies a sufficient DC breaking capacity. AC breakers rely on the zero volt crossing of the AC waveform to quench the arc and break the current.

[bluehilux]

What's the attraction to auto reset? Not having to flick a switch? It's not a good arrangement to continue to reset onto a fault. Actually you should physically check / inspect before resetting any breaker. If the breaker is clearing a large current it will eventually fail to clear it if you repeatedly reset onto the fault.

Fuses clear a fault faster than circuit breakers but correctly specified circuit breakers will operate fast enough to protect cables and avoid fire. The circuit breaker needs to be able to interrupt the current from a dead short which may be a couple of thousand amps on a shorted lead acid battery with big cables. Generally don't use AC circuit breakers for DC unless the datasheet specifies a sufficient DC breaking capacity. AC breakers rely on the zero volt crossing of the AC waveform to quench the arc and break the current.

The attraction is the fact that you don't unwittingly loose your fridge/aux over a surge of temporary fault, but mainly just due to the small size of them and convenient terminal post.

I'd use all ANL fuses if they weren't so bloody big, I'm just strapped for space where I want to put them.

Funnily enough I just spoke to the field service manager for a very large mining auto electrical mob in Mackay, and he said the auto resets were fine and that he'd never seen one melt ever. Mind you he did mention that they come in varying qualities and he'd be wary of the ebay ones.

He said he had everything there from OEM Cat breakers to basic fuses and that if I came down he'd help me out with it (I did something for him recently).

Personally, I think those maxi blade fuses look fine but I just can't find a suitable holder. I won't use those inline holders with a wire out of each end, I need surface mount.

Mate, I read your blog extensively about this.

What breakers/fuses are you using?

And thanks all for your replies as well.

[10 luxxxx]

No link mate but this is the one I have from jaycar being in wa it was the only double breaker I could find
Works a treat.

[2007Lux]

Funnily enough I just spoke to the field service manager for a very large mining auto electrical mob in Mackay, and he said the auto resets were fine and that he'd never seen one melt ever. Mind you he did mention that they come in varying qualities and he'd be wary of the ebay ones.

He said he had everything there from OEM Cat breakers to basic fuses and that if I came down he'd help me out with it (I did something for him recently).

Personally, I think those maxi blade fuses look fine but I just can't find a suitable holder. I won't use those inline holders with a wire out of each end, I need surface mount.

Mate, I read your blog extensively about this.

What breakers/fuses are you using?

And thanks all for your replies as well.

The autosparky I consulted also fits out 4wds for the mining industry here in town so if there was an issue with using auto reset breakers it would have surfaced by now? Below is a pic of the BCDC1220 output fuse that blew whilst out camping. I never found a reason why it blew, it was suggested to me the contact was poor which resulted in a higher resistance, which = heat, which resulted in meltdown. It took me a day to realise my aux battery was going flat as the fridge was simply running off the battery and as I do not have battery monitors I failed to realise the output fuse had blown. I only diagnosed it when the ARB fridge light went yellow which told me there was a low voltage issue.

[outbackjoe]

I just use fuses, if everything is correctly sized and installed you'll almost never get a trip that is safe to reset without some sort of intervention.

I'd be very surprised if in mining an auto resetting circuit breaker was used as the sole form of protection. In other words there would be a fuse that operated for large currents, the circuit breaker would be for overload level currents which would be ok to self reset. In the event of short circuit level currents the fuse would blow and prevent constant re-closing onto the short which would eventually destroy cables and equipment.

[2007Lux]

I only use the autoreset for the BCDC output wire. The line that feeds my tub has a 40amp manual breaker on it very close to the battery, plus the two cigarette sockets in the tub have 10A manual resetable breakers on them. I also have an anderson plug for my fridge in the tub, but if the fridge shorts internally that has it's own fuse. So the way I see it the use of an auto resetable breaker in my case is to stop a load spike blowing my BCDC output fuse and thus defrosting my fridge. The chances of getting a permanent short in the small cable runs charging the aux battery under my bonnet would be IMO very low.

[bluehilux]

I only use the autoreset for the BCDC output wire. The line that feeds my tub has a 40amp manual breaker on it very close to the battery, plus the two cigarette sockets in the tub have 10A manual resetable breakers on them. I also have an anderson plug for my fridge in the tub, but if the fridge shorts internally that has it's own fuse. So the way I see it the use of an auto resetable breaker in my case is to stop a load spike blowing my BCDC output fuse and thus defrosting my fridge. The chances of getting a permanent short in the small cable runs charging the aux battery under my bonnet would be IMO very low.

Yes, that's where I'm at as well.

I certainly see Joe's point, they go off for a reason and that should be investigated.

The mines use a risk matrix (which can often lead to furious jerking off) to ascertain what the risk is and how likely it is to happen, putting it very simply.

I doubt they would use resetables as well, as it's a cardinal sin out there to reset anything without investigation.

My point is the same as 2007lux's.

The input and output of the BCDC are on short heavy wires in the engine bay that are easily inspected. The most likely cause of a trip would be a surge or spike (which I read somewhere but can't find again) which may happen when starting or the aux battery is really flat or both. As the risk of a permanent short are much less, in my mind the resetable becomes acceptable, even desirable.

On the other hand, the risk of mechanical damage and permanent shorting of the cables running down through the chassis and tub is much greater, as well as the fact that the cables from the aux battery may be carrying a much higher current (or at least running a higher rated fuse/breaker). For my peace of mind I'd need a manual reset breaker or fuse in that case, and would only want to reset/replace after I'd checked it out and was watching it while it was turned back on.

I run hydraulic hose and cables through heavy mining equipment in aggressive environments for a living. The risks can be minimized by routing things correctly, proper clipping and support, protection against rubbing, etc.

But certain places have inherent risk of damage not matter how you do it.

For me I'll think about it some more, and go down and get my spark mate to show me some options.