[Griz]

I've been having some battery issues lately and would like to know what the normal voltage output one should see from the alternator when traveling down the road. Mine reads from a high of 14.1 volts to around 13.8 when moving down the road and drops to 13.2 at an idle at stop lights etc. This is with lights, radio and fan on. Is this normal or is the alternator not putting out the right voltage? The reason I am asking is my truck after doing several quick start/stops while moving the trailer around the yard and out of the carport etc., the next day sometimes it won't start without jumping the batteries. The batteries are only 7 months old.

Thanks,

Griz

 

[RT]

My voltages run around the same with the exception my voltage doesn't drop that far at idle. You could still have a bad diode or some other parasitic draw pulling your batteries down.


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[Griz]

My voltages run around the same with the exception my voltage doesn't drop that far at idle. You could still have a bad diode or some other parasitic draw pulling your batteries down.


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Thanks RT...I am a little suspicious there is something draining the batteries along with a poor output from the alternator at idle. This last October I had both batteries replaced for the same reason...no start. I thought my problems were over but this is the second time it has done this since I replaced the batteries. If I run the truck on the road I don't have an issue.

 

[jeepwillys]

I hate electric gremlins. Mine was a hot wire that wasn't attached to any fuse box. So once it chaffed and grounded to the frame, it never blew anything. Never noticed it when i was checking for parasitic draw. Hope you can find it.

 

[Griz]

I hate electric gremlins. Mine was a hot wire that wasn't attached to any fuse box. So once it chaffed and grounded to the frame, it never blew anything. Never noticed it when i was checking for parasitic draw. Hope you can find it.

Thanks jeepwillys...it is a weird problem that is for sure. I've parked the truck after driving it and after a week or more it will start right up. But if I use the truck to move the trailer around the yard with several stop and starts while I am doing it, the next day it won't start...but not always. I am thinking my alternator might be the cause...or I have one or more flaky batteries, but not sure yet.

Griz

 

[bugman]

It sounds like you may have either one or two weak batteries.

When you are stopping and starting a number of times the batteries are not getting a full charge and keep wearing down where they won't start after sitting overnight. I would charge them up good and then have them load tested along with having the charging system tested.

 

[Griz]

It sounds like you may have either one or two weak batteries.

When you are stopping and starting a number of times the batteries are not getting a full charge and keep wearing down where they won't start after sitting overnight. I would charge them up good and then have them load tested along with having the charging system tested.

Bugman after charging the drivers side battery with my smart charger. I reconnected it in circuit and moved to the passenger battery and started charging it. I went back and read the voltage of the driver's side battery and it read 10 volts. What the heck so I disconnected it and it still read 10 volts. I was a little suspicious of this battery because it didn't take much to charge it to full charge. So back to the passenger side...it took forever to reach full charge...so I now have no confidence in either battery. Like I said earlier these were new batteries in Oct 2015. I am thinking I will have them replaced.

Griz