Help! Truck batteries loosing voltage.

[randyn]

Hi All,



I left my truck sit for about a week and the batteries were down around 9 volts. I checked after they wouldn't crank truck enough to start. Later disconnected the smart charger my camper dealer installled & this seemed to reduce the drain on the batteries, but they still loose several tenths volts each night... . After driving my truck to work & back 50-60 mi. the voltage will be about 12. 67 the next morning it will be about 12. 27 etc. that seems excessive as it will be lower in few days than a disconnected battery on diff truck..... Should I take to dealer? The recent recall re: pcm connector makes me think that may be part of problem????



RandyN

 

[ntillm01]

I don't know about the recall, but you have something draining the batteries. I've left mine not running for a month, and played with the radio and accessories in that time working on it, and it had plenty of power to start.

Two big questions:

1) How old are your batteries? In some cases, older batteries develop an internal short in one of the cells, effectively causing a drain on themselves internally.

2) What all is connected to the batteries? I can't tell from your post what kind of camper you have. If it's a slide-in connected to B+ all the time, what inside the camper is on, and shouldn't be?

 

[RMcCulloch]

RandyN,



Do you have a refrigerator in that camper and, if so, is it turned on?



You might want to investigate the possibility of installing a battery isolater between the truck and camper batteries to make sure that the camper can't draw down the truck batteries. Of course, if you don't have seperate batteries ...

 

[B.G. Smith]

If you have a camper installed or are hooked up to a trailer, a propane detector will run the battery down pretty fast. Check the voltage with the truck running, it should be 13. 4 to 14. 5 with headlights and AC on. bg

 

[randyn]

I seem to have left out most of the pertenant info... .



Truck is 2003 purchased just about a year ago. Charging voltage is about 14. 1 volts. Within a few minutes of shutting the engine off in the afternoon the voltage is about 12. 5 volts. The next morning the voltage will be about 12. 27 volts.



The slide in camper is not now connected, but the smart charger the camper dealer installed is supposed to cut current to the camper when the turck battery voltage is below about 12 volts so as to prevent draining truck batteries. The camper battery gets charged w/ truck alternator or batteries if that voltage is above 12 volts.



I disconnected the smart charger from the turck battery (actually the circuit breaker), so it can't be draining the truck batteries.



Is there an easy way to check for current draw or internal short in one of the batteries?



I have added a Prodigy brake controler and a hydrolic winch. I have disconnected the electric control for the winch, but the Prodigy is still connected. I think it shuts off w/ the ignition key off.



?????????????????????



Thanks for any advise!



RandyN

 

[K5IP]

Can you find a multimeter with an ammeter function on it?

If so, disconnect both battery ground cables and measure the current flow (ammeter in series with either one of them) With all loads/accessories off, there should only be a few milliamps of current, not enough to dischage your batteries in a few weeks.

If this current is very low, and all else seems ok, try leaving the negative cables off both batteries and let them sit for a few days. Then, before reconnecting, check the open circuit voltage of each battery individually. If one is significantly lower than the other (more than a few tenths of a volt) you may have a battery with internal leakage.

When these two batteries are tied together in parallel the leakey one will also discharge the good one.

Good Luck

Rog

 

[clem]

If your voltage is going down to 9volts sounds like you have 2 shorted cells. reason each cell makes about 1. 5 volts. good batts will read 12volts when almost dead. and the way the Batts are connected one will kill the other. Sounds like a trip to Walmart good luck

 

[ntillm01]

I'm with clem and K5IP, it sounds like one of your batteries could have a bad cell or two, pulling the other one down. The good one pulls the other one up when you check it, making it look like you have a good 12volts.



This could be true even though they are really only a year old.



The ammeter check will tell you if something else going on.

 

[PLaFrombois]

As others have pointed out, you might have a faulty battery. You can have them each individually checked to see what battery may be bad, or you can go out and buy the biggest, baddest batteries that will fit in the battery tray.



Paul

 

[randyn]

Thanks for all the advise!



I disconnected the ground from both batteries, and then charged one of them for few hours on 2 amp setting. The v. of the battery I charged was about 12. 7 about 1/2 hour after charging. The v. of the other battery was 12. 4 After letting the batteries sit overnight, they were both about 12. 44 mid day when it had warmed up some. Reviwing my notes I think they would have been 12. 27 w/ grounds connected, so I decided I have a drain in the truck wiring. When I re-connected the ground of the 1st battery, I heard something click. If I had to guess, it was some sort of a relay or solenoid valve. Fuel cut off maybe???? I will try the ampmeter hook up on the ground wires next I guess.



RandyN

 

[B.G. Smith]

Also, there is a small fuse, about 3 amps in the fuse box by the door labeled IOD, (ignition off draw). You might try pulling it when you start searching for drain. ASnything draining with this fuse off should not be. bg

 

[DHoleman]

Did the problem start only after the camper came along, I'd start troubleshooting the wires to the camper even though the third battery is not hooked up, like lights or something other that runs on 12v. Also an altenator that is not or does not have the amperage for the third battery will not charge to full capasicity.

Auto Zone or Advance Auto will check either batteries, or aternater free of charge... DH

 

[K5IP]

Sounds like your batteries are ok.

The click you heard is not normal. You are probably picking up a relay when you make the connection. Try removing and connecting the ground cable again. If the click occurs again you can locate the problem by having someone else make and break the connection while you look/listen for the suspect. Even when know which one it is, you have not necessarily finished the job. Now you need to find out why it is picking up. Just knowing which circuit you are working with should get you started on the right track.

My 95 did something like this one time. It would discharge the batteries overnight and relay was pulling in. Before I could find out which one it was, or why it happened, the fault went away and has never occured again.

Good luck and keep us informed.

Rog