Battery/alternator help

Van-go

Van-go

Not an old man
Joined
Dec 11, 2014
Location
Greensboro
So I’m confused. Need some help.
My dually batteries are not staying charged.
2013 f350 6.7 powerstroke

truck started and ran fine yesterday.
Tried to start it today and nothing. No lights. Nothing. Jumped it off. Ran fine. Drove for an hour. tried to start it again after a couple hours sitting and it wouldn’t start but it would run lights etc.

New batteries a year ago
Both tested fine at advance. Just low charge

Disconnected both batteries and turned in headlights etc. alternator ran everything without batteries.

With both batteries hooked up and running volts are at 13.4 average

without batteries hooked up running it is reading 14.1

Can’t figure it out.

I thought it was the alternator, but why would the batteries be drained down overnight when it started the night before unless something is drawing power sitting.
 
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All voltage readings are at idle.
 
Alternator is probably bad. Make sure batteries are charged, unhook alternator over night and see if it will start next morning.
 
89wrangler said:
Alternator is probably bad. Make sure batteries are charged, unhook alternator over night and see if it will start next morning.
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Are you saying the alternator is drawing current when the truck is off?

it’s been idling in my driveway for 2 hours and now it’s reading 14.1 volts at idle with batteries hooked up.
 
Yes, had a friend with same issue. Would stay energized and drain battery overnight. Not saying that is your problem, but unhook the wire is an easy check.
 
Could also have 1 bad battery, like a friend of mine did. He had bought 2 standard batteries from Orilly's. Less than a year old. They checked alright, but 1 had a short in it. The voltage would go crazy with both hooked up, but run fine with just the good battery hooked up. He got Orilly to take back the batteries, & installed 2 of their glass mat batteries.
 
If both batteries test good on a load tester separately (if testing in the truck you have to disconnect at least one ground cable), and the alternator is charging then you have a draw. It could be the alternator as suggested above or any number of things staying powered up or randomly coming on.

My mom had a 00 Impala that started killing batteries, I couldn't find a draw whenever I'd check it but once or twice a week it needed a jump. The car was kept in the garage usually, but one night it sat outside due to something filling up the garage. That night they noticed yellow lights flashing in the window in the middle of the night. The body computer died and would randomly trigger the light flash but not the horn for a panic alarm. In the garage it went unnoticed for weeks.

PS:. Never ever disconnect batteries with the engine running on anything with modern electronics on it. The batteries stabilize voltage fluctuations at a minimum and worst case the alternator can output well over 20v with out a reference. That will fry expensive electronics like sensors or computers, of which a 6.7 powerstroke truck is full of if you aren't lucky.
 
Tim C said:
If both batteries test good on a load tester separately (if testing in the truck you have to disconnect at least one ground cable), and the alternator is charging then you have a draw. It could be the alternator as suggested above or any number of things staying powered up or randomly coming on.

My mom had a 00 Impala that started killing batteries, I couldn't find a draw whenever I'd check it but once or twice a week it needed a jump. The car was kept in the garage usually, but one night it sat outside due to something filling up the garage. That night they noticed yellow lights flashing in the window in the middle of the night. The body computer died and would randomly trigger the light flash but not the horn for a panic alarm. In the garage it went unnoticed for weeks.

PS:. Never ever disconnect batteries with the engine running on anything with modern electronics on it. The batteries stabilize voltage fluctuations at a minimum and worst case the alternator can output well over 20v with out a reference. That will fry expensive electronics like sensors or computers, of which a 6.7 powerstroke truck is full of if you aren't lucky.
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Great info. Hopefully I didn’t fry anything! :eek:


89wrangler said:
Yes, had a friend with same issue. Would stay energized and drain battery overnight. Not saying that is your problem, but unhook the wire is an easy check.
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It’s unhooked. I’ll report back in a few hours when I get up.

rodney eppes said:
Could also have 1 bad battery, like a friend of mine did. He had bought 2 standard batteries from Orilly's. Less than a year old. They checked alright, but 1 had a short in it. The voltage would go crazy with both hooked up, but run fine with just the good battery hooked up. He got Orilly to take back the batteries, & installed 2 of their glass mat batteries.
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One of my buddies told me the same thing. With the alternator unhooked like I just did, would one shorted battery still drain the other? I’d hate for it not to drain and I replace the alternator thinking I fixed my issue.
 
Test batteries after they sit overnight after being fully charged with an actual load tester - a high current load basically. I'd bet one or both batteries are weak/dead cells. The tester advance has doesn't actually load the battery, simply measures voltage and temperature. And yeah, never disconnect batteries to check alternator, the batteries act as a damper to the voltage swings output by the alternator and can cause spikes that can blow out electronics or can kill an otherwise good alternator as they use avalanche diodes (designed to fail if voltage exceeds about 19v on most altys). Also you can check for excess current draws by inserting a ammeter on the negative side (with just one battery) but you need to wait 10-20 minutes for all the computers to go to sleep. Best way to connect the ammeter is to disconnect the negative cable, jumper it to the negative terminal, connect meter, then unhook the jumper. The inrush current of hooking up the meter to an unhooked cable can be enough to blow the fuse in the meter. Allowable draw after 20-30 minutes is on the order of 5-10 mA iirc. That being said, I'll bet you got bad battery or two.
 
