I have relocated the main battery to the rear of the car. I was wondering if anyone knew what size breaker one would use to protect the power line running up to the engine? I don't want it to some how ground out and cause a fire. Does anyone know what size it should be? Any thoughts on the matter? I have been running too long with out one.

 

I've never seen one used, just a cut off switch. The starter can easily draw a couple hundred amps. Doesn't mean they don't make them, maybe for a golf cart or fork lift.

 

Well the purpose of a fuse/circuit breaker ect is to protect the wires not the actual stuff there wired to. So what im trying to say is if you were going to get a fuse or a circuit breaker you would need to select it based on the gauge wire you used.

 

I am just trying to protect against a short circuit fire. I used welders wire. I think it is 0/1 or something like that. Its about twice as thick as factory battery cable. Any idea what breaker that might use?

 

IDK wiring stuff--
Would the way to find out be :

Add all accesseries power used
Add this to cranking power used
Check alternator for max amps safely usable

Then that would be a starting point to try breakers??
Are you using 2 batts? I see you said "...main battery..."

 

actually I am. I have a small one as a "booster" battery up front and a regular size one in the back. I have the small one isolated via a relay that I can turn on in hot traffic (electric fan) or when my engine gets really hot and needs a boost I can flip that one on and get some extra juice.

I don't know the cranking power used so I am at a bit of a loss. I guess I could try something like a 120amp fuse or something inline and see what happens. I just don't want it to be able to sit and arc and start welding stuff and cause a fire if it ever did short out somewhere. The small battery is isolated so I am not so worried about that one.

 

 

Well without knowing truely what gauge it actually is i cant make a recomendation as to fuse or breaker size. I dont want to say one thing and hear your car burny up because it was sized incorrectly ya know what i mean. Although i will say that theres alot of people commenting about heavy draws like the starter but thats not really what you would base your fuse or breaker on. This is because a lot of things especially motors have a higher than normal draw on start up. However it only does this for a short period of time which is ok. For example you only supposed to crank a starter for 30 seconds max befor letting it cool or else it will burn up. This is because the current draw exceeds the motors maximum CONTINUOUS rating although it is fine for maximum intermittent. Same thing with even wires. A wire thats rated for 10 amps may do just fine passing 100 amps but for maybe no longer than 1 tenth of a second. Because of this fuses are rated for how quickly they will react. So again a slow blow fuse rated for 10 amps wont be blown by a 20 amp load if its duration is short. So not only do you need to get a fuse thats rated for your gauge wire but also something that reacts slowly to account for starting currents.

 

Thanks for the info. I guess I will try like a 75 amp and see if it holds it.