Random Dead Batteries **Mystery solved**
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Cross-Country
Joined: Jan 2016
Posts: 83
Likes: 1
From: Climax, MN
Random Dead Batteries **Mystery solved**
I bought my 96 CC DRW in mid October, I only have about 2000 miles on it since. About 6 weeks ago I went to drive it and the batteries were dead, I charged them for a bit and it started fine. The next morning they were mostly dead. The next time I wanted to drive it I charged them again and again fired off fine, It sat for a couple weeks till last weekend I got in it and it started fine. Last night I took it when I went out for supper and it started fine again, this morning mostly dead again. Anybody got any thoughts?
TIA.
TIA.
More Turbo
Joined: May 2012
Posts: 542
Likes: 1
From: New Milford, CT
Something is draining power and a lot of it.
Turn your key off, all power things off, pull key from ignition, and keep doors closed.
Get your multimeter out. Set it to the amps setting. Start with a ten or twenty amp scale (sounds like you have a big drain). Disconnect both of your battery negatives, and connect your meter in series on either of the batteries.
After that remove the negative lead on the other battery and leave the positive lead on. Put one end of your multimeter on the disconnect negative lead and the other lead on the negative battery terminal. If you have a draw this will show it. I know on gas vehicles you shouldn't have more than a 50 mA draw. Not sure if it's different on a diesel.
Anyways, if you do have a draw, leave the meter connected and begin pulling fuses one by one until your meter reacts when you pull a fuse. When that happens you've found the circuit the draw is in. You can figure it out from there.
Turn your key off, all power things off, pull key from ignition, and keep doors closed.
Get your multimeter out. Set it to the amps setting. Start with a ten or twenty amp scale (sounds like you have a big drain). Disconnect both of your battery negatives, and connect your meter in series on either of the batteries.
After that remove the negative lead on the other battery and leave the positive lead on. Put one end of your multimeter on the disconnect negative lead and the other lead on the negative battery terminal. If you have a draw this will show it. I know on gas vehicles you shouldn't have more than a 50 mA draw. Not sure if it's different on a diesel.
Anyways, if you do have a draw, leave the meter connected and begin pulling fuses one by one until your meter reacts when you pull a fuse. When that happens you've found the circuit the draw is in. You can figure it out from there.
Lead Driver
Joined: Oct 2003
Posts: 8,476
Likes: 37
From: Madison, WI
There's no "secondary" battery. The batteries are in parallel, connected to all circuits. So just disconnect both negatives and connect the meter in series on either battery. As for current draw, our '95s draw about 20 mA key off, doors closed.
Laughing Gas
Joined: Feb 2014
Posts: 774
Likes: 25
From: Reno, Nevada
If your batteries are good you can almost leave your headlights burning all night and it'll still start in the morning. I'm exaggerating but my point is that you would need to have one heckuva battery drain to kill both of them overnight and it's not very likely. If it were mine I would charge and then load test the batteries. If you have several vehicles a battery load tester is a good investment. Or you can drive down to an auto parts store, I think most of them will load test batteries for free. I'm guessing your batteries just need to be replaced. If it sat for a long time batteries will get sulfated and won't hold a charge.
Postmaster
Joined: Mar 2004
Posts: 3,897
Likes: 8
It sounds like your problem is very intermittent. Can you pull out your key anytime or just when it's in the off position. I had an employee that would leave the ignition in acc when he parked the truck. It was ok for overnight but if it wasn't noticed the truck would have to be charged first
i ain't rite
Joined: Mar 2005
Posts: 65,492
Likes: 5,552
From: Marlboro Mental Hospital.
^^^this ^^^
a bad diode in the alternator will let it charge fine, but then drain the batteries when sitting. if the alternator is warm after 8-12 hours sitting, it needs replacing.
another thing to remember, it takes hours to charge batteries.
so if you jump start the truck and drive it for 1 hour, you only put about 1/4 charge in the batteries and they will fail a load test.
to properly charge batteries you need 2 hour 40 amp fast charge, then a slow 2 amp charge for 12+ hours.
a bad diode in the alternator will let it charge fine, but then drain the batteries when sitting. if the alternator is warm after 8-12 hours sitting, it needs replacing.
another thing to remember, it takes hours to charge batteries.
so if you jump start the truck and drive it for 1 hour, you only put about 1/4 charge in the batteries and they will fail a load test.
to properly charge batteries you need 2 hour 40 amp fast charge, then a slow 2 amp charge for 12+ hours.
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Cross-Country
Joined: Jan 2016
Posts: 83
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From: Climax, MN
Winner Winner Chicken Dinner, you sir nailed it. I took it to the shop yesterday and installed my TS6 and 6637 and today it was dead again. I popped the hood and the alternator is warm, it must have a diode shorting out? Thanks for the tips everyone!
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Laughing Gas
Joined: May 2012
Posts: 855
Likes: 5
From: Central Oregon
No dash lights, alt won't charge???
Post Fiend
Joined: Dec 2009
Posts: 15,505
Likes: 18
From: Livoina,La
If the alternator light in the dash goes bad then the system will not charge. The bulb is part of the charging system. When the filament breaks it's like having a broken wire. Think Christmas lights....when one stops working the whole string goes out. It took us four brains and two weekend to find this on a buddy truck.
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nookiemonster55
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Jun 27, 2012 08:28 PM