Wire/cable sizes

[-83MONTESS-]

Can someone explain the difference between 1/0 and 0 gauge? When I relocated my battery to the trunk I used 0 gauge car audio cable. It really didn't seem thick at all but I figured 0 gauge was 0 gauge. Well after driving around for a while I realized my volts jumped back and forth from 12 to 14 on the gauge. When I got home I noticed that the ground cable from the battery to the frame was very hot. My buddy suggested going with some 1/0 welding cable and as I search I find 1/0, plain 0 gauge, and stuff that says 1/0-0 gauge on it. Whats the difference and what should I use?

 

[pontiacgp]

I have my battery in the trunk and run a 4 gauge wire with no problems. BMW have used a 4 gauge wire from the battery in the trunk for decades. I ran a 8 gauge ground to the body and to the frame from the trunk. I grounded the engine from the frame to the engine and I grounded the body in the front from the frame. This is the 23 lbs battery I have in the trunk up on the ledge behind the back seat the company sells wiring kits that are 4 gauge.

 

[-83MONTESS-]

So if 4 gauge is fine my 0 gauge car audio cable must be fine right? If thats the case then why would the ground cable be so hot? I also have an intermittent slow crank still. Seems like if I go to crank the starter it will crank very slow at first then speed up. Does it randomly no matter the temp of everything....

 

[CWPottenger]

Technically 0 gauge and 1/0 are the same. Unless you are pushing some serious amps, your wire is plenty big enough. 0 gauge can handle up to 240amp load. When a wire gets hot it is either from excessive load, poor connections, corrosion. I would verify cable connections are clean and tight. Is the frame connection clean metal or painted and only ground is the bolt contact with the thin edge of the hole?

 

[Judge Mills]

Just guessing here, but check your grounds, and check that you have enough of them. The 0 gauge audio wire is made for heavy loads. The only difference I can think of is a more flexible (softer) casing, which may be transferring more heat than the typical automotive wire, which seems to have a heavier casing.