Help fixing hacked battery relocation

[turbo98eclipse]

Hey guys! Ive been gone for about 18mths, but I just picked up a 97 tsi the other day! It looks like the previous owner started to do a trunk battery relocation, but its a pretty bad job. Ive been reading on how to PROPERLY do the job, but I want to see if what he did so far was atleast satisfactory.

Im not tracking so I dont need a kill.

1st thing, he ran a 4 gauge wire straight to the starter. There is a small 8gauge wire to the fuel pump with a 30a inline fuse. When I turn the key the pump turns on so im assuming thats correct. Battery is grounded to both of the rear strut bar towers (two spots)

2nd, he ran 2 8 gauge wires up the the engine bay, where it looks like he planned on connecting them to the 100a alternator fuse and the b+ (the 4 white wires from the fusebox, twisted together to make 2 wires).

And he stopped there. No extra fuses or anything. I was planning on putting a 100a fuse right next to the battery at minimum. But I see everyone running 0 or 2 gauge wire with distribution blocks, etc... but if his setup is "good enough" then ill leave it alone. Im slightly confused on if I need to do something for the alternator or if itll still be ok as is.

Lastly, I havent worked on these cars in over a year, but I remember the ground for the starter being connected by the starter bolt. Since the battery is now in the trunk, how do I ground the starter? Is bolting it to the trans enough or do I need to have a wire from the mounting bolt to the firewall ground?

Thanks for the help guys, im glad to be back!

 

[TSiAWD666]

You'd want a fuse or a circuit breaker on the positive line next to the battery for safety, to help cover shorts in the wire from causing a fire in the cabin. I'm guessing you're using the stock alternator so a 100amp should be sufficient.

To ground the starter you ground the engine, so you could run a ground cable like stock from the engine to the chassis in the engine bay. I've read some arguments that our chassis is pretty poorly conducting due to its construction and it's more ideal to run the engine ground back to the battery, but I haven't seen specific data proving/disproving this and you'll get many anecdotes about how grounding straight to the chassis at the battery and at the engine works "just fine". So to start just try the engine bay ground.

You might want to re-do the 4 gauge wire to the starter as something larger due voltage drop over that distance and how finicky the starter is with voltage. Perhaps go to 2 gauge there. I would argue the same for the fusebox lines, replacing those two 8 gauge wires with a single two gauge, as you want as little voltage drop as possible from the alternator to the battery.

 

[TSicktalon]

To sum up what TSiAWD666 just said, more is always better with electrical stuff.

 

[turbo98eclipse]

Something like this being better? Im assuming I can run one 2 gauge and just split it vs running a separate line to the starter and a separate line to the fuse box, both coming from the battery?

This setup wouldnt require a dedicated line to the alternator correct? As it looks like its really just extenting the wires from the front to the back.

Thanks for the help!!

 

[TSiAWD666]

That looks like it will work just fine.

 

[turbo98eclipse]

I have everything wired up but as soon as I turn the key, all the power in the vehicle shuts off and wont come back on. It eventually came back on after 5 or so minutes. No blown fuses and my breaker didnt trip, so not a grounding out issue. Does this sound like its just a bad ground in general?

I used 1/0 wire for the main wire and the 4 white wires were turned into 2 4gauge wires.

Questions!!:

1) Why do some people run a dedicated wire to the alternator? Whats the advantage of doing that if it can still get power from the stock wiring?

2) Those 2 ground points use 4 gauge wire to 2 diff points, should I use heavier wire since I have 0 gauge for the power wire?

Issue was definitely a bad ground. Car now cranks.

But im still curious as to why some people run a dedicated wire to the alternator.