I relocated my battery to the smugglers box in my 68 pro street elcamino and would like to install a mega-fuse for protection. I have dual elec. fans, MSD, electric vac. pump for my brakes, starter, electric fuel pump, Hella lights, one wire 100amp alternator plus all normal road lights. What size fuse should I use for protection without having nuisance blown fuses?
Thanks Dave

If you are talking about installing a fuse in the main battery cable from the battery to the starter it must be big enough to carry starting load. Check starter current draw for your engine. You may have trouble finding a fuse with enough capacity for starting.

If you are not talking about the main battery cable, normally each item is fused separately according to amount of draw for that item.

Fusible link is what you should have on the branch wire from the battery.

If you have the battery in the trunk I strongly suggest that the starter solenoid be put in the trunk too.

You can't fuse the main cable to the starter; way too much current and way too much voltage drop across the fuse.

Ron

I wanted to protect the battery wires at the shut off switch since it's mounted in the bumper. It looks like it would be easily shorted in a accident. Any suggestions ?
Thanks Dave

The new Escalade has a large fuse on the firewall for all the battery power.This is a 175amp mega fuse which would be plenty for your app.Mega fuse power from the battery to the front power distribution.

The new Escalade has a large fuse on the firewall for all the battery power.This is a 175amp mega fuse which would be plenty for your app.Mega fuse power from the battery to the front power distribution.


From a safety perspective, if you use a meagafuse at 175A with too small a wire you could still start a fire in an accidental short (like a side collision). That is a really big fuse.

Ron

I relocated my battery to the smugglers box in my 68 pro street elcamino and would like to install a mega-fuse for protection. I have dual elec. fans, MSD, electric vac. pump for my brakes, starter, electric fuel pump, Hella lights, one wire 100amp alternator plus all normal road lights. What size fuse should I use for protection without having nuisance blown fuses?

I wanted to protect the battery wires at the shut off switch since it's mounted in the bumper. It looks like it would be easily shorted in a accident. Any suggestions ?
Thanks Dave


You always want to size the fuse by wire size. A person could wire an inline 100A fuse onto an 18 gauge wire but the wire and it's insulation would melt off and the wire finally melt apart before the fuse would blow.

It would be nice if there could be just one fuse or protection device for all of the different gauge wiring in a car but it just can't be done.

I like fusing things seperately. This adds more wire and wiring, connections, possibility of problems from not doing it properly, extra costs from fuses and fuse holders, and so on but it makes it so nice to where if things are labeled and a fuse does blow you know it just powers this one circuit or in some cases makes the troubleshooting faster. Look at how many fuses the new cars have compared to the older models. Granted there are more electronics in them but some vehicles have a dedicated fuse just for the dome light and it is not tied into other things like the glove box light, cigarette lighter socket, and so on like the older cars.

How I like to wire vehicles is to run the proper sized wire for the circuit and then fuse or protect this wire from where it is getting power from. There are glass style fuses (small, medium, and large sized), plastic atc style fuses (big and little), ANL style fuses, fusible links and others.

On vehicles with a battery in the trunk, smugglers box, or under the rear seat I normally add ANL style fuses. Most of the time I'm running 1/0 wire from the battery sometimes through master on/off switches or big 200A relays and then up to the engines starter. On these I put in a 300A ANL fuse right off of the battery positive wire. If I then need to wire up an MSD box (like a 6AL box) I run an 8 or 10 gauge wire off of the battery or off of the main starter solenoid post but run it through a 30A fuse. If I'm adding an electric fan that draws 10A I might run it on a 12 gauge wire.

One thing to think about is a lot of people forget about the grounds. If you are supplying something with power on a 4 gauge wire, run a 4 gauge ground. If you have a bunch of things grounded to the body of the car, tie the body of the car with the proper sized (or even oversized wire) back to the engine block and battery.

If you design the system properly and wire it so, then you should not have nuisance blown fuses. Fuses and protection devices are used for a reason and there is normally a reason why they blow.

Jim

Thanks for all of your suggestions. But I decided to put the battery back up front ,just a short wire to the starter and a fuseable wire to the radiator support. Got rid of the shut off switch and about 6lb's of wire. Thanks again Dave