New Alt, Batt Light On!

I installed a new Tensioner and Alternator. Had the Battery disconnected for the job, installed everything filled her up with new antifreeze and while I was bleeding the radiator I noticed the battery light on. I checked voltage coming out of the alternator. 14.9v steady! I have not checked the thermistor yet. What could I have done?

Was told 14.9 is too much and the regulator was bad in the new alt.

Check that you plugged in the 3-prong plug on the back of the alternator.

14.9 volts is fine under certain conditions. If the regulator was bad, you'd likely see over 17 volts, and a corresponding system voltage code (SES lamp).

Connection was surely plugged in. Advanced ordered me another one. Will update when new one comes in.

Hope it works out. The battery light comes on when the alternator isn't charging the battery. At 14.9 volts, it's obviously charging. Maybe use an amp meter to see how much current it's putting out. Most autoparts stores will do a free alternator check, which determines the number of amps the unit can produce.

We didn't talk of amps. Got the new one in today and all is well. Voltage is at 13.8. What should my Amps be?

140 at least. Mine's a 150 amp from NAPA. Can't have too many amps, but very high amp ratings can mean shorter life for the alternator. Not something you need to measure, but if you notice dimming of the headlights when accessories are on, it might mean your alt is not able to put out enough.

If your thermistor is working correctly, you will notice the charging voltage will change from about 12.9v to 14.9v depending on the temperature of the battery and environment. I have an on-board volt gauge, so I notice it more than I used to. Most of the time, it's close to 13.8v.

No dimming at all! Seems to be working fine. Thanks for the info!

Second one was bad as well. Worked for a day then set the light off again. Ordered from the GM dealer!

I had a similar experience, tried 2 units before one worked.

Got alternator in from GM. Wrong one! WTF! Kinda pissed but everything is gonna be alright. I write this to lower my blood pressure!

rivparadise wrote:

Got alternator in from GM. Wrong one! WTF! Kinda pissed but everything is gonna be alright. I write this to lower my blood pressure!

was it the wrong model entirely or does it just need to be reclocked? (clocked = remove case bolts and remount 90 or 180 degrees rotated so the mount fits). I suspect they got you the one for the 99 though (diff case entirely).

I think it was one from a 3100. Had no fins on pulley, only two mounting bolts, no 10mm threading on the back as well as the clip wouldn't fit! They somehow had another one for me by 230 the next afternoon! Works just fines however, I do see a brightness change in my headlights under heavy throttle and also when I start the car it seems my interior lights get bright for a second then go to normal, almost like a mild surge.

Consider cleaning the battery terminals and the main ground by the battery, under the rear seat. Also take into account the age and condition of your battery. If it is under 450 CCAs as measured by a commercial battery tester it's time for a replacement.

Battery was new from GM in March and EVERY GROUND ON THE CAR was cleaned or replaced as needed! I had a nightmare with the grounds for over a year prior!

OK, next thing to do is test the battery - probably enough to use a voltmeter to check voltage (other factors will follow) Assuming it's the proper Group 79 battery and if the battery measures more than say 12.2 volts in-circuit with the car off then it should be OK. Under 12V and wither there is an extra drain somewhere or battery might have issues (might not be charging when car is running, time to check thermistor on + cable).

What I am doing is eliminating causes for the lights flaring under heavy throttle.

Right now I am thinking nothing is likely amiss, but rather that you drive mostly short trips and the battery charges well but not fully, and I am thinking you use the delayed exit feature of the headlights and they stay on for a while when you park. Which also tends to drain battery. Consequently when the engine is revved the voltage regulator lets the alt crank out a lot more power and the lights flare a little. A tell-tale of this is it'll do it (flare when revved) after short drives but not after longer ones say 90 minutes or more..

I also did not ask what extra electrical accessories you may have installed.

so... what else can you tell me?

Albertj

That makes sense due to alot of short trips. Thermistor is fine. I checked battery and voltage is good. I have no other electrical accessories installed. She's getting packed away for winter in a few weeks and every thing else seems to be running awesome so I won't worry about this. I was going to put her up on blocks, pull the battery and dump some Sta-Bil in the gas tank and cover her.

rivparadise wrote:

That makes sense due to alot of short trips. Thermistor is fine. I checked battery and voltage is good. I have no other electrical accessories installed. She's getting packed away for winter in a few weeks and every thing else seems to be running awesome so I won't worry about this. I was going to put her up on blocks, pull the battery and dump some Sta-Bil in the gas tank and cover her.

OK

in practice the problem will decrease or go away if you minimize the Key Off headlight delay. But short trips are short trips and the Riv battery is big, as well as the parasitic "off" load is substantial - so takes a while to charge fully.

Thanks Albert! Anything else I should consider in storing her away? Heard some people leave battery in car disconnected. I was going to bring mine in the house. Others said take the belts off of the pulleys! It's not heated where I'm storing it.

Here in Michigan Sea-Foam has become the fuel stabilizer of choice in my area. I have many customers tell me that their vehicles or boats or whatever start and run like the day they put it in storage. With Sta-Bil, they had issues every spring.

rivparadise wrote:

Thanks Albert! Anything else I should consider in storing her away? Heard some people leave battery in car disconnected. I was going to bring mine in the house. Others said take the belts off of the pulleys! It's not heated where I'm storing it.

Consider starting it every couple weeks.

Stabil does not work right unless mixed well in the fuel. Seafoam mixes better without as much agitation I am told.

I use StaBil in my gas cans and classics that don't see much road time (MG), I always put the stabil in before the gas and I've never had a problem. I put the mower and snowblower away with whatever gas they had (because I always have stabil in my gas can), and I can put the MG away at any time. I've never ever had a problem with my small engines or the MG starting next season.

Apparently the fuel nozzle from the gas station is enough agitiation!

deekster_caddy wrote:

I use StaBil in my gas cans and classics that don't see much road time (MG), I always put the stabil in before the gas and I've never had a problem. I put the mower and snowblower away with whatever gas they had (because I always have stabil in my gas can), and I can put the MG away at any time. I've never ever had a problem with my small engines or the MG starting next season.

Apparently the fuel nozzle from the gas station is enough agitiation!

If you put the StaBil in first then fill (like the label says) it mixes no problem.

If you add it as an afterthought it does not.

Albertj