just less than 2 weeks ago i bought a new battery for my truck because the old old had a dead cell and yesterday i had to replace that one because it turned out to be a bad battery and now i'm haveing another problem w/ this battery i got now.

i don't think it is my alternator because when i jump the truck off i and disconnect the cables from the other car i still am getting 13.48 or so volts. but the only thing i think it could be is my electric fans that are on an adjustable thermostat but it don't really make sense because people run their big stereo's for hours but don't kill the battery but i come out there after a few hours or so and my battery is dead.

can it be that i put on a new grounding strap and some how that did something or could i have a bad alternator or voltage regulator when all of those parts are new too. all help w/ this matter would be greatly appreciated.

thanks,
daniel

 

First thing to do with any type of charging system problem is to make certain that your terminals are clean at the battery. Pull the terminals off and clean them up real good with a wire brush. Also, make sure you clean the ground connection at the block. You need to make certain that the battery is in good conditon before you start testing the system.

Since you are still showing 13.48 volts after removing the jumper cables, that tells us that the alternator is charging and the voltage regulator is doing its job. Get the truck running again and double check your voltage. Then turn on all your accessories- lights, radio, wipers, a/c, fans, heater, dome lights, etc. Then look at your voltage again. If it drops below 13v with the truck running, I'd change the alternator. You could use the same regulator but its cheap insurance to go ahead and change it also.

It's been my experience that when a voltage regulator goes bad, it allows the alternator to overcharge the battery. When the battery turns to toast, your voltage will indicate that the alternator isn't charging. Then when you install a fresh battery, if the alternator hasn't cooked itself, it will show a charging state again.

If your charging system checks out ok, you might have an accessory drawing power even when the ignition is turned off.

Good Luck-

Joe

 

I am having the same exact problem,what might be drawing power if the lights and radio are off?

 

Anything electrical can draw power even though it appears to be off.

To test for a power draw, disconnect your ground cable from the battery. Hook up a test light between the cable end and the negative post on the battery. If it lights up, you have a power draw. On some new stereos, the memory circuit will cause the test light to light up but it will be very dim- that's ok. It's when the light is bright that there is a problem.

If it lights up, have someone hold the light while you start pulling fuses one by one. When the light goes out, that's the circuit that has the problem. Then you have to trace it to see where exactly the problem is within that circuit.

Before you go through all that trouble, though, make sure of one thing- walk behind the truck and make sure your brake lights aren't staying on when you park the truck. Sometimes the brake light switch will need adjusting to keep this from happening.

I have seen where even an alternator can draw power from the battery when the car is off.

Good Luck-

Joe