Battery??? Alternator???

[w8n4ya]

Ok...here's my story, I'll tell it like it happened because I don't know what could be the cause and if any or all of it is relative.

I have a 1990 with 106,000 miles. Last night while driving home, I plugged in my cell phone charger in my ash tray. After a good while of highway driving (maybe 15-20 miles), my cruise control suddenly disengaged and would not go back on. Then the SERVICE ABS light on the DIC came on. Within 10-15 miles, my dashboard lights became noticibly dim. I started to feel a loss of power in the engine and began to hear popping noises from the exhaust (like I was running out of gas) only with a full tank. I looked at the voltmeter and the needle was pointing at the 1 o'clock position within the "8 volts" of the cross-hatched area. The car shortly died as I glided to the right hand side of the freeway before being stranded.

Once on the roadside, I tried to restart. The engine actually cranked but then CLICK*CLICK*CLICK. The interior lights were at fully power, as was the radio. I did not have enough power to raise the headlights though. I activated the HAZARDS until the tow truck operator arrived, which by then were almost completely out.

We arrived at my house just 3 miles away and my interior lights were back on to full power...inspite of what I thought was a battery drain with the hazard lights constantly on. The following morning, the lights were full poer and I tried another start up with the same results...crank*CLICK*CLICK*CLICK.

I need the expert advice of all those who have gone through this or at least a similar instance. Thank you all very much in advance.

[GeorgeT]

I would begin by checking the negative battery cable and ground connections. I have had one leg of a multipart negative cable on a Buick go bad with similar results - car stopped, after a while it restarted and ran okay but without A/C and a few other accessories.

[w8n4ya]

Well, I was able to find my problem and apply the solution.

I picked up a battery, an alternator, a serpentine belt and a belt tensioner tool--just in case on the way home from work today.
First I replaced the alternator and the serpentine belt. Got in and tried to start her up...crank*CLICK*CLICK*CLICK. No result.

Then I replaced the battery, crossed my fingers and...VROOOM! The car started right up. I checked the gauges and everything is reading normal. I guess I had a bad alternator, which drained and caused a bad battery. I changed the belt just as a precaution. All within three (3) hours in the parking lot trying to beat the sunset (I live in a condo with no garage). I'm thankful I had all the previous posts on this board to rely on, and of course my GM shop manual. Not to mention I've started a pretty good tool collection

Thank you for your help and support...and proving that forums such as this are invaluable to our enjoyment of our Corvettes.

[c4cruiser]

Did you have the alternator tested? Alternators on C4's are prone to failure from extreme heat under the hood. 8 volts sounds like an alternator failure and that's not enough to get the coil energized to provide sufficient spark. Did you see voltage drops early on? Something like 12.8 volts or down to about 11 before the car started to run bad?

Did you get the battery charged up before replacing it? A good charge may have saved the battery instead of having to buy one. But it sounds like you got the problem solved.

[Vettefan87]

Does the car even use the battery after the car is started? I always thought after that the alternator was doing all of the work and the battery was just being charged.

[Grizzly]

Originally Posted by Vettefan87

Does the car even use the battery after the car is started? I always thought after that the alternator was doing all of the work and the battery was just being charged.

A car will run with the alternator disconected but not the battery. My 59 Impala runs a good while on the battery (gen's not working). It helps that all it has to do is generate a little spark. The battery is the buffer in the electrical system. For instance it takes about 200-250 amps to run a starter. After that current is drawn out the gen/alt replaces it at a much slower rate.

I have noticed that some newer cars can not be jumped imediately after hooking up the cables if the battery is dead flat. I guess there has to be some minimum voltage in the battery before the modern electronics will work.

[Edmond]

Glad you fixed the problem. Same thing happened to me a couple years ago but I was fortunate enough to have the car go out as I pulled up into my driveway.

I tried to take the cheap way out with a used alternator. It failed a few months later and I ended up getting a new Delco unit. About a year before that, I replaced the battery with a Delco.

It's a very straight forward job. Glad you got so much done. Feels good doesn't it?

[c4cruiser]

Originally Posted by Grizzly

A car will run with the alternator disconected but not the battery.

Older cars should run with the battery disconnected. Years ago when alternators were just starting to be installed in cars, Chrysler did a test with one of their compact cars with an alternator where they started the car, disconnected the positive cable from the battery and drove the car almost 200 miles.

This was a car with a simple points-style distributor and a coil so there were no fuel injectors, electric fuel pump, computers and such. The alternator will provide sufficient voltage to keep the coil energized for awhile. Without a battery in the circuit, there was no way for excess charging current to be "stored" or bled off. This condition will usually ruin the internal parts of an alternator but as a test, it was an impressive display to people who had been used to generators in their cars.

I remember driving at night in cars with generators where the headlights would dim as the engine speed went to idle and as soon as the RPM's kicked back up, the lights would get brighter. The generator did not have tha ability to provide sufficient voltage at low speeds and when the current load was high.