chadman

I'm having charging problems with my car, I have tried two regulators, a new electronic one on now. Also two different alternators, currently running a new 100 amp. The regulators don't seem to operate properly, at idle with the spal fans running I show full discharge on the gauge, at cruise speed I show full charge. Never anywhere near the middle of the gauge. Driving in the city, the battery slowly runs down due to excessive discharge time. Anyone have any idea what I can do to remedy the situation, could it be a grounding problem. I understand that at idle the load is probably greater than the alt can produce, but I think the discharge with the fans is excessive. HELP! :confused: :confused:

67's

I would ask if you have done anything recently to the car new radio, elecric fans,etc, did you have the problem before? Maybee if you added something it might be overloading the system.

Sorry I can't help, you should buy a voltometer to check where the drian is comming from.

Tom

73Ken73

How old is the battery?

chadman

The battery is new, I have added electric fans and I understand they are about 20amp load. No radio, a/c or any other electric access. The battery doesn't go down when the car is not used. It just doesn't charge enough to keep it from draining with the fans running cycling. I know many cars have electric fans and don't have this problem. With the 100amp alternator, it seems it should have plenty of capacity. I have always had the problem but the elect fans have made it more obvious. I have just had the car about a year.

couldbefun

Okay well heres my 2 bits. i work at a electricians's shop as a journeyman apprentice. now i also do some work on the vehicles here. the only suggestions that i have are 1. check your wiring with a diagram from kelty's or something. if you have the alternator wired wrong, there are some old designs that i BELIEVE will drain the battery if the polarity is reversed, acting like an electric motor draining your battery. this seems highly unlikely though. my suggestion is to 1. remove the alternator or remove the belt
2. go for a drive with a buddy trailering you in case you need a lift. you probably will. before you do this, have the battery fully charged. record the time it takes to drain it if it is losing juice this fast. if the time it takes to drain it is longer when the alt. is NOT hooked up, then you have a problem spanning throught the belt to the alt to the battery. if it takes longer to kill the battery when the alt is hooked up, then the alt is at least helping a little. in this case i would suspect a bad ground that is zapping the juice away from the alternator. now this is a pain in the A** to test it this way, but i have no other suggestions as that i have never seen anything like that. if its to this point, my mechanic gets a call first thing in the morning. :lol: i am sorry i could not be of more service, and remember this is a wild shot in the dark thing. it may not prove anything. if you havent already, just take teh car down to a chevrolet mechanic, give him 100$ and say see what you can do. justa sk him to look at it. this is definitely worth it to save you from grieving over your baby

Ingar, Norway

chadman:
An 100A alternator should have no problems keeping the system charged. Something is wrong with either the alternator itself, the regulator or wiring.
Typical problems with regulators are to low regulated voltage (should be 14.4V) or weak regulation. (Doesn't drive the alternator properly at high loads, this will always be the case for internally sensing regulators. On my 1980 the sensing point is at the starter which is a good solution.)

To diagnose, measure the voltage at the alternator, starter and battery at idle with fans running. This should tell something.

You can short the regulator to test the max capacity of the alternator. The 1980 has a alternator has a test hole that can be grounded to do this.

I've written article "Understanding the alternator" at my page. The 1980 shop manual electrical section is also at my page.

mrvette

You need a Digital Voltmeter (DVM) hooked up at the alt and then at the battery, all fans off, see that 14.8 is max charge voltage at 2500 rpm/s at crankshaft...tach reading in other words....see that it stays there pretty much with engine at idle.....if not, you have a lazy regulator...if it does, turn on the heater-a/c blower full blast...see if it stops charging...still should read around 13.9 or so.....now turn on the cooling fans, one at a time....then both of them....the current drain of fan starting should make engine stumble a bit...they draw about 30=40 amps on startup...20 on run... or pretty close....and thost figgers are for each motor...

check voltage at alt, and bat....should now vary more than .3 volts at most...
check all connections, engine to frame, frame to battery, battery positive to starter....these are all checked by measuring voltage drops across each connection...so positioning of the voltmeter leads is critical as to accuracy of readings....
IMO...I think you will find corrosion everywhere, and maybe some bad connectors...

GENE

GENE

john73bb

I had a problem like this on my car once. I had inserted the connector into the alternator backwards. Wouldn't charge, and made the gauge do wierd things. It's worth checking.