billschroeder5842

I have a perplexing situation with my charging system on the '89.

Under brisk acceleration and when the RPM hits about 4000 rpms, the red "Battery" symbol flashes on the DIC. The symbol never comes on any other time accept 1) ignition forward/pre start 2) under higher rpms.

I've watched the digital volt meter on the dash when the battery light comes on. It is anywhere between 14.4-14.6.

I've read in the FSM that the DIC battery light comes on when there is a low or high voltage reading; basically when something is not in spec

Is my voltage regulator dealing (or not in this case) with an "over charging" situation or it is something else? Is there anything i can test on the car or will I need to take it in/swap it out?

Thanks!

84 4+3

I'm not 100 percent sure on the charging system on these as mine is a bit older and everything else I've worked on is newer... In my truck however, when the alternator started going, the symptoms were it kicking out when it would down shift to pass or accelerating over 3000 rpms. Eventually it just stopped charging. Now on the 84, it was the opposite. If I pulled it out of the garage after sitting a while it wouldn't charge until you hit around 4k. My regulator was dying and I guess the high rpms excited it or something. The fan coming on high and the headlights being on used to pull down the voltage with that iffy regulator. I've also found that the dash reads about half a volt lower (on mine) then at the battery or alternator. If I had to guess you could be experiencing an overcharging situation like you had said.

JimLentz

First verify the digital reading with a know good multimeter. My digital voltage reading is about .4 volts high of actual voltage. What is your reading at lower RPMs?

dizwiz24

When batteries overcharge they can produce explosive hydrogen gas

WVZR-1

The lamp is "driven by a lamp driver" so I'd think you just monitor the alternator output with known good meter for an indeterminate amount of time to confirm alternator output. It's maybe not an alternator VR issue but driver issue. If you confirm a charging issue THEN you throw parts at it!!

A 27+ year old car maybe just a wiring degradation issue that throwing parts at it won't fix.

Maybe you ask Bryan about the "driver"!

pcolt94

How old is the battery? Does it hold a good charge on it if car sits for 4 0r 5 days?

I agree to use a DVM for a true reading. Run a wire from the battery to inside the car and find a ground. Then you can monitor the voltage real time.

Did you check the connections (& grounds) on the battery and alternator for tightness. Look for any corrosion on them and major grounds. (Just a thought)

billschroeder5842

Thanks everyone- the battery is about 4 months old and hold charge no problem. I drive the car about 3-4 days a week (damn near a DD!) so it remains pretty charged.

The alternator is a reman that the previous owner (I got the car in June) put on abut 5 years ago.

I'll put a multi meter on it and get a "true" reading as compared to the dash reading.

billschroeder5842

Well, I just checked mine and my experience is similar to yours Jim.

At idle, my multi meter measure 14.8/14.9 and dash shows 14.6/14.7

xrav22

That seems on the high side I have reached 14.2 max before.

84 4+3

May be a regulator issue. I mean I guess it is also possible an undersized pulley was installed but the regulator should compensate until it is over spun... If you feel like pulling it out the local auto parts store should be able to test it for free then you'd know for sure. On the bright side the rebuild kits are rather inexpensive if it comes to that.

pcolt94

On first start of the day I get the same numbers on the dash readout. But after 1/2 + hour driving the voltage should come down. I will get down to 14.1 or 2 by the time I get home or destination as it gets to full charge.

fake

Belt slipping check for cracks with a magnifing glass or check for oil or anti freeze on belt Good luck!

JimLentz

If those readings are after the car has run for a while they are too high. By the time I get to work my voltage is around 13.8, although my gauge reads 14.2 volts. Sounds like a problem with the regulator.

ctmccloskey

Hello out there,
If you get a warning light about the charging system what I like to do is put my Fluke Multi meter in the car with it monitoring the voltage in the "Min-Max" mode. (Get the power right from the battery so you do not have a voltage drops going through the wiring of the car, this means no cigarette lighter voltage or dashboard readings.) This allows me to watch how low the battery voltage goes during starting and running of the car. The other side of the data shows just how high the voltage goes. Being cold outside the set-points might have changed due to temperature compensation for the battery The battery connections should also be cleaned if questionable.

Before going too far I would take the multi-meter and check to be sure that you do not have AC ripple voltage coming out of the alternator. This is actually more common than most people think. This can toast your ECM and any other electronics in the car if left unattended.

When a battery is fully charged the alternator should go as high as the set-points allow (~14.5-14.8 Vdc) and then ramp down the voltage back to the mid 13's and stay there just topping off the battery. If the voltage stays up above 14.5 very long then either the battery or the alternator are having issues.

Take the battery and isolate it from the car and then charge it up "completely". Then re-install it in the car and test it again. If you are not sure about the age take to someplace and let them verify that the capacity is still there.

I don't know the age or brand of the battery you are using but you might want to consider a new one if the current one is more than three years old or has been left discharged for any period.

If you are using one of the OPTIMA Tubular batteries then you are on your own. The optima batteries have some unique characteristics that are not well known in the automobile world. They require a special charging system that charges through a second battery. I believe that they do it to keep the incoming charge free of any spikes and/or noise.

I have tried a couple of OPTIMA batteries and neither lasted more than 18 months in "Standard" or "typical" automobile applications. I used one in my Pick-up and the other in a Cadillac STS. The last one (STS) lost capacity and was unable to start my V8. So I removed it and started charging the battery when it released a cloud of very foul smelling fumes and started to smoke like it was ready to start fire. I continue to use my old favorite "INTERSTATE" batteries and have had much better luck with all my vehicles.

With the number of types of cells out there today for Starting & Ignition applications for automobiles it is harder to give advice without more information regarding the battery type. I still like Flooded Lead Acid (FLA) batteries the very best. They take a licking and keep on kicking.

I suspect the original poster probably has a bad battery causing the higher than normal charging voltages. Verify the voltages, check the alternator and have the battery's capacity verified.

I wish you all a very Merry Christmas and an awesome New Year enjoying your Corvette!!