Battery drains...
Thread Starter
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Elder User
Joined: Apr 2010
Posts: 518
Likes: 0
From: Mount pleasant, michigan
Battery drains...
Well the 78 Ford F150 battery is draining....i have just recently replaced the battery in it, and its on its second battery...ive taken the alternator to get tested and it passed...well my battery isnt holding a charge and i believe something is draining on it, where should i start?
Hotshot
Joined: Apr 2009
Posts: 14,333
Likes: 247
From: Stanley, VA
Other than a bad battery my first thought would be shorted diode in the alternator but the test should have caught that.
All you can do now is start chasing the electrical system. For this, if you don't already have one, you'll need a VOM (voltmeter). It doesn't need to be a real good one, for this a "cheapie" will do.
First, disconect anything you know is drawing power when off (radio).
Then disconect the positive battery cable. Hook the voltmeter probe to the positive battery terminal and the other probe to the battery cable end.
If the meter is showing voltage there is something drawing power. Pull all the fuses and circuit breakers and check again. If its still showing voltage there is a short in the wiring somewhere. If it doesn't show any voltage, start replacing fuses. Check each time you replace a fuse. If it shows voltage there is something in that circuit that is draining the battery. At least this helps narrow down where the problem could be. It'll still take some detective work to find.
All you can do now is start chasing the electrical system. For this, if you don't already have one, you'll need a VOM (voltmeter). It doesn't need to be a real good one, for this a "cheapie" will do.
First, disconect anything you know is drawing power when off (radio).
Then disconect the positive battery cable. Hook the voltmeter probe to the positive battery terminal and the other probe to the battery cable end.
If the meter is showing voltage there is something drawing power. Pull all the fuses and circuit breakers and check again. If its still showing voltage there is a short in the wiring somewhere. If it doesn't show any voltage, start replacing fuses. Check each time you replace a fuse. If it shows voltage there is something in that circuit that is draining the battery. At least this helps narrow down where the problem could be. It'll still take some detective work to find.
Thread Starter
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Elder User
Joined: Apr 2010
Posts: 518
Likes: 0
From: Mount pleasant, michigan
Ahh this sucks, eletrical is definetly now my strong suit...ok ill try! I had the truck running, and the alternator was putting out over 13volts off idle...and thats a brand new battery too.
