Tedd Thompson

On the way to town today I noticed the amp meter was pegged at 30 + amps. I kept an eye on it thinking that the battery might be low as I worked on the hydraulics adjusting the convertible top.I had had it up and down a bunch of times with out starting the car. Twenty miles later and it still read 30+ amps. I disconnected the generator hot lead and ran home on the battery. This is the third time this has happened in the last three years.Each time I thought I had it figured out it would happen all over again . I have replaced the generator/ regulator one time, just the regulator once and the battery another. Acts as though the regulator thinks there is a need to charge the battery, but the battery shows 13.8 volts I thumped the regulator trying get it to unstuck, but no luck. Any Ideas. It has to be something simple that I'm over looking.... Tedd

PS. this ts on my 1955 Olds all stock.

MN71W30

If you drained the battery running the top up and down it may have needed the continious 30 amp charge for a while. I would try to confirm the accuracy of your gauge. Maybe it's off?

Tedd Thompson

That's about 40 minutes at 30 amps. I would think it would be at full charge. In fact my volt meter showed 13.8 volts in the battery. Is there something that could cause multiple regulators to become faulty? There have been a total of four regulators counting the one that was put in on the original build. The old one could have been alright Just old so I changed it out with a new rebuilt generator. I did have a bad battery that would only hold about 10 volts and this may have caused one generator/ regulator to give it up but not two more. Any more thoughts. I hate to keep throwing parts in with out knowing what the problem is. ..Tedd

6inarow

Tedd, have you checked all your grounds? I have chased so many electrical problems to a bad ground. This might have nothing to do with your situation but it never hurts to check.

z11375ss

Doesn't an amp gauge run on resistance? I had one go bad and couldn't figure it out. Had to hotwire the car to start it. Couldn't they lead to a car fire? I think a volt gauge is what you need to have. Am I right?

MN71W30

The old car DC amperages were measured in series. I've had more than one old Chevelle with the amp gauge burned out. They were dangerous. Personally I believe a voltmeter is good enough. It seems to me a battery can only draw what it needs. I don't think you can charge 30 amps into a charged battery. Something doesn't add up. I would have the battery tested and start from there. Is it an old acid type battery?

Tedd Thompson

The amp meter is in the dash group ,the volts I measure from my muli meter hand held unit. I will look over the grounds today. The battery is new acid sealed type with a glass window. The amp meter drops in amps when RPMs drop like always but will climb to 30 amps at anything over a fast idle. It works like normal,just won't shut down as it should when the battery is full. I can turn on all electrical devices and the amps stay at 30. I have hooked up my battery charger to see if perhaps the battery will take more than 13.8 volts and the regulator is not shutting off soon enough . This seems like a shot in the dark but what the hell nothing to loose.Is there a way to adjust a voltage regulator or are they good or bad...Tedd

citcapp

Tedd,

My "Motors repair manual Date 1967" has not less than 5-pages on generator and voltage regulator testing. Looks like a tough show if you don't have a background in servicing these units. If it were mine I would find a good auto electric shop and get a price on testing and correcting the issue.

Rickman48

Can't remember what car it was, know it was an older G.M. but when it did that, I hit the horn and the gauge went back to normal. A few times, and never happened again.
I'm not sure, but is the horn relay somehow in series??

greenslade

does every thing else on the car work ok,lights heater fan wipers ect.if the battery is overcharging it will heat up [be warm/hot to the touch]when charging.if is keeps overcharging it will start to boil and smell like rotten eggs and start to put acid out the vent hole.if it does boil be very careful with it the vapour is very explosive.

Tedd Thompson

greenslade, lights, heater, radio , horn all work fine. The wipers are vacuum and do not apply. If I don't find something out today I'm putting a new regulator in tomorrow. my biggest concern is why has this happened so many times ? Back in the day when I drove these type cars I can't ever remember replacing a regulator. Generators, yes, never a regulator. Maybe parts aren't what they once were.Didn't see made in China anywhere but I didn't look much either. time will tell....Tedd

PS thanks all for your impute

Lady72nRob71

This sounds like a dangerous condition, if the ammeter is telling the truth. Most older ammeters operate off inductance, the magnetism caused by current flowing through a conductor. Therefore, these tend to read less than actual as they age. However, anything is possible. You could get a cheapo ammeter to hook up temporarly to the alternator to verify. (I got one from harbor freight for 5 bucks for this purpose).

After this >30A condition occures for a few minutes, feel the big red wire from the alternator. If that much current was really flowing through it, it will be a bit warm to the touch - maybe hot.

Seems that your voltage is correct. If it stays between 13.2 and 14.5 during those current spikes, then the regulator should be fine. Of course if the short is enough to exceed the output of the alt, then it will drop more.

You can pull all the fuses to see if there may be a short in an accessory circuit, but I am doubting it. Would be good to check though.

If the battery had an internal short (the one on my 86 did this), then it would become quite warm. Of couse if the battery shorted, then it would most likely not restart the car...
In fact that much current over a long time will make it become hot up to the danger point. How old is the battery?

Just rambling off some related thoughts... Hope you find the problem.

Tedd Thompson

Lad72ynrob71, Battery is new this spring,but this is what happened to cause the old battery to fail.I had no problems for six months then this again. If the car was just around town car I wouldn't worry about it as much but we often take trips of 800 to 1000 miles and I don't want to be worrying about this issue so far from home. Thanks for your imput... Tedd

MN71W30

Hook up a big battery charger and see if it draws a continious 30 amps with the motor off. It should read only a few amps when fully charged. I have heard that warmer climates are harder on batteries than colder regions. I'm betting on a defective battery. It happens.

Oldsguy

I think Rob has a point about pulling the fuses, I would say specifically the fuse for the gauge panel. I don't think the amp meter is directly wired without a fuse. I was thinking that the meter itself may be failing. If it is truly a D'arsonval type meter movement then it could be sticking but there would have to be a temporary condition to peg it at 30 amps. I have seen them do this. That would mean the fuse for the gauge cluster would have to be a 30 amp fuse at least. Hmmm, a wiring diagram for you car would verify this for sure.

Tedd Thompson

Replaced voltage regulator, problem solved......for today.I have 0 confidence in this fix. If I have any problems at all I'll put it in the shop. I know a great auto electrician in my area that I trust and who likes old cars. I'll be in touch if this problem happens again. Thanks all for your advice and suggestions....Tedd

MDchanic

To flow 30A into a 12V battery, you would need a significant voltage (15 to 16, I'm guessing), unless the battery was very discharged.

If you're generator's running at 13.8V (low-normal), you should NOT be able to put 30A into a charged battery.

Possibilities:

• Bad gauge (try an old hot rod gauge from the tool box in series with the Gen output).
• Bad Battery (internally shorted, so with low resistance and voltage. It should be misbehaving, and probably show less than 12V when disconnected from the car).
• Current's going somewhere else - Dangerous at 30A! (check things like the cigarette lighter, pull fuses, check circuits for current flow with an ammeter).

I'm not sure how a bad regulator could push that much current into a good, charged battery at only 13.8V, so I don't know what to sat about that.

Good luck!

- Eric

citcapp

Tedd,

you have replaced the regulator before to fix this problem and it hasn't lasted as a fix in the past. I believe you have a minor short in a winding of the generator. I suggest you take it out of the car and have it tested by the auto electrician that you know