So my Jeep has sat for 4 months or so and I went to fire it up.and to no.suprise the battery was dead. I jumped it and let it run for a but then took off down the road. Then the volt gauge jumped all the way up to 19 and it died. Tried to start it again. Battery us dead. Jump it again and same thing, volts jump and it dies. So I get it back home full the battery with water and stick it on the slow charger. Put another battery in that I had lying around that was for a Toyota Tercel. It's obviously a little small for it at under 500 CCA but I just did it to move it around. I noticed that at idle my volts would drop when i would turn on any electrical accesories. Had it tested at auto parts and they said battery was going bad. Ok.Had it in there for a day or two and stuck the original one back in. Starts and drives fine for the 1/2 mile back to my house from my fathers garage. Then today go drive it up to my fathers and the volts jump.up to 19 again but it doesn't die so I put my multimeter on it and it showed around 12.2 or so while running. Yesterday when I put it in it was at 13.6 when running. I shut it off and do some other things. Go out to start it and no power to anything inside. Multimeter shows 12.1. Go back to start it again and works perfect. also this is with new terminals and connectors on the battery side.

 

Start by cleaning all of the grounding point not just the battery. Also check the battry cables by bending the cables. If you hear a crunching sound or if they feel brittle you need to change them out. Give that a try and let us know what you find. If you still have the same problem we can go from there.

 

Ok. Will do when I get a chance.

 

Do you know where all the ground points are? If not they would include battery to the fender, oil dipstick, rear of the head to the firewall, 2 on the coil (If it doesn't have coil packs) and if your starter is covered in oil remove it and clean the mounting area between the starter and engine block, That is also a ground point. Clean them even if they look clean. Use a wire brush or some sandpaper and make sure that they are nice and shinny. Hope it takes care of your problem.

 

Ya. No coils. It's a 99. Don't think it has anything to do with starter since I wasn't getting any power inside the jeep.

 

Dead diode or bad voltage regulator may be frying your batteries

 

The volt gauge wasn't even right though. Showed maxed out but my multimeter showed 12.XX

 

Right. But you should be reading about 14.5 off the alternator anyways. As far as the gauge check the ground on the headlight switch

 

Where is this ground?

 

I hope that was distilled water, and not tap water.


Of course, since it sounds like the battery is shot anyway, I guess it doesn't matter with this one.

 

So I went out the other day and tried to start it but it didn't have enough juice to turn it over quick enough. Then today it started just fine and volts showed good at idle. Dropped down to about 14 with all electronics on. it was quite a bit warmer today though. So maybe the battery is just starting to go enough to where when it gets under a certain temp it just don't have enough power.

 

I wonder where the term "Cold Cranking Amps Rating" came from...

 

Battery tested bad. Free warranty replacement.

 

Sooprise.

 

New battery in. I'm still getting some voltage drop at idle sometimes and lights dimming. Think alternator is going bad too?