battmann

iTrader: (9)

i'm trying to plan out all the items i need to install under the car (brake lines, fuel lines, battery cables, etc...) and have some questions regarding moving the battery to the hatch. i have an LQ4 engine and will be using f-body accessories and PCM / wiring. i know i need a shut off switch and sealed box. i found the diagram below on LS1tech for wiring the battery in the hatch. here are my questions:

1. i have read that some alternators have an exciter wire that should get connected to a dash light? how can i tell if this is this something i have to wire on my swap? i'm planning on installing all autometer gauges so if this wire is required, where should i run it to?
2. should i be concerned with cutting power to the PCM with the battery shut off switch? is there a way to keep power to the PCM to not loose the stored information or is everything in the PCM read only?

sorry if these questions are basic / stupid. building an engine is easy, but i'm having a hard time understanding all the wiring involved in this swap.

coolmarocrzy

iTrader: (2)

I am using auto meter gauges and ran one small signal wire coming from the factory plug in the alternator. It is run directly to my gauge.

My battery is In a box with a shut off on the passenger side where the spare tire was. I would not be concerned with disconnecting power to the computer. You are only going to use the shut off when changing the battery or a drag strip emergency situation right? The ecu may have a re learn period if you use the shut off once the car is started again and any pending codes may get cleared. Think I've read of people running a fused or relayed direct power wire to the ecu bypassing the shut off but I didn't wire mine that way. I don't use my shut off very often. Are you planning to?

Tibo

iTrader: (15)

Don't worry about disconnecting power from the pcm, it will quickly relearn where it needs to be. The exciter wire should just be the +12V switched power wire that tells the alternator when to energize. Without that wire your alternator will not charge.

Do not fuse the ground. Don't do it. Fuse the positive wire within 18" of the battery. On all but ultra high powered car stereo systems or multiple battery systems you should only fuse the positive wire. You can do 2/0 positive wire-fuse-2/0-cut off switch-split to two wires.

If you are using a 1/0 wire I would make sure that is a fine strand COPPER wire, not copper clad aluminum. You'll probably have 15' between the battery and starter and at that length you start to lose amp carrying capacity.

I would run a 2 gauge to the starter. Again, if it's a fine strand it will be flexible enough to go where you want.

If you are grounding to the frame use at least two ground locations, one on the drivers side rail and one on the passenger side rail. Then add some grounds from your powertrain to the body/rails. I have my block grounded, cylinder heads grounded to each other, [passenger cylinder head grounded, transmission grounded and starter grounded. If you have an old ground strap laying around I would braze or spot weld it to an exhaust pipe and ground it too.