89 Vert. After starting, battery light is lit and volt gauge is reading 11.5.
Ten minutes of idling and battery light goes out with a reading of 13.6 volts.
Fairly new battery (2yrs).
This also happened about two weeks ago.
Mechanic checked alternator output after first incident and got a reading of 14.0 volts.
Drove car a couple of times in between these two incidents, no problems, but volt reading of (13.6).
Any ideas what this could mean.
Thanks in advance for any help.

 

OK, knee jerk reaction: The voltage regulator in the alternator is showing signs of going South. When cold, on start up, it reads low but after it warms up and sees a few RPM excursions past idle it begins to react as it should. This would account for your mechanic to see a perfectly functional alternator but you, early on, see one responding outside proper limits. If I am correct this condition could last a long, long time without bothering your driving. I would suggest you have the alternator tested under load, might tell you more.

 

Even though your battery is 'fairly new' at two years, it's really a crapshoot with auto batteries. Sometime you just get a lemon... not to mention the harsh environment the battery has to withstand inside of the engine compartment, really messes with it.

So lets take some easy steps to see if we can eliminate the battery as the culprit.

Step 1: Voltage reading on your dash is approximate AT BEST. So get a good working multimeter to check the battery at rest, and at idle. Battery at rest around 12.6 or above is pretty good. At idle the reading should be around 13.X or so. Remember, the battery also acts as a 'voltage regulator' of sorts.

Now if you're within range, great. If not, let's take this time to also visually inspect the Positive and Negative cables, and their connections to the battery. Check the cable bolts. Make sure all is free of rust/contaminant that could hinder a good contact.

Step 2A: Simple If you have a trickle-charge auto battery charger, use it to charge the battery overnight. I have a Schumacher battery charger at home, bought it for $40, and it's been proven to worth many times its price.

Step 2B: Pain in the butt If you don't have a battery charger, remove the battery from your car and drive it to Walmart and let them do a battery load test. If it passes, great, pick up a battery charger and get to work, or let them do it about $2.50 according to their website. If not, go down the aisle and pick up another battery. Do worry about Walmart brand, they're made by the same clowns who make the name brands.

Hopefully, that's it. Batteries are consumables, don't sweat too much over them. Now alternators, that's a bigger pain. Let me know if you need a recommendation on a good one. Good luck.

http://www.walmart.com/cp/Battery-an...ervices/495846

 

Not that I need one, but always interested in hearing what/where regrading replacement parts.

Good write up. Only thing to maybe add would be to clean the field winding (aka exciter) plug connections on the alt and smear the prongs with silicon grease.

P.

 

As an aside for replacing alternators, what constitues an 85E vs a 85? I guess it has to do with date of manufacter but what is the cutoff date that determines wether it's an 85e or not?

 

Just something to keep in mind, although you bought the battery 2 years ago, it may have been sitting on the shelf for just as long before you purchased it.

 

Thanks for the info guys.
Save the wave!

 

If anyone else is looking for a quality replacement alternator, look no further than here:

http://www.alternatorparts.com./CS-1...cial_offer.htm

I got a CS-144 from them in '05, to replace the replacement of my replacement factory CS-130-piece-of-crap alternator. Still with me?

As you know, the engine heat does a number on alternators (among other things) so being able to withstand and dissipate heat is critical. I can honestly say the alternators built by these guys are top notch.

Being a 24-years-old plastic-encased-bucket-of-loose parts, my car have had it's shares of unexplained electrical gremlins discovered and fixed. Plus some component showing its age yet still not kicking the bucket... which explains my varying electrical consumption issues. Getting a bigger output/heavier duty alternator fixed that. Not to mention saving a bundle just because I've not had to replace it, YET. I did had to have a local alternator shop rebuild the bearings and such ONLY because my bad belt tensioner caused the belt to move at an angle.

So if you've not had the workmanship of a local alternator shop, then consider ordering online from these guys in Michigan.