Hi guys.

Wow this thing is frustrating.

First of all, thanks to all who responded to my previous posts. Got those issues sorted.

Right now, I'm baffled because after having my battery tested at autozone and being told that the old battery was "bad" and needed to be immediately replaced, though no power issues were present, I installed a new one just to be on the safe side. During the install I accidentally broke off the bolt on the ground wire attached to the battery. I bought an aftermarket replacement cable, because I thought the $80 OEM part was excessively expensive, and installed it.at the same time.

My issue now is that within a week of putting in the new battery, the car wouldn't turn over. I pulled it out and took it back to the place I bought it. They recharged it, and their test found that the battery had no issues.

I re-installed it, took the car for about an hour long drive, all the while the battery meter progressively got lower. This morning it was totally dead. I jumped it with a hand held jump starter. It ran until I disconnected it from the device, but then died. Hooked the battery up with cables to my other car for an hour, and it started independently of the cables. I let it sit for about an hour while writing this post, and she still starts, however the battery meter looks lower than I remember it being right after the charge.
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When I first got the car, I saw a battery not charging message flash briefly on the warning display, but it was only on for less than a minute, and has never come on again.

So, if the car isn't telling me that the battery isn't charging, and the new battery tests fine, why in the world isn't it holding a charge? Especially when it is turned off over night?

Any help would be much appreciated.

Thanks again.

Disconnect the negative cable, charge the battery, and leave it disconnected overnight. Or don't you have a battery charger?

Do you have a multimeter? It would help if you could measure the voltage at the battery with the engine running. At this point we don't know if the alternator is charging. The dash gauge is not really functional.

If the voltage at the battery is 13 to 13.5 with the engine running that's good. But it might be discharging back through the alternator when the engine is off.

Your alternator is dead/dying.

As per Mikey and RJ - your alternator is suspect (what a rotten job replacing that is!) You can get rebuild packs so you don't necessarily need to buy a whole new alternator.

2nd in line is the ignition switch. Look at the switch with the key out. There should be a tiny shutter closed at the top and preventing you looking inside. Its job is to shut the car's electrics down and save battery power. If the shutter is stuck open the battery will drain overnight just enough to stop it starting up. Fix it by spraying WD40 ON THE KEY and pushing it in and out a few times. Do that once a year.

Also if yours has the Harman Kardon stereo with the amp in the trunk the amps are known to short out and will drain the battery overnight. If the amp is warm or hot even if the car has been shut off a while thats a good sign. Try unplugging the cables to the amp or pull its fuse and see if the battery goes dead. That happened to my '97.



Dave

I changed my alternator a few weeks ago. Had all kinds of error messages start appearing on my dash and noticed that the voltage gauge wasn’t moving off of 12 Volts when the engine started. Ordered a Denso from Rockauto and it took a few hours to install. Not a bad job it you work on cars. Air filter housing must come out for access.

A BIG thanks for this forum. It was from reading the forum that I knew that a low battery can cause all kinds of faults to appear on my dash. Otherwise there would have been some major “freaking out”.

Thanks for the advice. My question is that if it were the alternator, which was my first thought, wouldn't there be a message on the display telling me that the battery wasn't charging?

Thanks for the thought. I do have the HK system and was fiddling around with the amp and the old motorola phone system before this all started. My intention was to replace he AMP and a few of the speakers, and was frankly surprised to find an AMP in the system because the sound quality is not great. I will pull the factory AMP and replace it to see if that fixes the issue. Thanks to all for the posts, and I will report back when I figure out what it was.

Here is my thread on these amps if ti turns out to be the problem...



Dave

Would that not be redundant to the battery gauge?

Hi RJ.

I purchased a multi-meter and will post numbers once the battery reaches a full charge.

I ran a parasitic draw test on the car before I plugged it in to the charger and found a 4.5 amp draw on the system when the car was off. I pulled every fuse and it still maintained a 4.5. The Amplifier and CD changer are still disconnected, by the way.

My question is does this indicate that the battery is, in fact, discharging through the alternator while the vehicle is off? If so, should I just replace the alternator, or is there a connection that I should check/clean before I go to the trouble?

Thanks all.

I seem to recall reading that you can replace the regulator, and that may be faulty. But I think you need to remove the alternator and have it tested.

I haven't had a alternator problem in so many years that I am not a good source of information.

I'm sure someone more knowledgeable will stop here and help.

This is the type of thing you're looking for -

NEW LUCAS ALTERNATOR A127 REPAIR KIT -RECTIFIER -REGULATOR -SLIPRINGS MASSEY | eBay

Just look up the real alternator type first.
Alternatively look locally for an 'alternator clinic'. These companies will fix your old unit in front of you.

Start the car now and see if the alternator is charging.

It could be discharging through a multitude of places. The alternator is just one possibility.

So, after I got the battery charged to near ful, I started the car with the multimeter attached. It dipped a bit on start, but remained above where it needed to be to verify that the cc amps in the battery are good. However when it was running, it barely moved above where it was when it stopped. So the alternator is giving a little spark, but no where near what it should be.
I'm thinking that since it is working slightly, this might be why the on board computer is not sending me the 'battery not charging' message. However, whenever I drive it it lasts for maybe 5 minutes before it is discharged to the point that the car wont run properly.
So I found an alternator on Ebay that came out of an xj8 but will also fit my xk8. An amazing $34.00 salvage with a "will work upon arrival" guarantee. Ebay so Rocks! *if it actually fits. lol.

I'll keep posting until we get to the bottom of this.

Oh, I failed to mention. I left the battery connected over night. Morning multi-meter reading 1.54 volts. No Bueno.

Keep us posted but the actual numbers you got would have been useful.

Not sure how you measured battery amps (?)

What were you measuring while starting and running? Volts? Actual numbers please..............

If your battery was fully charged, it would *not* go flat with just 5 minutes driving. Things don't quite add up.

Mikey- I think in your last para. you meant to type 'would not go flat', correct?

Ooops, you're right. I'll correct it!

Thanks!