I had been gone from my car for about 6 months which was working fine when I left and fine for the person driving it until about 1-2 months ago. It started out as seeming to charge low on the gauge, around 11.4-12.4, with a/c and headlights on at idle at its worst. This is on hot Florida days and now hot California days. Now nice and cool at startup and driving at night and sometimes during the heat of the day, fully loaded, it would indicate high 13's to low 14's. What is weird to me about this is that when measuring at the battery at the lower voltage ranges of the gauge indicating 11's and 12's it is showing me about a 1 volt drop between multimeter on battery and the gauge in the car. However, when it is showing high 13's and low 14's on the gauge in the car it is only about .2 to .3 volt drop.

The thing is, it is very random at times it does this. So even at lower voltage of the 11's it is actually charging fairly alright, but not great and obviously when its reading high 13's and above its doing great like it should.

I'm in need of some help on what is causing this so I can get it fixed ASAP. I feel I might need a new alternator as at one point I got a new (remanufactured) one and it fixed the problem until it crapped out a few days later. So I put the old one back on as I had to move and am now at a point where I can finally solve this issue.

Battery is brand new along with all the wires looking to be in good condition. I have not checked the ground strap on the engine block yet but it is on the list to do.

The car is a 1989 corvette with stock electrical system except a highly modified sound system with I haven't been using since I had this problem appear.

Please let me know your inputs on what I should do and check as I really need to get this fixed.

Thanks.

 

I believe that there's no substitute for a quality "load test" done with a carbon-pile quality device. You mention intermittent/random and a proper test would eliminate the "sometimes" I believe.

What you do before hand is confirm the alternator ground and maybe add, you clean the grounds related to the charging system that you mention haven't been done and then you find a shop that can do the test OR you buy/borrow/rent a "carbon-pile" load tester and do the evaluation yourself.

 

I too a look at the grounds and everything looked surprisingly clean. I may need a new alternator bracket bolt, the upper one, as it looked fairly rough and not cleanable. I had a test done at a local place for free. Not sure if it was a carbon pile tester but it showed up as a bad voltage regulator in the alternator and a weak battery most likely resulting from the alternator in what they've seen before.

I think I will order a NEW alternator probably a remy or Ac delco from rock auto as it is only about $100. Also does anyone know where a good place to get the upper bolt from online? I'm new to the area and don't know where much is.

Any tips on what I have found or suggestions please let me know.

Also anyone know any good engine rebuilders and/or general mechanics shops around Fairfield-Sacramento area?

Thanks.

 

Home Depot has a pretty good assortment of metric bolts. That bolt is very close to SAE size, but don't make that mistake!

 

What type of a facility checked yours? Check was done on the car or you carried it in? Do you know if what you have now is already a "reman" or do you suspect original?

The "local" checked it for free - why wouldn't you buy from the "local"?

I don't get it! I really don't

 

Just a local shop but they said all they had were remanufactured ones. I want a new one not remanufactured. Plus I had a once over of the car done for a few bucks. The current alternator is pushing 10 years or more. Check was done on the car. Maybe I will go back and see if they will order a new one and let them put it on

 

So your current one then is known to be already a "reman" from someone? You mentioned a reman failing and putting old on.

You mention a modified sound system. Was the charging system modified along with the install or have you attempted to do it using just the '89 wiring? Maybe it's time to just "clean up" the install and the entire charging system. Maybe a CS144 or just a upgraded CS130.

 

The only modification made to the charging system was a replacement of the red power wire that was old and beat up with a new better wire. Otherwise it is all stock but has worked perfectly for the last 2 years. But you have more experience and know more than me about this part of the car and I will take in your advice on doing some upgrades to the system

If you could give me some info about the main things to be done that would be great and from there ill go on about how to do it myself

You've been a great help and i really appreciate it.

Thanks

 

I consider myself to have "NO EXPERIENCE" when audio upgrades enter into the mix. I have opinions BUT ...

I'd gather a list of all components and maybe wander over to the AUDIO section THEN READ using maybe the search for similar/same components. Once you feel you've got a "grip" on the subject post your own thread listing components and inquiring as to the electrical/charging system requirements etc.

https://www.corvetteforum.com/forums...lectronics-20/

 

Thanks all for the help. While having a bad alternator, I got a new one and it fixed the erratic charging issue. With A/C and headlights on with radio blasting it charges at 13.4 minimum at the battery idling and closer to 14 when driving around and stays at almost a constant 14 with everything off.

However I have not been able to find the issue of it reading a 1 volt difference from the battery to the gauge. Everything checks out good, grounds and positive cables. Did not check at the starter to see about those ends of the cable due to time constraints and will be doing that shortly. Only other opinions on it I have seen are possibly loose connections at the connector to the dash or a bad wire in there which may be a while before I check.

So for now thanks for the help and I have some other questions I will post in a new thread.