Correct way to wire battery and cut off switch

Looking for some help on wiring up my car. Putting battery in trunk with kill switch. One wire altenator Msd ETC.

Run the positive to the master cutoff switch.

Make sure you use around a 200 amp disconnect switch if you are using it for everything. Some are rated like 20 or 30 amps and they fail.

Alternator wire goes to battery otherwise car keeps running when disconnect switch is shut off.

This one would be the minimum I would use.......

http://www.summitracing.com/int/parts/mor-74101/overview/

Make sure you run large enough wire from the alt to
the battery based on the size of the alt and the
length you are running.. and yes it gets mounted on
the battery side of the shut master switch

hindsight, being what it is, I wish I would have used one of those "push/pull" levers and mounted the switch in the truck instead of putting a hole in the back panel of the car.

On the race car I did mount the switch inside with
the long lever but on the Rampage its mounted on the
bumper.. I dont like drilling holes in the sheet metal
unless its a MUST... you can see it on the right
side of the bumper
EDIT
A tip if you mount the switch with the arm on it..
set it up so you PULL the arm to turn it on.. if you
do it the other way(push for on) you can shut it off
IF the car launches hard.. just the weight of the arm
can turn it off

That's what I used. Flaming river makes a nice one. Mine is located just under the bumper and batt. charge plugs

Here's one way of doing it. This eliminates a hot wire running all the way to the front of the car when the disconnect switch is off.

One thing I did on the alt hot line was to put a
100 amp fuse at both ends of that lead.. just in
case it were to short out some how.. with both ends
fused if it shorted out anywhere on the wire it would
blow one of the fuses.. my alt is a 85 amp Denso

How about a 4 terminal switch like the one Speedway sells?

http://www.speedwaymotors.com/Four-Post-Battery-Disconnect-Switch,6967.html


I'm doing some re-wiring on the Savoy and I'm looking at this switch to replace the basic Moroso 2 post unit.

Gus

That switch works well.. just use the field wire on
the small terminals

Agree - I did the same.

Gus. I've also done that before. Since your going to run the field wire to the rear and back, you might want to up the wire gauge a bit. Another trick is to get rid of the push on connectors, modify the tabs for small nuts & bolts and use eyelet connectors for the alternator. The factory push on connectors seem OK but I'm still looking for aftermarket connectors that don't spread the first time you push them on.

Smart! Mines only fused on one end. Gotta change it.

Fused mine also....cheap insurance.

Don't forget to covert the stock Mopar amp gauge to a voltmeter, make sure it is activated off the ignition switch when running so it doesn't drain the battery when not running

A nice way to wire the 1 ga. starter is to use a rear solenoid so the big cable is only live when cranking! And when using a disconnect, just put it between the solenoid & battery (+).

http://www.madelectrical.com/catalog/tm-1.shtml

I have a continues duty relay on mine mounted to the firewall. Its triggers from my ignition switch but its wires run through my 4 post disconnect. Works great.

I also did the starter solenoid in the trunk. I used a Jeep solenoid that works with the stock neutral safety switch.

I'm running a Denso Toyota alternator so I have to determine what wire I'm going to run back to the switch

Gus

It really doesnt matter.. one goes to key on side
for power and the other is the sense/exciter .. if
you have a third wire that is for the dash bulb if
it quits working

Yeah I was going to go to the key on wire because I know it will stop charging as soon as that wire looses voltage. I just have to figure out where the switch is going to be in the circuit.
Gus

I used a 4 terminal switch and wired the MSD power wire to the switched side of the terminal. Kills the ignition immediately.

I was wondering if anyone ever wired one that way. What gauge wire did you use? 8-10

Thanks

Gus

That would probably pass tech almost anywhere but if I understand what you described correctly, what do you do about other critical components, like an electric fuel pump if you have one. If you need everything shut off in an emergency, especially if you can't, you might have a real bad situation on your hands.

I believe you are correct.. in the rule book it states it
should kill ALL power... but its been a while since I've
read that section

Engine shuts off alternator doesn't charge, fuel pump shuts off when when voltage is not present to energize the relay

Gus

I see what you're saying Gus and 70hemiGTX. You're right. My mistake. As long as the battery is by itself on one large terminal and everything else is on the other large terminal, it would do exactly that.

I too have wired the last few buddies cars this way (1st contact pos. battery, MSD small red wire on 2nd contacts of switch). This allows you to

A) Have short length altenator wire of smaller size (weight)

B)All battey power is off up front when the disconnect is off

C)You have no problems with engine run on after switch is thrown caused by altenator of any style

This is what the rule book states:

An electrical power cutoff switch (one only) must be installed on the rearmost part of each vehicle and be easily accessible from outside the car body. This cutoff switch must be connected to the positive side of the electrical system and must stop all electrical functions including magneto ignition. The off position must be clearly indicated with the word “OFF.” If switch is “push/pull” type, “push” must be the action for shutting off the electrical system, “pull” to turn it on. Any rods or cables used to activate the switch must be minimum 1/8-inch diameter. Plastic or keyed switches prohibited. Switches and/or controls must be located behind rear wheels on rear-engine dragsters.

Contrary to what most people think, the main battery cable from e the starter to the battery does NOT need to be disconnected through the disconnect switch as long as all electrical functions shut off (engine, fuel pump, water pump, etc.). I verified this with NHRA tech some years ago. This is also how you get away with a lower rated switch.

There is a lot of ways to wire this, but if the switch doesn't cut alternator charge off, that wire can keep the system charged as the engine slows down. If you have ever seen a throttle stick and the battery switch is turned off, its a LONG time before that engine stops. This can be several seconds of a fuel pump running pumping fuel someplace you don't want it to go. Please consider this important safety factor.

My suggestion is leave the battery in the engine compartment, and save yourself a ton of time and money. I would like to see if any actual testing has been done to prove if any actual performance is gained with a battery in the trunk. I know the car will gain weight with all the extra heavy wire. Your wallet will be lighter with all the parts you need to buy to do it correctly and safely. I won't ever do it again, lot of work for very little if any gain in my opinion. The engine compartment looks nicer, thats about it. I have a excellent wiring diagram, but I can't post it here, since I have it saved to my computer, not on a website. I hate the way Moparts is now, can't save good forum threads (lost tons of great ones), and impossible to add photos now. I can email you a version if you want it.