Chassis to NEG Battery Terminal size

[exitwound]

I've been having a lot of problem with corrosion of my terminals on the battery. Another no-start today led me to find this:



I've been using a non-original large gauge wire to go from the NEG battery terminal to the chassis ground on the firewall. I believe it's the source of my problem. Connecting this to the NEG clamp leads to a lot of surface area to rust/corrode.

The NEG cable I'm using to go to the engine block just happens to be red, so look past that. It has a little wire connected to it apparently. Could this wire be used safely to connect to the firewall?



(No cleaning has been done yet to the terminal clamps/wires)

[Outback Porsche]

Not recommended.

Current flowing in the chassis neg wire is the same as the current in the pos battery wire. Best to make it the same gauge. Also best if it's multi stranded - it's all about surface area.

Cheers

[exitwound]

I've gotten conflicting messages on this from various sources. Some have said it's fine. Others have said it's not. Anyone else have any thoughts?

[choinga]

These cars are notorious for nagging electrical issues - this is not a spot where I'd attempt to cut any corners. I'd go with as big and flexible of a cable as possible - and as mentioned, twisted, multi-strand is preferred.