Help! Brakes Done!...now electrical woes

[PodSquad48]

Spent the extra time this weekend finishing the brakes on my 48 P15. New shoes, master cylinder, wheel cylinders, etc... and I'm happy!

So I go to fire her up and she's struggling a bit to get going. As I go under the hood to prime her I notice the dreaded plastic burning smell. Long story short, the end of the negative battery cable is starting to melt. The cable is hot to touch, so is the starter relay... so is the cable from the relay to the starter! Could this simply be a bad relay thats keeping power flowing and overheating? I have a brand new Optima 6V and I hope I haven't ruined it! Any help/advice is greatly appreciated!

[Merle Coggins]

The cables are hot because the amp draw is exceeding their limit. What size cables are they? If they are too small this could happen. Or your starter is drawing high amperage. Or you were just cranking too long.

Merle

[TodFitch]

Could be as simple as 12v cables being used: They have higher resistance than 6v cables and will run hot. It could also be you have an issue with the starter.

[Scott1953]

Also, a properly sized cable with sufficient corrosion either at the terminals or under the insulation near the terminals will cause enough extra resistance to build up some serious heat. My wires were sized well enough but after having some starting and charging issues, I pulled them off and replaced them. Peeled back the insulation and found a lot of white/greenish corrosion. Heat in a wire/electrical component usually equals resistance.

Edited May 26, 2009 by Scott1953

[greg g]

Assure proper sized cable minimum 1 gauge, clean tight connections, proper grounding (pos ground), and proper ground cable to a good ground. If you have done recent painting do not assume your grounds are like they were before painting or undercoating.

If you do not have a ground from the body to the frame install one. If you painted the starter and ot the it mounting point it may not have a good ground conection tot he engine.