Do I have an electrical problem?

[LOGJOCKY]

Well I recently found out that when I put on my rear defrost, my battery charge gauge keeps getting lower until I turn off the defrost. Also everytime I use my power windows the gauge makes a big jump toward low charge. I changed my batterie cables about a week ago because they were big time corroded. It did not fix the problem however. Although my radio works now. Anyway is this a big problem, and whether it is or not, does anyone know what it is?

 

[aldive]

In wgat condition is your battery?

 

[LOGJOCKY]

as far as i know it still has 800cca. I checked with a cheap tester though. It also said my alternato was good.

 

[Alec]

Well obviously something is still wrong.

If all this happens with the truck running then it's probably your alternator (incl voltage regulator), or cables. If the alternator is good it will hide a bad battery while the engine is running.

 

[Opera House]

At this age it may be the grounding straps from the engine to the body. If you don't have any problem starting, this is likely the problem. Try running a #10 or so wire from the engine block to a screw that is really clean on the body. Remember the engine is electrically isolated from the frame except by the bearings that have a higher resistance. The dash voltmerer measures voltage to the frame. If you have a good voltmeter, you can put a heavy load on like headlights and rear defrost and measure voltage from frame to neg battery term. Should be less than 0.2 volts.