a_kelley said:
Test batteries after they sit overnight after being fully charged with an actual load tester - a high current load basically. I'd bet one or both batteries are weak/dead cells. The tester advance has doesn't actually load the battery, simply measures voltage and temperature. And yeah, never disconnect batteries to check alternator, the batteries act as a damper to the voltage swings output by the alternator and can cause spikes that can blow out electronics or can kill an otherwise good alternator as they use avalanche diodes (designed to fail if voltage exceeds about 19v on most altys). Also you can check for excess current draws by inserting a ammeter on the negative side (with just one battery) but you need to wait 10-20 minutes for all the computers to go to sleep. Best way to connect the ammeter is to disconnect the negative cable, jumper it to the negative terminal, connect meter, then unhook the jumper. The inrush current of hooking up the meter to an unhooked cable can be enough to blow the fuse in the meter. Allowable draw after 20-30 minutes is on the order of 5-10 mA iirc. That being said, I'll bet you got bad battery or two.
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After disconnecting the alternator last night, I let the truck sit for 7 hours. Connected it this morning and it started right up.
 
a_kelley said:
Bad diode in the alternator or a faulty regulator.. sounds like you isolated the issue.
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Yep you can verify by checking amp draw with alternator both connected and disconnected with the key off, amp draw shouldn't change. Or leave it hooked up overnight again and see if the alternator is warmer than the surrounding metal before starting it the next morning, that's a sure fire sign it's the draw, of course it'll probably kill the batteries again.
 
So what's the charging voltage from the alternator currently reading?


Nevermind, just saw the other post. 14.1 sounds just slightly low, depending on the state of battery charge at the moment, but it's plausible.
 
Fabrik8 said:
So what's the charging voltage from the alternator currently reading?


Nevermind, just saw the other post. 14.1 sounds just slightly low, depending on the state of battery charge at the moment, but it's plausible.
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That was after driving around town and idling for a couple hours. It should be closer to 14.5-15 per multiple ford forums
 
At my old job my company truck was an 07 Powerstroke. It would kill the batteries within a few hours, but the alternator was charging the batteries. It wound up that even though it was charging them, when it wasn’t running it would kill the batteries. New alternator fixed it.

01-07 Chevrolets were bad about that too. There’s a way to test it with a volt meter but I don’t remember how. Seen it on YouTube.
 
So just a thought, I wouldn’t trust Advance to tell you if the battery is good or not. I’d test it at a reputable shop.

Ive had the same technician at Advance give me multiple diagnosis of a battery, the same day, within 10 minutes of each other.
 
rockcity said:
So just a thought, I wouldn’t trust Advance to tell you if the battery is good or not. I’d test it at a reputable shop.

Ive had the same technician at Advance give me multiple diagnosis of a battery, the same day, within 10 minutes of each other.
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They just hook it up to a machine and give you a print out. Then proceed to say “looks good”
I’ll definitely get them tested elsewhere
 
Fwiw harbor freight has a carbon pile battery tester for roughly 50 to 60 bucks that looks similar and works just as good as this Mac tools one we have at work.
KIMG0334.JPG
I have the hf version at home. That and a decent charger and you can do your own testing and forget about advance or auto zone.
 
a_kelley said:
If you unhooked the alt & it didn't kill the battery in the same time it would have, it's the alternator. I was simply enlightening as to what went wrong internally.

Oh and this style tester works well also.
View attachment 303714
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So I haven’t done anything to the truck and it’s been doing fine. Just a little perplexed.
 
You must have threatened the electric demons enough to leave you alone... For now.

Honestly though, you'll find out if it acts back up. Any possibility that the dome lamp was left on or something like that?
 
My Jeep would do that sometimes and it was actually cause the glove box wasn’t shutting all the way and the light in there was staying on.
 
a_kelley said:
You must have threatened the electric demons enough to leave you alone... For now.

Honestly though, you'll find out if it acts back up. Any possibility that the dome lamp was left on or something like that?
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So I think may have figured it out. If I leave the key in the ignition it kills the battery. With nothing turned on, the first time it died, the key was in the ignition. Left it in last night, it was dead this morning.
Not sure what that means, but I’ll just not leave a key in it.
 
Wish I’d know you left your key in it. I’d come over there and mess with you. Turn it around one night, move it one parking spot over. Put it in 4 low.

I’m assuming you have another key, or use the key code to unlock it, but I’ve seen a lot of people just knock a window out when I key was left in a vehicle, and Fords are notoriously easy to break into.
 
77GreenMachine said:
Wish I’d know you left your key in it. I’d come over there and mess with you. Turn it around one night, move it one parking spot over. Put it in 4 low.

I’m assuming you have another key, or use the key code to unlock it, but I’ve seen a lot of people just knock a window out when I key was left in a vehicle, and Fords are notoriously easy to break into.
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I only leave a key in it if I’m having some beers. So I don’t loose the key lol. PS I only have 1 key and no door code thingy
 
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