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Discussion Starter #1
I just read about 5 threads with people having the same problem, but none of them ever said what they did to fix the problem.... here is the scenario...

truck is an 01 f250 7.3l single alt motor. I have had it for a few months now... Truck never had any starting issues... One day I go outside to start it get a few weak cranks then all the under dash relays start clicking and what not... So I jump the thing using my 1.8l vw yeah that took a while... I drive the truck around the rest of the day turning it off and starting it no problem. I figure it was just an odd ball thing. I park the truck 2 days later I go to use it and batteries dead. So I took them to the autozone they said the batteries were no good. Okay so 200.00 later I figure problem solved... Then 2 more days pass, dead truck... I jump it run it all around town, turning it off and on no problem...

Volt guage gives me a good reading when the truck is running. alt is newer, the batteries are less than a week old... What the hell could be drawing enough power when the truck is off to kill 2 batteries in less than 12hours?

The old batteries had a little corrosion on the terminals nothing crazy. I cleaned everything real well before putting the new batteries in...

Problem started after I had cleaned the engine bay out perhaps some simplegreen got somewhere it shouldnt have? I cant imagine that messing something up tho...


pics for clicks.
 

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Could be the alternator. They have a built in regulator that could be bad allowing the batts to drain. Alternator would still charge fine if just the regulator was bad.
 

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Easy way to test is to disconnect the alternator overnight.
 

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Discussion Starter #4
I actually did see that in an archived thread. I just went and bought a new digital meter, and had it on the batteries both reading about 12.33-.34 and when I unplugged the alt the voltage jumped up to 12.36-.37 I am going to leave it unplugged a while and see if it helps... Sucks because the alternator is still kinda new...

Its also very strange the alt would work fine, and yet still drain the batts. Would a parts store alternator tester show its messed up? I might pull it, and run it over to get tested real quick.
 

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Yeah, a parts store should be able to test the alt for you. It's a 10-15 minute job to remove and replace, so you can do it in their parking lot.

If the batteries have been dead, charging them with the alternator can take it out. That's what may have happened to your relatively new alternator.
 

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Discussion Starter #6
I took the alternator into the parts store, they said it tested fine. So I put it back in the truck, drove around all day, got a good charge on the batteries. then unplugged the alternator, and let it sit over night. truck fired right up. I guess the parts store test doesn't show if that diode or whatever is in there went bad. Now I need to get another alternator... sucks that one tested and was putting out like 15.8 volts.
 

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Battling the same problem on my 01. Less than 6 hours to drain both batteries. Initially suspected it was a battery problem. One was marginal -it had frozen- but the other was fine. Bought two new, 885 cca amp batteries. Spun up and fired. Six hours later the starter would barely spin. Put the batteries on a slow, overnight charge and pulled the GPR; I wasn’t getting a click and it’s the only thing I can imagine that would pull that kind of power that an I have a history of GPRS crapping out. It rattled so I replaced. Still same problem. Batteries died. Did a parasitic battery draw test. Consistently getting 130mA draw. Pulled every fuse. Twice. Tried it with each battery I can’t think of anything that might be unfused. I am at wits end. Gonna put in battery cut out switches until I figure this out. Suggestions?
 

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If a diode went bad in the alternator, that will draw the batteries down in short order. Check for that by disconnecting the large lead on the alternator. If the batteries stay up, you need to replace the alternator. If you remove the serp belt and reconnect the large lead on the alternator it may try to spin like a motor. That's a sure sign the diodes are bad.
 

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And once you get all that sorted out, then get yourself one of these White-Rogers GPR and you won’t keep having to replace them:

 

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If a diode went bad in the alternator, that will draw the batteries down in short order. Check for that by disconnecting the large lead on the alternator. If the batteries stay up, you need to replace the alternator. If you remove the serp belt and reconnect the large lead on the alternator it may try to spin like a motor. That's a sure sign the diodes are bad.
Thank you! I’ll give that a try this weekend!
 

