Over-current protection for main battery wire?

The way the civic is wired, the main battery goes straight to the starter, with a jumper from the starter over to the main fuse box. So everything except the starter is fused. I'm adding power steering and using an MR2 electric pump, and am planning to daisy chain it from the starter terminal. Playing with all of these big wires again, I wondered about over-current protection. What does the rest of the world do? I know that cars usually don't have protection in the line from the battery to the starter stock, but stock there is a 2' run thru air, where with a rear mounted battery I've got 15' thru a passenger cabin, a firewall, etc. Ideally I'd have a well sized circuit breaker about 1' downstream of the battery, but I'm not sure if that's overkill or is just adding another potential failure point.

Thoughts?

Don't Maximas and other Nissans have a main fuse in the harness to prevent excessive draw? I only hear about it in a negative way when people keep popping them trying to fix a problem. Might be a potential source of some type of fuse.

Your set-up should help prevent welding of wrenches when forgetting to remove the battery terminals and that the starter posts are always hot.

My ur-quattro nearly burnt up when a braided oil cooler line sawed through the unfused battery line from the rear-mounted battery. (Someone had misrouted the lines when replacing something?) Only good timing of my wife arriving home to the car smoking in the garage kept it from being a disaster.

Not certain what the solution is (my Fiesta routinely blows the 50a fuse it uses here) but the concern is very real.

Don't most cars use a fusible link? ie. a section of rdeuced size wire that will melt if you overdraw.

Slightly off topic - I don't know anything about electric power steering assist, but won't having it hot all the time kill your battery when the car's not running? I suppose you could run it with a relay with a key-on power trigger if that's the case.

On topic - http://www.cooperbussmann.com/6/HeavyDutyFuses.html

all of my cars run right from the battery to the starter. On my old NG900 the battery cable split in two.. with one half going to the fused stuff and the bigger cable running in a daisy from battery to starter to Alternator... no fuses

NGTD wrote: Don't most cars use a fusible link? ie. a section of rdeuced size wire that will melt if you overdraw.

Yup, that's what you need, we almost burned up our XR4 because we bypassed this when we were first working on the car...

DILYSI Dave wrote: The way the civic is wired, the main battery goes straight to the starter, with a jumper from the starter over to the main fuse box. So everything except the starter is fused. I'm adding power steering and using an MR2 electric pump, and am planning to daisy chain it from the starter terminal. Playing with all of these big wires again, I wondered about over-current protection. What does the rest of the world do? I know that cars usually don't have protection in the line from the battery to the starter stock, but stock there is a 2' run thru air, where with a rear mounted battery I've got 15' thru a passenger cabin, a firewall, etc. Ideally I'd have a well sized circuit breaker about 1' downstream of the battery, but I'm not sure if that's overkill or is just adding another potential failure point. Thoughts?

The miata's battery is in the trunk, and it doesn't have a fuse on the main line before it gets into the engine bay (granted, I don't think that's a 15' run, but just a thought...)

I've never heard of it having a fusible link in the wire, but I couldn't promise anything.

yes.. the Fiat 124 spider is the same way...

and the PO of my car, cut the wire and put this HUGE crimp in the middle of it.

A crimp that came apart when I tugged on it, I might add

DILYSI Dave wrote: Ideally I'd have a well sized circuit breaker about 1' downstream of the battery, but I'm not sure if that's overkill or is just adding another potential failure point. Thoughts?

Thoughts:

1. if it's ideal to you, put it in.
2. yes, that's what she said.
3. yes, it's adding another potential failure point.
4. what's the reliability of a breaker that is properly sized and intended for this application?
5. i'd recommend supplying the EPS through a relay. study the MR2 shop manual and do something similar.

AngryCorvair wrote: 5. i'd recommend supplying the EPS through a relay. study the MR2 shop manual and do something similar.

Planning on a starter relay for the EPS pump.

Most cars have a 100 amp fuse or fusible wire after the starter. Too have a fuse or circiut breaker in the starter cable you would need at least 200 amps or more.

I run a 150A fuse about a foot from the battery on my rear mount. I also have an 80A breaker in series with my MR2 power steering pump setup.

I ran a circuit breaker about a foot from my battery when I relocated it to the trunk in my SE-R as a precaution. Can't remember the exact current rating but I think it was this one on Amazon. It also doubled as a theft deterrent as I could push a button and open the circuit, but I rarely did as it would erase all my radio presets.

140 Amp circuit breaker acquired from local stereo shop. Looks identical to Clay's. Side benefit is a disconnect to keep my battery from dying between events.

Some starters can draw over 160 amps.