Yesterday I was driving my Expo on some pretty rough pavement. I was taking it slow, but something clearly shifted around, and I started to see smoke coming from under the hood near the battery. I popped the hood, and the negative terminal was completely melted into a puddle of lead, and the negative cable was arcing juice to a small piece of post that hadn't yet melted. I grabbed a stick and moved the neg. cable to a safe(r) place.
When I tried to sub in a secondary battery, as soon as the second post is connected, the negative post starts smoking and melting again.
I clearly have some ground wires exposed and touching the frame someplace (seems the most logical place to start to me).
Any advice here would be very welcome, but in particular, methods to trouble shoot using a volt meter. I used one last night connecting pos to pos, neg to neg, onto the battery cables only, I didn't even have a battery in at the time. When I turn on the 1000 amp setting, it would register it on the meter. This suggests to me that there is a closed loop all the way from my pos. terminal to the negative.
Now, with the battery out, and the keys all the way off and out, I should not be able to send a charge from one set of terminal wires to another (pos to neg for example) should I? That loop should not close until I turn the key in the ignition correct?

Sorry for the mini-novel. Any help would be so gratefully accepted!

 

Follow the positive cable it's full length to see where the insulation has worn through.
It's not the negitive side because it's already the grounded side to the engine block and the frame.
Voltmeter is not much help on this fault.
Good luck.

 

Moved to correct forum.

 

Thanks, I definitely will. I ran out of time today, we'll take a close look at her tomorrow.

 

Make sure the braided grounding strap is properly secured to the frame. Many times the braided grounding strap terminates at/on the firewall.

 

Did you figure out the problem? Please share.