Mechanics

BATTERY KEEPS DRAINING

1990 Ford Ranger

Electrical problem
1990 Ford Ranger 4 cyl Two Wheel Drive Automatic 130000 miles

My sons truck keeps draining the battery, even when it is turned off. It was jumped started about a month ago, and has had to be jumped several times since. We put a new battery in it, drove it to town(about 15 miles), it sat in a parking lot for 8 hours and drained that battery too! I do not know much in auto repair. I can not afford to, not do I want to be " taken" on these repairs. Thanks, MOM
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Davesmom
November 22, 2008.



Try this simple test first. To make sure alternator is charging the battery. If alternator is charging then we will need to trace what is draining the battery. Something left on? Radio/interior/exterior lights. Etc. Etc.

TESTING
CHARGING SYSTEM TESTING
NOTE: Ensure that battery is fully charged and battery connections are clean and secure. Check that alternator drive belt is adjusted to proper tension.

NOTE: When charging battery, remove ground cable before connecting charger. If booster battery is used to start engine, negative cable of booster must be connected to vehicle frame. Disconnect negative booster cable first.

Ensure that all accessories are turned off. Connect voltmeter to battery. Attach tachometer and start engine. Operate at 1500 RPM with no electrical load. Voltmeter reading should increase, but it should not exceed 2 volts above battery voltage. Reading should be taken when voltmeter stabilizes.
With engine operating, turn heater or A/C blower motor to HIGH position. Turn on headlights to high beam. Increase engine speed to 2000 RPM. Voltmeter should indicate a minimum of.5 volt above battery voltage.

Dave H
Nov 22, 2008.
Could this be something electrical. I'm pretty sure they guy who jumped started it the first time had the cable ends reversed. I was in the truck, so can't say for sure, but the cables looked a little melted to me.

Tiny
Davesmom
Nov 22, 2008.
This is definately an electrical fault. If the guy who jumped the car had the cables reversed then he could have fried the battery insides. Your first port of call should be an autoparts store to have the battery checked. Or if you have got a volt meter. Put red to+ and black to - on battery with engine not running. If your battery is holding @ 12.5 volts then it's ok. Leave the volt meter on for a few minutes to check it is holding there and make sure nothing is turned on in the vehicle. If it's holding the battery is fine. Now with the volt meter still on start the car and the battery should now be showing between 13 and 14 volts. If that is the case the alternator is charging. And we need to trace the drain.?

Dave H
Nov 22, 2008.
I had a brand new battery put in, and it started and ran, went about 15 miles. Parked it for the day, went to leave work and the new battery was dead. I sure there was nothing left on. How hard is it to trace back electircal problems?

Tiny
Davesmom
Nov 22, 2008.
It's very hard to trace electrical faults. They could be anywhere on the cars wiring which is miles of it? It could be that your alternator is not charging and the car is running on the battery all the time. If it is not getting recharged it will keep dying.

Dave H
Nov 22, 2008.
I have printed off all of the information you have given me. I will see if we can narrow down the problem. Thanks for the advice. I'll let you know how it goes.
Davesmom

Tiny
Davesmom
Nov 22, 2008.
No problem. Let me know if ya need more info/help

Dave H

Dave H
Nov 22, 2008.
It is definatly electrical. Is there a good method to finding what is shorted? Would I be better off taking it somewhere to find this problem? If so, is there certain questions I should ask a mech. To see if they are the best person for the job. Like I said, dealing with very limited funds. Thanks, Davesmom

Tiny
Davesmom
Nov 24, 2008.
Try this first. It's going to be difficult to trace the actual drain. Unless you have noticed something that is not working?

CURRENT DRAIN CHECK (WITHOUT TRIP COMPUTER)
Ensure all accessories are turned off. Disconnect either battery cable. Connect a test light between the battery cable and battery post. If light does not come on, no current drain exists. If light does come on, check individual circuits to find source of current drain.
CURRENT DRAIN CHECK (WITH TRIP COMPUTER)
Ensure all accessories are turned off. Disconnect either battery cable. Connect an ammeter between either battery cable and battery post. Allow one minute for system stabilization. If current drain is.05 amp or less, system is okay. If current drain is more than.05 amp, check individual circuits to find source of current drain.

Dave H
Nov 25, 2008.