low power dimmed lights new battery HELP!!

92' xj 234000 miles

im having some power issues when i first start it in the morning my battery gauge is @ 9 in the red zone and the jeep runs like dog poop check engine light comes on lights are dim

then after i drive it like that for about a mile it magically powers up battery reads 12-14 lights are good runs awesome check engine light goes away WTF!!!!

anyway i was curious what this might be my battery is good.....could it be bad grounds from the the starter or the alternator? anybody else ever have this problem?

I would say a bit of both. The alternator doesnt really charge much at idle, but ti should be charging enough to keep everything bright.. I would check your grounds and clean them. Its a '92 so they have a good 19 years of crap on them. Also if your battery is draining quickly when the jeep is off i would check for drain. Definitely check grounds. If the engine strap is green it definitely needs replaced. I would not replace it with another strap though. Get a 2 or 4 gauge battery cable and replace the ground strap with that. Not anything to do with the recharging system but it will help elsewhere.

There's only one way to deal with your suspicious grounds and this should be done as a matter of course as a maintenance item.

Remove, clean, scrape, polish til shiny all mounting points and wire terminals.

Just gandering at them will accomplish nothing. I've never yet been able to "see" if grounds were in good shape.

When my alternator was going south it would start the day at about 9 volts, then pop up to normal after a minute or so of driving. The time needed for it to start running normally got progressively longer, then it would only start charging after tapping it with a long screwdriver, then hitting it with a hammer, then hitting it with a BIG hammer, then it would no longer charge.

Bad brushes. You can swap the alt with a rebuilt or pull it and change the brushes if you are so inclined.

To be sure, when it is running at 9 volts in the morning, give the alt a wack with the hammer. If the voltage pops up right away, I would say it's the brushes.

I think BrokenSockets has it with bad brushes. You're at about the right mileage for that.

You can replace those brushes if you're lucky, but be prepared for the possibility that the slip rings are also damaged, and also the possibility that the little screws holding the brush carrier into the alternator will be rusty and very hard to get off without shearing. It can be done, though. If the slip rings aren't gouged out, new brushes will work fine. If the slip rings are damaged, new brushes will still work, but of course they won't last for another quarter million miles. You can get the brushes in their carrier and just bolt them in, or get the brushes alone and solder them into the carrier.

Do not sandpaper the slip rings if they're dirty or scorched. Something like crocus cloth will work, but if you roughen the surface they'll eat the brushes.

thanks for the fast responses guys im hoping it aint my alt. but if it is oh well im going to check all my grounds tomorrow

Shane_92-XJ said:

thanks for the fast responses guys im hoping it aint my alt. but if it is oh well im going to check all my grounds tomorrow

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Refresh your grounds no matter what. Can't just look at them and wiggle them. Remove, clean, scrape, til shiny at the wire terminal and where it mounts on the engine and firewall. Accept no substitutes.

Do you have access to a Volt meter? If you can get a hold of one you wont have to guess anymore. I think they might rent them out at Autozone. A really cheap one from harbor freight might work "ok" for some basic testing.