Dead batteries ?
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Elder User
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From: Leesburg , Fl.
Dead batteries ?
I have a '96 F350 , 7.3 ... After starting in the morning it always took a few minutes for the alternator to charge . Yesterday when I started the truck it took longer than it had in the past, then on the way to work the voltmeter started to go to discharge ( but still in the normal range ) . When I got out of work ( 12 hours later ) , the batteries where dead . My question is... Is it possible that the alternator has an internal short that drained the batteries ? Any ideas are welcome .
Fleet Owner
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From: Rio Rico, AZ.
Originally Posted by Briansshop
My guess would be to take a look at your glow plug relay-contacts might be sticking.
Brian
Brian
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Elder User
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From: Leesburg , Fl.
Originally Posted by Briansshop
My guess would be to take a look at your glow plug relay-contacts might be sticking.
Brian
Brian
Fleet Owner
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From: Rio Rico, AZ.
The easiest way to verify if the relay is sticking on is to see if there's power to the big post that goes to the glow plugs while the ignition is off. There will always be power to the other side, that's the hot side that comes straight from the battery. The relays will never be engergized with the key off. The glow plug light going off does not mean that the relay is switched off. That's one of the reasons that I decided to install a manual switch on the dash of my truck to turn on the glow plugs only as necessary to get the truck started, than they are off for the rest of the day. The engine smokes a lot more in the morning for the first minute, but I am smug in the knowledge that the glow plugs are not burning unnecessarily. They put a huge load on the alternator and I don't like running them without reason.
Worn out brushes will not drain a battery while sitting, but will prevent the alternator from recharging them back up after you use them to start the truck, run the glow plugs, etc.
Worn out brushes will not drain a battery while sitting, but will prevent the alternator from recharging them back up after you use them to start the truck, run the glow plugs, etc.
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From: Leesburg , Fl.
Thanks kwikk ! I had the wire harness under the valve covers replaced a couple of weeks ago , maybe they screwed something up !
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Fleet Mechanic
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From: MD
[QUOTE=blackf3504dr]Ok, dumb question ... when the glowplug light goes out , doesn't that mean the relay has opened ?
Nope, It stays on after the light is out or,not if the contacts are messing up.
Get it running and check voltage at batts - that will tell you if your alt. is OK
Brian
Nope, It stays on after the light is out or,not if the contacts are messing up.
Get it running and check voltage at batts - that will tell you if your alt. is OK
Brian
Last edited by Briansshop; Jan 7, 2006 at 09:56 AM.
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Elder User
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From: Leesburg , Fl.
OK ... I got the batteries back in , and it's not the glow plug relay ( no power at the "out" terminal with the key off ) . On the way home the voltmeter showed very little charge , however it did spike up to the middle of the range a couple of times . Tomorrow I will go to Auto Zone and have them test the alternator, but I really don't trust the help there ! Thanks for the input !!
Fleet Owner
Joined: Jun 2004
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From: Rio Rico, AZ.
Originally Posted by blackf3504dr
OK ... I got the batteries back in , and it's not the glow plug relay ( no power at the "out" terminal with the key off ) . On the way home the voltmeter showed very little charge , however it did spike up to the middle of the range a couple of times . Tomorrow I will go to Auto Zone and have them test the alternator, but I really don't trust the help there ! Thanks for the input !!
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From: Leesburg , Fl.
I went to Auto Zone this morning ( Sunday ) , The test while in the truck showed the alternator was not charging... I pulled it off and they bench tested it. The bench test confirmed it was not charging ( the tester would shut down in 3 seconds ) and read FAIL ! I installed the new alternator and so far so good . I have never had a bad alternator drain the batteries before . I will leave everthing hooked up over night and see if the batteries are still charged in the morning . Thanks guys !!
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From: Leesburg , Fl.
Originally Posted by Kwikkordead
Yeah, it's pretty hard to get it right the first time when the truck is 3000+ miles away. 
I went out to get the paper off the front lawn this morning and hit the "unlock button on the key fob and the doors unlocked and relocked ( Which they wouldn't do Friday night ) after setting all afternoon and last night . I'll take it for a drive later today ...