I didn't notice this before after leaving my truck for a week even, but recently if I let my truck sit for a couple days it will loose it's charge and will barely crank over (not enough to start atleast), a simple jump and it starts right up. Think it's my alternator, or do I need to replace the batteries?

 

Check the voltage at the battery terminals with the engine running. Should be at least 13.5 volts. If not, your alternator is gone. Check the voltage of your batteries with the engine off. If it's below 11 then they're probably no good. Have Autozone check them.

 

hey first off are the batterys full of water if that type. are the termials clean, are the ground wires ok. also did you ever do the power window mod that allows the power windows to work with the key off, that little light is a draw that will kill a bat. also are you leaving things plugged into the power outlets. think simple things before jumping into a alt replace. glove box light things like that. nexted I would go for the alt fuse. and so on another good thing to try is charge both batterys with a charger then disconect both ground wires and let them sit for a couple hours and see what the voltage is then. hope it help cmf

 

My '98 used to do that - and eat batteries as well as front brakes... I finally got Optima blue-top(marine) and no problems since.

 

thanks for the input i'll try that stuff. I think it's time for new batteries anyway, so i'll pick up some optima's to.

 

I don't know it if makes a difference, but it only started doing this since I did my gov arm adjustment. I had to leave the ignition on for a little bit to lift the fuel shutoff seleniod. Do u think that had somthing to do with it? Cheapest batteries I found were $169 a piece, lol. A new alternator is only $150

 

Have you checked for an ignition-off draw? Pull the IOD fuse and see if it continues, or check the current draw on this circuit.

 

I drove it enough today to build a nice charge, so i'll check tomorrow. The batteries seem good, I think it is some kind of ignition off draw, so i'll pull that fuse.

 

Have you got a multimeter? Put it on the battery with everything off and see what kind of current draw you have. Something may be drawing them down.

 

12 valves don't have the IOD that newer rigs have. Basically all there is just the clock and radio station sets.

 

It started today but it didn't seem to turn over like a full charge would, so I pulled the IOD fuse out, i'll see how the charge is tomorrow compared to today and that should say somthing.

 

I pulled that IOD fuse for about 5 hours, and went to start the truck (put the fuse back in) and it was almost completely dead. Anybody got any input for that?

 

Get the batteries tested. Sounds as if you got a short in one and it is pulling the other one down.

 

Yep, a dead battery will take the other one with it. That is why it is important to replace them as a set.

Some other good tips:

Make sure you have good clean grounds.

If you have a multi meter check alternator output and for anything drawing power with the ignition off. I've read here before about the seatbelt control module (under the seats) is sometimes a culprit in killing batteries.

I do not recommend marine (deep cycle) batteries. While they may work, they will not last as long as normal starting batteries since this is not an application they are designed for.

I do recommend the Optima batteries. They are top quality batteries, second only to those really nice Odyssey (dry cell) batteries. I installed a set of Optima red tops (size 34U) last August. They have not given me one lick of problems, and have not corroded any of the terminals. The terminals do not have any special coatings on them to prevent corrosion, they are bare. I always had to clean my terminals periodically when I had lead acid batteries, no matter what I did to protect them.

Heres a size comparison of an Optima vs. a normal lead acid (this is a factory Mopar batt). The Optima is smaller but puts out more power than the lead acid.

Battery specs :

---------------------------------- Lead acid ------- Optima
Cranking Amps (CA) @ 32°F ---------900 Amps -------1000 Amps
Cold Cranking Amps (CCA) @ 0°F ----750 Amps --------800 Amps
Reserve Capacity (RC) --------------Unknown --------100 Minutes




Hope this helps.

 

If you use the optimas take care about the battery tiedown bolts- the bolts will be much too long and on some vehicles there is a wire loom right below one bolt.
I used some wood to pad up the battery and used the stock bolts so I can go back if I want.

HTH

AlpineRAM