[firstgear]

I am relocating the battery in one of the cars and in the process I want to add some safety features, specifically a fuse and a battery disconnect switch.

I am looking for confirmation of what I am planning on doing is the correct method.

First, the battery fuse, I am looking at an inline fuse to the battery positioned very close and inserted in the positive circuit. The fuse size is 100 amps.

Second, the battery disconnect is the type that is put on race cars and I am planning on putting that in the negative lead side of the battery.

Is the above correct?

Thanks in advance....

[EOD Guy]

My advice...... put a 70 amp maxi-fuse next to the battery and feed everything from there.... except the starter, I'd hook that the normal way....... cable straight from the pos post on the battery to the starter lug. I have my disconnects hooked to the neg cable...... I use the one from Advanced Auto or Auto Zone..... they have a large red "L" key etc.... works really well and runs about 18 bucks.

[Oldguy48]

You don't state what vehicle you are referring to, but I think it's likely that your starter will require in excess of 100 amperes to crank the engine over, so you might want to research that a bit more before buying components. And if 100 amperes is sufficient for your vehicle, there are 100 ampere circuit breakers available (I bought mine from AutoZone to install in my alternator circuit) that are resettable in the event they trip on overcurrent. No fuse replacement required, just press the reset button.
The disconnect switch can certainly be installed on the negative side of the battery. Placing it in either the positive or negative side disconnects the battery completely from the vehicle. As long as the battery circuit is broken (switched open) somewhere, the electrical system is de-energized.
As far as the disconnect switch is concerned, unless you are sure of what you want to use, take a look at the disconnect switches from the marine supply vendors. I purchased one for my 1948 Plymouth, and it's rated for in excess of 200 amperes and has been working great for me.

[firstgear]

Thanks EOD Guy. Very helpful. From the maxi fuse to the fuse block, what gage wire would be appropriate?

I am putting the battery under the car (Model A with SBC). Since the battery is under the car, do you know a source for a waterproof fuse holder that could be located next to the battery?

[firstgear]

Originally Posted by Oldguy48

You don't state what vehicle you are referring to, but I think it's likely that your starter will require in excess of 100 amperes to crank the engine over, so you might want to research that a bit more before buying components. And if 100 amperes is sufficient for your vehicle, there are 100 ampere circuit breakers available (I bought mine from AutoZone to install in my alternator circuit) that are resettable in the event they trip on overcurrent. No fuse replacement required, just press the reset button.
The disconnect switch can certainly be installed on the negative side of the battery. Placing it in either the positive or negative side disconnects the battery completely from the vehicle. As long as the battery circuit is broken (switched open) somewhere, the electrical system is de-energized.
As far as the disconnect switch is concerned, unless you are sure of what you want to use, take a look at the disconnect switches from the marine supply vendors. I purchased one for my 1948 Plymouth, and it's rated for in excess of 200 amperes and has been working great for me.

I bought a Summit Racing disconnect switch rated at 250 amps. It is waterproof.

[firstgear]

For about 15 feet of length, it looks like I need a 4 gage wire allowing a 3% drop. Am I off on that? The distance might be 10 feet, but that still calls for a 6 gage wire, all of the above at 70 amps.

[firstgear]

Correction on the wire size up to 10 feet and 70 amps, 8 gage is ok.

[malc]

Some tips on battery relocation, remote stater solenoid and Trunk Mount battery helper kit.

"The starter motor cable is the only electrical circuit that cannot be protected by a fuse, circuit breaker, Fusible Link, or other short circuit protection. (Because starters can draw all the current that a battery can put out, so the battery cannot put out enough power to “trip” a protective device with high enough capacity for starter motors. All other circuits can be protected, and Fusible Link wires are best for the heavy-duty circuits.)

With our START’M UP system, the cable between the START’M UP solenoid and the starter is electrically “dead,” except for during engine cranking."

[EOD Guy]

The 8 gauge will work to power everything else, but the cable for the starter, I'd use "OO" for a 15 foot run. I have used some high end "OO" jumper cables with the ends cut off to run batteries in the trunk, it makes for a nice neat install and you have the ground and the pos connections right at the starter etc.... some have used ford starting solenoids for relocation but IMO you still have to run heavy cable to the starter and I don't see the benefit.

[sparkchaser]

Just a note: If you decide to run your car at the drags, the rules require the cutoff to be on the positive side.

[ogre]

check out madelectrical.com, it shows a safe way to remote mount a battery
he uses a solenoid in the battery cable and states that the battery cable is the only wire you cannot fuse
on a cold morning it take everything the battery offers to start a cold car.

[malc]

Originally Posted by ogre

check out madelectrical.com, it shows a safe way to remote mount a battery
he uses a solenoid in the battery cable and states that the battery cable is the only wire you cannot fuse
on a cold morning it take everything the battery offers to start a cold car.

Check out post 8.

"some have used ford starting solenoids for relocation but IMO you still have to run heavy cable to the starter and I don't see the benefit."

The benefit is not toasting your car.

[EOD Guy]

IMO a direct short is a direct short, if you put a relay in the loop....it's still a direct short.......aaahhhhhh your point is that the line is dead until you turn the key and energize the relay.

Well mine setup isn't, that is unless I turn the battery disconnect off...... mentioned by the OP in his initial post, he was going to install one.

So no I still don't see the benefit, maybe in your setup it is, but before you go blasting someone, uderstand thier point of view

[malc]

Did´nt blast you at all.

[ogre]

Originally Posted by malc

Check out post 8.

missed that.
madelectrical has some good stuff on his site.

the reason you run the remote solenoid is so that you don't have a 15 foot un-fused wire as a potential short.
if it ever shorted out, when you turn the key it would short; whereas you would notice a problem and release the key and short-no-more