Battery Trouble

[adams_samm]

Whenever I connect the negative terminal to the battery, sparks begin to fly for just a second then it stops, then after that one of the ground wires begins to get really red and hot. It burned off the rubber around it. Nothing is happening to the ground wire connected to the negative terminal. The negative post is pretty beat up. What's going on?

[Stealthee]

Could be a bad battery. Could be a shorted wire.

[shorod]

If a ground wire is getting that hot, there is apparently a short circuit somewhere that is apparently not fuse protected. The path of highest resistance is getting hot which is likely why one wire is getting hot and melting the insulation but the large low resistance cable to the battery is not.

Has someone added a stereo system, alarm system, CB/Ham radio system, trailer brake controller, or similar? If so, check those systems to see if they are fuse protected.

The negative terminal on the battery is probably beat up from all the arcing. If the problem were with the battery you wouldn't have the sparking only when the cable is connected and the one ground wire wouldn't get hot because the short would be in or at the battery.

-Rod

[adams_samm]

Someone added a trailer brake controller some years ago, but it has always worked fine. The last time we drove the truck is a couple days ago. We hit a few bumps and the lights flickered. Hit a few more and the car shut off. We looked inside and the ground wire going from the negative post was melted down, and the negative terminal was split in half. Now when we got a new terminal and ground wire we started having this problem with the other ground wire.

[shorod]

With the battery disconnected you should be able to measure for resistance from the negative battery cable connector to the positive battery cable connector. With the amount of current draw you're experiencing, that resistant is probably a matter of a few ohms or less. There's obviously something that is not fused properly or where a heavy gauge power wire is shorted to ground. You're going to have to do some inspection for any wires that are rubbing against the chassis or engine, etc.

-Rod