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Had the same issue, and did what klhansen said with disconnecting the big wire.
Batteries OK w/ wire off the alternator, batteries dead the next day w/ wire connected.
The funny thing is that I bought the rebuilt alternators from an auto parts store, “lifetime” warranty on the alternator.
Went through three new alternators. Each lasted a few weeks, then the rectifier/diode bridge shorted, and the batteries died. I got to be pretty good at swapping alternators, but could not drive anywhere far from home or risk being stranded.
Anyway, eventually gave up on the cheapo 3rd world rebuilt alternators, and bought a Leece-Neville.
Took much research to locate a Leece-Neville that was not a counterfeit!
Worth the effort, has been trouble free for over a year now.
 

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Had the same issue, and did what klhansen said with disconnecting the big wire.
Batteries OK w/ wire off the alternator, batteries dead the next day w/ wire connected.
The funny thing is that I bought the rebuilt alternators from an auto parts store, “lifetime” warranty on the alternator.
Went through three new alternators. Each lasted a few weeks, then the rectifier/diode bridge shorted, and the batteries died. I got to be pretty good at swapping alternators, but could not drive anywhere far from home or risk being stranded.
Anyway, eventually gave up on the cheapo 3rd world rebuilt alternators, and bought a Leece-Neville.
Took much research to locate a Leece-Neville that was not a counterfeit!
Worth the effort, has been trouble free for over a year now.
Funny thing about that life time warranty. You get to replace these parts for as long as you can still turn a wrench. It's a common practice that if you kill your batteries and the alternator is bad you need to replace the batteries as well. Even if they test fine they are junk. Untill you replace the batteries you will keep burning out alternators. Batteries dont like to be drained all the way and charging them back to 100% is difficult at best. Another mistake people do is jump start the truck and drive it around to charge the battery. Alternators are not like generators. Generators will charge a battery where as alternators are not designed to do that. Sure they will kind of charge the battery but it destroys the diodes inside because they get hot and fail. Buy good parts and batteries and put your tools away.
 

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That didn’t fix the problem. Even with a alternator disconnected it’s still has a draw.
You'll need to hook up an ammeter between a battery post and the cable that would normally be connected to it, open the door, wait till the interior lights go off, indicating the modules have gone asleep, then start pulling fuses while observing the ammeter. Normal draw with everything off is 50mA or less. When you see the current drop off from the initial reading, the problem is in the circuit fed by the fuse you just pulled. You'll need a wiring diagram ideally, or at least a map of what each fuse feeds (in your owner's manual). You may have to do it multiple times to narrow it down, as some fuses feed other fuses.
 

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You'll need to hook up an ammeter between a battery post and the cable that would normally be connected to it, open the door, wait till the interior lights go off, indicating the modules have gone asleep, then start pulling fuses while observing the ammeter. Normal draw with everything off is 50mA or less. When you see the current drop off from the initial reading, the problem is in the circuit fed by the fuse you just pulled. You'll need a wiring diagram ideally, or at least a map of what each fuse feeds (in your owner's manual). You may have to do it multiple times to narrow it down, as some fuses feed other fuses.
That was where i started this saga. Twice on each battery. Same 130mA draw. I am wondering if there is a fuse block somewhere I don’t know about? Checked under the dash and under the hood fuses. The only add on is/was a trailer brake
controller.
 

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When you say twice on each battery, you only need to connect one battery for the test. One thing I forgot to mention is that you have to keep both batteries connected (one thru the ammeter) till the modules go to sleep, and then disconnnect the battery without the ammeter connected inline. An '01 will just have the two fuse boxes. The one under the hood at the driver's side and the one under the dash. With a wiring diagram, you can tell which fuses are downstream of others (most of those will be under the dash), and you can pull those first. If you pull a fuse that powers the GEM, and put it back in, it will wake the GEM up and you'll have to wait till it goes asleep again to continue, so the best way is to pull downstream fuses and leave them out. It's a pretty involved process, so you have to do it methodically.
There's a possibility that you have a main feeder from the starter relay (that goes thru fusible link wires) that has a cruddy connection that's leaking to ground, causing the draw you're seeing, but that's really pretty remote. I wouldn't hurt to check all the connections for cleanliness, though.
 

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Wow. Thank you. Hadn’t thought about waking up the module by re-inserting the fuses. I’ll try this again. Looked at the fusible link connect the starter relay. They looked intact: no squishy or bulging insulation.
again, thank you for the tips and quick response.
 
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