An odd thing happened to my 1995 Jeep Cherokee recently. I was able to start it up one day and drive to work without problems. When leaving work I noticed the dome light didn’t turn on when I opened the door. I put the key in the ignition and when I turned it to the ACC position it just made a very short beep then nothing. Tried cranking it but there was no turnover whatsoever. Ok, I thought maybe I left the door ajar and the interior lights on all day or something like that. Got a jump. It started up right away. Drove for about 20min or so then went home. Turned off the car then tried to turn it on again. Nothing. No turnover sound, just nothing. Not even a dim dome light when the door was opened. Took the battery out and charged it overnight.
The next day I put the battery back in. It started up without hesitating. I looked at the battery meter on the dash and it was between 13v and 14v like it usually is. Drove to the store for some shopping. 15min later I came back and noticed no dome light and absolutely nothing when I tried turning it over. I put one of those portable battery jump starter things on and was able to get it to start up. When I got home I once again turned it off then tried to turn it back on. Just like before there was nothing. I put a volt meter on the battery posts and it read 12.4 volts. When I put the volt meter on the battery clamps it read only 10.2 volts. I cleaned the contact points between the volt meter and the battery clamp but it still read 10.2v. I’m going to try cleaning the posts and the clamps tomorrow but am not sure if that will make a difference. Is this a sign the battery needs to be replaced? (Note: the battery has gone through a couple periods of being dead for extended periods of time over the past 3 years. I’m not sure if this would damage it or not.)
CoNick — ",,, I put a volt meter on the battery posts and it read 12.4 volts. When I put the volt meter on the battery clamps it read only 10.2 volts. I cleaned the contact points between the volt meter and the battery clamp but it still read 10.2v."
For the battery to read 12.4 V and the voltage across the cable clamps to read 10.2 V, two conditions must occur:
current must be flowing out of the battery; and
there must be electrical resistance (i.e., corrosion) between the battery terminals and the cable clamps.
It does sound like you need a new battery, but why guess? I can’t tell you for sure, but you likely can get it tested for free at a local auto parts store. They generally will do this for free and in general they tend to do a accurate job.
I don’t suggest just replacing parts, especially when checking it properly will greatly increase the chance that you will be able to fix the problem on the first try.
What do you think? Clearly you know your way around electrical circuitry and testing. I suspect you came to the conclusion that the battery must be replaced but you are hoping on a long-shot play to save yourself some $75 or so. I wish I had some suggestion for you, but it seems a foregone conclusion: replacement.
Those extended dead times for the batt do indeed damage it…they dont like that much. I think the guys have a good grasp on this thread.
Keep in mind to clean and grease and tighten all the connections when you put in the new batt…buy that 4 dollar battery pole wire brush…its an internal/external brush…shaped like a little bullet… Indispensable little tool
Thanks for the help. I don’t mind spending money on a battery. I just wanted to make sure it wasn’t indicative of a larger problem ( besides me not taking care of the battery proerly.) It’s a project car of mine that I’ve slowly been learning on so it doesn’t get driven frequently.
If you want to be dead certain slow charge the battery for a few hours with the battery cables disconnected…
Check the voltage across the posts. It should be about 12.6 volts. (Six cells at 2.1 volts each.)
Allow the battery to sit all evening (cables still disconnected) and recheck the voltage across the posts. If it’s down in the 11s and 10s the battery is dying.
If you wanted to get even more picky and if the battery has removeable filler caps you can even go down row probing the electrolyte from one cell to the adjacent one to pick out a bad cell if that happened to be the case.
Charge the battery over night. Take it to the parts store and ask them to load-test it… A simple load test makes batteries confess all…If it passes the load test, then your jeep has a problem…
If your battery reads 12.4 volts between the posts and 10.2 from clamp to clamp then you have corrosion between the post and clamp. Clean and tighten that and you will start right up.
There should be no discernable difference between a reading at the posts or the clamps.