dukie564

anyone have opinions on DC circuit breakers vs fuses?

Upgrading my cables and alternator, thinking about a circuit breaker instead of a main ANL fuse. 150A is what i need.

http://www.delcity.net/store/Hi-Amp-...able)/p_193073


I don't see any cons of using a circuit breaker other than cost, which isn't much more than an ANL block and fuse anyways...

xj_maniac_newb

Never heard of them, but sounds pretty neat. Would be alot more convinient should you ever get stuck in the wild without a spare fuse.

dukie564

that's part of the bonus - ANL fuses are cheap so carrying a spare isn't a big deal, until I lose the spare...or I use both of them...in which case i'm screwed.

But i guess the same applies to the stock fusible link so...


The only thing i'd be worried about is the circuit breaker not doing it's job when it's supposed to. I don't know whether that's a valid concern or not...

xj_maniac_newb

I'm sure it'd do its job well as long as its a good brand. And i'd imagine having a breaker instead of a fuse would be more convenient when trying to find a short.

dukie564

doubles as a battery disconnect also

DieselD

If you don't mind me asking, where would this go in the system?

Between battery and alt? Why have a fuse/breaker there?

dukie564

Stock configuration is with the alternator lead running into a buss bar in the bottom of the PDC, and protected by 2 MAXI50 (or MAXI60) fuses to isolate it from the rest of the system. This is not sufficient for the higher wattage alternator (136A).

My plan is to run the alternator straight to the battery + post, with the new 150A fuse/breaker between the alternator and battery to protect the system. Electrically speaking it's the same thing.

DieselD

Ah, thank you.

Good info. I have a 136a in my 91, all wiring was left stock. I need to fix that. (There's a lot more on the to-do list for that one)

dukie564

ooh yea you should. If that alternator ever reaches full output you stand a good chance of blowing your fusible link

DieselD

Oh its on the list (a long list), was just gonna do wires and new battery (doesn't have one now) but I never see any mention of isolating the alt+batt when upgrading to a higher output alt.

I also kind of thought that the "regulator" (as in internally regulated alt) did, take care of extra amperage...

I don't know squat about electric (can you tell) its always nice to learn.

dukie564

also...


why the **** is it so hard to find solid brass marine battery terminals!

dukie564

Well the PCM regulates the alternator yes. The alternator output is proportional to the voltage applied to the field coils. This means if the field coils ever see the full battery voltage (due to a short or PCM regulator failure for example), the output voltage would spike and amps could exceed several hundred amperes, which is enough to fry the entire computer/electrical system. Enter the purpose for the fuse/breaker.

XJDAD

Since it does appear to be electrically the same yet it allows for the higher op alternator I would say go for it. Then let us know how it goes.

Oh, and I noticed the Del City web link. One of my faves when it comes to electric supplies.

xj_maniac_newb

I'm pretty sure Advanced auto keeps them in stock, thats where i got mine.

dukie564

i haven't seen the nice thick marine style ones there?