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Battery Not staying charged???

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copedrake

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On my 85' GMC Sierra, I brought the alternator to be tested, they said it was ok. battery was tested and they said it held a charge. cleaned the connections at the battery and the alternator. there are no fuses blown and there is not any hot wiring straight to the battery.

when jumped, it charges the battery right under 14volts. turn the truck off and battery is dead....any suggestions? i have looked over the wiring that i could see to make nothing is shorted or burned... thanks for the help!
 
Something is drawing the battery, either a dead cell in the battery, which wouldve shown up during a test or a parasitic draw. I had a draw that would run my battery down over a 1 to 2 week period of not driving it. My problem ended up being the tach. It was wired with constant on and was drawing power even when off. So I jus switched it to a keyed circuit. Otherwise, jus check to make sure the ground from the battery to the chasis is good, not broken or corroded. Also look at your battery tray. Maybe a rusted torn up tray could be effecting it some how.
 
"Turn the truck off and the battery is dead."

As in immediate? Anything work, headlights, interior?

Check your connections beyond the battery posts?

If the starter is good and the battery is good and it's immediate then it's your wiring. If it's dead the next day it's parasitic.
 
yes the interior lights and radio will work until the battery completly drains out. if i were to start looking at the entire wire system involving the alternator, battery and starter, what should i be looking for?burnt wires, cut wires?
 
Burnt, cut, or frayed wires. Check continuity across the fusable links, check ALL the fuses, and check ALL the wiring, it could be anything (usually non-factory wiring) that is faulting and killing your battery. I had a PO wire in a second fuel tank, and that wiring later shorted and killed a battery for me, so it can be ANYWHERE on the vehicle

Also, if you've killed the battery more than like 3 or 4 times, you might want to go ahead and get a new one AFTER you have isolated and corrected the problem.
 
mechted said:
Burnt, cut, or frayed wires. Check continuity across the fusable links, check ALL the fuses, and check ALL the wiring, it could be anything (usually non-factory wiring) that is faulting and killing your battery. I had a PO wire in a second fuel tank, and that wiring later shorted and killed a battery for me, so it can be ANYWHERE on the vehicle

Also, if you've killed the battery more than like 3 or 4 times, you might want to go ahead and get a new one AFTER you have isolated and corrected the problem.
Click to expand...

+1....

It is almost always non OEM wiring like stated, I know mine was.

Also dont replace the battery til you get this sorted out. I was running Optimas, so they were staying strong as long as they could, that is why I didnt notice the problem for awhile. A weaker batt. wouldve given up sooner.
 
thanks for the advice, i am going to have to just keep on searching until this wire may be found, or whatever is faulting it up.

I remember on my old 78' powerwagon i had to replace the voltage regulator on the firewall, is there anything like this on an 85 GMC that could be like that that would be maybe adding to the problem?
 
How old is your battery? If it is anywhere between 3-5 years old i'll bet there is a bad cell in it.
 
4X4HIGH said:
How old is your battery? If it is anywhere between 3-5 years old i'll bet there is a bad cell in it.
Click to expand...
X2 espically if it is a Napa. I had a 15 month old napa gold battery that would not hold a charge. Took it to napa to have it checked. They said it was fine.
I had throurghly checked the car for a short and could find none. So I took the battery to wal mart to have it checked. Wally world said it failed their test.
Went back to Napa and raised hell... They mumbled something about their battery checker not working right lately and gave me a new battery. Mabe some Napa stores are better than others but I have been really dissapointed in our NAPAs service and parts and dont like to go there.
 
try pulling the fuse to your radio next time you get out of your truck. check connections and all of that. make sure your battery has fluid in it.

also maybe could be just me, but my battery was doing the same thing and my starter was weak. threw in a brand new starter and everything works great. it holds a charge really well and never fails to start.
 
How fast does the battery drain? Overnight?

Take the battery and have it tested someplace else.

Buy a volt/ohm/continuity tester. Check the batteries voltage with the engine off. Start it and check again. Should read 12v and 14v respectively.
 
BKinzey said:
. Should read 12v and 14v respectively.
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For those that dont know. There is a big diff. in the state of the battery between 12.1 v and 12.7 v.

Supposedly

12.7-13.0 is full charge,

12.4-12.5 is 75%,

12.0-12.3 is 50% charged.


So jus reading 12v doesnt mean youve got full power out of that battery. While it may not be dead and will start your vehicle, it is not fully charged.
 
easiest way ive found to see if there is a short or not is to disconnect the ground wire at the battery. if there is a lil spark then you have a short/draw.
 
better yet, test light between the cable and post...

If it dies immediately, it's gonna be the battery... If it takes a bit, check for a draw with the testlight and pulling fuses....
 
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