Dancing on the hood


#1

A caller on today’s show describes an odd electrical problem. While having 5 people dance on the hood the battery shorted out to the hood, and supplied stage quality sparks and smoke.
The caller had already replaced a burned out ground strap; the car starts, but many of the electrical accessories will not work. He would like to know how to fix it. Click and Clack suggested replacing the fusible links.
I would like to add mounting a piece of plywood over the battery to the suggestion. This protects the terminals from shorting again.
Seriously I would invest in a 12V test light, which can be had for a few dollars. Check the bargain bin at your local hardware or car parts store. The test light looks like a transparent ice pick with a wire coming out of one end. The transparent portion lights up if 12 volts are applied between the clip at the end of the wire and the sharp tip.
Connect the clip end to the negative battery terminal, and poke the wires you would like to test with the sharp end, right through the insulation. If the light lights you have a good connection. Once done put a dab of paint over the hole in the wire insulation to keep out water and to remind you which wires you checked.
The short (~2" long) fat portions of the wires leading to the battery terminal are the fusible links. Do not poke into them. Instead check the wires coming out of the fat portions, on the side pointing away from the battery.
Make sure to use a test light, not a volt meter. The volt meter will claim circuits are good, even if they are weak in reality.
Don’t forget to check the ground connections. To check these put the test light clip on the positive terminal.
I hope the car was not running when the battery shorted. If it was I suggest visiting a junkyard on an “all you can carry for one low price day” and buying the electrical system out of a suitable donor vehicle.


#2

If I let 5 people dance on the hood of my car, the car would have to be one step away from the graveyard. I don’t see the point in fixing this one. Bye bye car.


#3

This sort of reminds me of a similar issue with one of my cars. I took the battery out for some extra work space, but did not tighten the bolts down far enough when putting it back. Needless to say the battery bounced around, luckily no cracks that leaked acid.

But I was wonderring why I was losing power driving over small bumps - meters go out, etc. I never thought of shorts as there is a rubber boot on the positive pole.

However, the vibration rubbed a hole through it, and it shorted against the top of the hood whenever going over a bump. A small burn hole now is visible on the hood where the battery shorted against it. I’m sure the shorts were doing a number on my alternator.

Now I need to make sure I bolt down batteries tight enough…