pscottjr

I have read many of the threads regarding battery drain..etc. I know the steps. However, I would perfer not to have to go through those if possible.

Put new battery in car about a week ago. New and working (first new one was a lemon). Have not driven the car in about three days and went out last night and would not start. Battery dead. Took battery out and put on my battery charger. Charged in about 5 hours was fully charged and check with a meter as 12 volts. Today, I was able to start the car. (NOTE: removed a DVD player from rear, connected to radio, that I will not use and I never knew if it was on or not)

Clean ground and all terminals before starting. Honestly, I am not sure that I did not have one or more of the courtesy lights on (on, not off when door closes) daughter I and I were checking how they worked that day. Have since turned off all courtesy lamps.

After restarting with newly recharged battery. I drove around for awhile and watched the voltmeter. Normally just barely above the 12 volt area. This is with a/c on medium and radio on only. Tried with lights, parking lights, radio, a/c at full ..... about 12 volts in stop and go traffic. Stopped turned car off. Went to pick up daughter at school and check all again (no lights on) and voltmeter was barley below below 12. Stopped to buy some vodka for a martini on the way home. After that restart voltmeter was again at barely above 12 volts. The only thing that was different was when I picked up my daughter I locked/armed the alarm system and when I went to the liquor store I didn't (lock at school, leave open at liquour store......)

Before I go through the search for a problem routine what should the voltmeter be reading during normal driving, idle, with and without full load (lights, a/c, radio brake lights, etc). I am a little concerned that the altmeter may not be working fully or that the belt is not tensioned correctly. The book says "needle should be between 12-14 volt range".

The car has a factory alarm system. I have not locked or engaged the alarm this evening and will check out all tomorrow morning.

Am I a little pariniod about the voltmeter readings?

Jim M.

The voltmeters are historically inaccurate. Instead get a VOM (volt/ohm meter) and check at the battery (below the spare tire). Should have at least 12 volts, usually 12.5-12.8 VDC. Start the car and check again. Now with the car running you should see 13 to 13.6 VDC. Anything less than 13 then check at the big post on the passenger side of the engine compartment, if still not 13 then check down at the alternator. If you get 13 volts at the alternator then clean connections until you get 13 at the battery with the car running.

There are a few things that can stay on when you shut the car down. IE. glove box light, courtesy lights, door marker (the red light in the end of the door) lights, a radio or amp not wired correctly, sticking relays that don't shut down etc. Normal battery drain should be about 20MA and not go over 40MA.

Jim Mayzurk
93 GTS 5-spd

WICruiser

My in dash volt meter is irratic but when it is working it reads approx. 13.5 volts after initial start and then slowly drifts down to just slightly over 12 volts after about 25-30 miles of driving.

I have confirmed that the battery is seeing the 13.5 volt reading after initial start so I suspect the other readings are fairly accurate.

As Jim points out, check the basics first. If your battery is being drained in a day or so from a full charge there is a fair amount of current going somewhere. It may be hard to isolate but take your time and you will get it sorted out.

JG928S4

open door, see if red lights on doors on, push in switch, wait 30 seconds and see if lights go out, if not that is the drain, that's what was up w/my car 1 1/2 years ago, fixed switch and never a battery drain problem since. (too easy, I guess I was lucky)

Alan

What the voltmeter on the dash says could be false so you have to get a seperate reading from a reliable meter. You can do this at the front jump post more easily.

Either your alternator is not charging the battery or you have a parasitic current that discharges the battery when its parked.

The easiest way to determine this is testing the voltage on the jump post when running (say idling at @ 1.5K rpm). Using a voltmeter if you don't see at least 13V you are not charging the battery and running the car is depleting the battery.

if you do see well over 13V then you probably have a current leak - which couls have been a light left on or could be somethig else.... if all the light are now off when parked - you just need to leave it for a few days again to find out?

If you don't drive it much and you fully charge the battery and still it runs flat in <1 week of not running it - you definately have a parasitic leakage current issue...

Alan

Emickelsen

Man, this all sounds so familiar. Where in the world have I seen/heard/expierienced this? Hmmm? Just can't put my finger on it...Oh ya, this entire weekend at Sharktoberfest!!! Amazing. So glad you brought it up, thank you. I will check the light thing. My volt meter reads 12.3 everywhere. If it turns out to be the alternator/regulator, Is there anything special I need to know befor I buy a new one??

BTW, FWIW, I made it back to bako just fine. Go figure.

WallyP

If you still have the original alternator, my suggestion is that you find a good aluto electric shop - not a general repair garage, not an auto parts store, but a shop that does nothing but rebuild alternators, starter and generators - and have them rebuild your alternator. They can usually do some upgrades at the same time.

This way, you know that you have the correct alternator, with the cooling cowl, etc.

Emickelsen

I think thats about $1000 worth of free advice, and seems to be the general concensus. I agree, and that is what I plan on doing

Alan

Its likely that the alternator can be improved - but do check if it is the alternator not charging the battery or is the battery getting drained as the car sits - unfortunately both issues are quite common on 928's and many cars do have both issues...

The dashboard alternator light not coming on does not mean the alternator is fine (or is still charging the battery) - it just means it han't completely failed (yet?)

Alan

SharkSkin

Parker, in my experience the dash voltmeter itself is pretty darned accurate, within .1 volt -- BUT it usually reads low because of resistance in the many connections between the gauge and the battery. Here is what I would recommend:

1) Check voltage at battery posts
2) Check voltage at ground point and + terminal on battery(not the post, the cable end)
3) Check voltage at jump post
4) Check voltage at power feeds on front of central electric panel(fat red wires).

If the voltage is not within less than .1 volt at all four points, you need to clean the connections. For example, if there is a .1V difference between 1 & 2, pull the cables off the battery and clean the terminals. Anywhere you see a voltage drop, clean all connections between the two points.

Also note the difference between the voltage on the battery posts and the dash gauge reading; you will have to mentally calculate the offset. For example, if the gauge reads 11V and the battery reads 12V, then just add 1V to whatever you see on the gauge. Obviously, the ideal approach is to just clean all the connections until it reads correctly, but for the short term just compensate mentally.

Also note that early alternators are notoriously weak at idle. IMHO, this is because the alternator only turns at 2x crank speed, unlike most cars. This problem is annoying enough on my 5-spd, where I have my idle set to the upper end of the spec to compensate. The problem is much worse on auto cars, since they idle much slower in gear.

Also, even a new battery will never output full power again once it has been dead for more than a few hours. Have that sucker load tested before you go any further, and don't let it go completely flat again until you resolve the problem.

SteveG

Well, it is fair enough not to want to go through those steps, some have, and after hours to no avail throw in the towel for a trickle charger; I'm afraid it's one or the other. There are threads here on the convenience of a permanent installation. OTH, depending on how badly the elect system was hacked, it is nice to eliminate the drain.

Emickelsen

I took my car to very reputable battery shop today to have them look into my problems (which are very similar). I found out my battery is good, even under a load test. The problem is the alternator is only putting out half a charge. That would explain the 3 or 4 months between experiencing these problems. Even the technician thought it was wierd. It was only putting out 13 volts, and that was a while after starting the car. At first it was not charging at all. Kookie!

To the rebuild shop, the alternator will go, young skywalker!!