Jumped battery 3 times this week!

**edrex** · 10-09-2005, 08:32 PM

I need to know how to troubleshoot this. Either something is draining the battery while the car is parked, or the alternator is not charing the battery enough while the car is running and the system is going. Or its something I haven't thought of. In any case, what do I do about this?
Thanks.

**TruckinMP3** · 10-09-2005, 08:41 PM

Take the car to a parts store that will diagnose the problem for free.

They will tell you if the Battery, alternator and voltage regulator are working correctly.

You could try running for awhile with out the PC hooked up to power and see if it still happens.

**kevinlekiller** · 10-09-2005, 08:42 PM

To check alternator ; Check voltage when car is off , check voltage when car is on , if voltage is higher when car is on its still charging ( it should be over about 13.5 volts when car on , 14.4 is good).

To check if short : Unplug all stuff that you installed, check if car starts tomorrow.

**numbers** · 10-09-2005, 09:47 PM

And in the mean time stop jumping it. Keep that up and you're guaranteed to have a bad battery AND alternator.

**Bugbyte** · 10-09-2005, 10:21 PM

First, reduce the number of variables you have.

1. Get the battery tested. If okay, proceed to 2.

2. Unhook your computer and power supply. If it reoccurs, it is NOT your battery and NOT your power supply. Probably your alternator.

**Bigassbike** · 10-10-2005, 12:18 AM

I just went through the same situation. All the advice given so far is right on the money. Removing variables is huge! I did this first before anything else.

Next I went to my local autozone and they were very helpful. They tested the batteries. Both were fine but had low charge. They checked the alternator and it was ok. They check to see if there was a drop in voltage between the alternator and battery and there was. This could be caused by the voltage regulator or the fusible link between the two. The voltage regulation is done by the pcm/computer, so I prayed it wasn't that.

The first thing I did was to remove all the connections. I used canned air to blow out any snap in type connectors. I cleaned all connections at the battery terminals and had the system checked again, and there was no drop in voltage between the alternator and batteries.

Unfortunately the problem cam back. I was able to get me hands on a service manual for my truck, and started reading. It turns out that there is a temp sensor under the battery that tells the pcm how to charge the battery. When I modded my battery tray, I did not know this. My batteries sat flat on the bottom of the tray. The oem battery sat on small risers about 1/8th inch high to allow airflow to the sensor. I placed a piece of plastic under the new batteries so they would sit at the correct height. No more problems.

I hope this helps.

**aoLhaTer** · 10-10-2005, 12:42 AM

Bad bad memories about this

My problem was that my 150W Opus was draining my battery through the 5VSB line and it was draining so easily because my alternator was crap and wasnt charging my battery all the way (old car)

**edrex** · 10-10-2005, 12:46 AM

Thanks for all the suggestions!
I will get the battery tested in the morning and go from there. I unhooked the carPC for now to see if that is a factor.

**agentloveless** · 10-10-2005, 11:41 AM

Three posibilities:

1. Bad alternator

2. Bad battery

3. Bad circuit

Easiest to check for is the bad circuit. Check all your fuses. If the alternator does not get its field current, it can not generate electricity. If all fuses our good then you probably are getting it. Another way to check is to use a screw driver, while the alternator is on, it should have a magnetic field so it should pull at the screw driver if you tap it on the side of the alternator.

Second this to check is for the bad alternator. Best way is to use a multimeter and check the voltage. While the car is on it should be higher than when off. Any where from 12-14V.

Last, have the battery checked.

Good luck.

**TruckinMP3** · 10-10-2005, 08:15 PM

Originally Posted by agentloveless

Three posibilities:

1. Bad alternator

2. Bad battery

3. Bad circuit

Easiest to check for is the bad circuit. Check all your fuses. If the alternator does not get its field current, it can not generate electricity. If all fuses our good then you probably are getting it. Another way to check is to use a screw driver, while the alternator is on, it should have a magnetic field so it should pull at the screw driver if you tap it on the side of the alternator.

Second this to check is for the bad alternator. Best way is to use a multimeter and check the voltage. While the car is on it should be higher than when off. Any where from 12-14V.

Last, have the battery checked.

Good luck.

You left out voltage regulator...