Amp guage fluctuation

[Al R.]

I just installed a new battery and halogen headlights so my old eyes can see where I'm going at night in my 59. Now the amp guage bounces around a little, not a lot, though. The car has just been put back to use after a 2 month nap. Any suggestions? New cable ends have been installed at the battery. Also with the lights on, you have to rev to approx 900-950 rpms for the generator to charge. Volt reg or gen ?? Al

[Chuck S.]

Re: Amp guage fluctuation

I would double check the connections at/around the headlights and make sure they are all tight and secure.

A friend once had an erratic ammeter accompanied by severe electrical headaches (dead battery, flickering headlights, etc), and he asked me to help him find the problem. I looked under the hood and...duh, everything seemed OK.

I was about to tell him he needed professional help, when I noticed one of his left sealed beams was shattered and the center element was hanging loose. On a hunch, I had him get in the car and watch the ammeter while I bumped the element around. Sure enough, every time that center element bounced and grounded to the retainer, sparks flew and the ammeter went bananas.

What an easy fix; because he ignored a simple maintenance issue, he was about to have an expensive maintenance problem. It's probably not as simple in your case...you should have noticed flickering in your new halogens if those connections are loose. But you may have disturbed something else during the installation that's now making an intermittent short.

Or...It could be that those bright halogens are just pulling more current. If you are at a low charging rate, the generator output may not fully cover the extra draw, and the difference is coming off the battery. The regulator will be constantly calling for the battery to be recharged. I thought generators didn't charge until high idle speeds anyway, and that's why they went to alternators.

[Terry M.]

Re: Amp guage fluctuation

Or...It could be that those bright halogens are just pulling more current. If you are at a low charging rate, the generator output may not fully cover the extra draw, and the difference is coming off the battery. The regulator will be constantly calling for the battery to be recharged. I thought generators didn't charge until high idle speeds anyway, and that's why they went to alternators.

Chuck, I vote for this explanation you provided.

Check the temperature of the wires feeding the headlights while they (the headlights) are on. Just put your hand on them while someone revs the engine. There is no free lunch with electricity (well almost). If the lights are brighter they use more voltage or more current or both. They may need a larger wire, or an auxiliary relay to feed them. I can tell you how to install the later, but it won't pass NCRS judging -- but then neither will the halogens.

It is too long a story to entirely go into here, but a common modification for the 1994 to 1996 Caprice/Impala headlamps is to add an auxiliary relay. This increases the voltage to the bulb (OEM wire size and length is an issue) and makes the bulbs glow white instead of yellow. This is popular enough that folks make a plug and play harness for those cars. A similar harness could be made for your Corvette.

[Dan D.]

Re: Amp guage fluctuation

Al, I believe the halogens are your problem (per the previous posts). They draw more current than the T3s, and there have been previous posts on this forum about this. These are the problems and effects other people have reported:

1. The old generator is only rated at 30 amps( actually 1962 cars are rated at 35 amps). But the system cannot supply enough current to run halogens until you rev the engine, and then that is marginal at best and explains the meter fluctuations you are seeing.
2. Old wiring cannot handle this current and the wires may exhibit heating.
3. The headlight switch cannot handle the extra current either. Past reports on this forum indicate some users have found that the circuit breaker that is built into the headlight switch will toggle on and off.
4. Other reports of a hot dash above the headlight switch have been noted.
5. If you have old wires and old headlight switch, some corrosion in the headlight switch and wiring is most likely, which aggravates the problem.

As previously mentioned, a relay will fix the heating and headlight switch problem, but it will not fix the generator problem. You are only over stressing an old generator and increasing the possibility of generator failure.

These cars were not designed for halogen lights. My advice to you is to put the T3s back in it. I know, my old eyes do not work too good any more either. Welcome to the aging process. -Dan-

p.s. I don't know why they call these the "golden years". There is nothing 'golden' about them.

[Terry M.]

Re: Amp guage fluctuation

p.s. I don't know why they call these the "golden years". There is nothing 'golden' about them.

I beg to differ. I think these ARE my golden years. These years are not better nor worse than my younger years, they are just different. I wish I could say I was astute enough to plan for my retirement years, but that is not the case. Yes I did some planning, but I got real lucky. As the Rev. Mike says: "It is better to be lucky than good."

[Al R.]

Re: Amp guage fluctuation

I failed to mention that the fluctuation occurs with the lights off also. I will try charging the battery to a full charge tonight, & if that doesn't correct it, I'll probably contact ya'll about the relay or try to find new non-halli bulbs. I'll let you know how it goes. I'll recheck all connections, also. Thanks! Al

[Robert J.]

Re: Amp guage fluctuation

I failed to mention that the fluctuation occurs with the lights off also. I will try charging the battery to a full charge tonight, & if that doesn't correct it, I'll probably contact ya'll about the relay or try to find new non-halli bulbs. I'll let you know how it goes. I'll recheck all connections, also. Thanks! Al

Check your ground connections....bob

[David Z.]

Re: Amp guage fluctuation

Absolutely, check for a strong ground connection always....

[Jack H.]

Re: Amp guage fluctuation

Also with the lights on, you have to rev to approx 900-950 rpms for the generator to charge. Volt reg or gen??

Generator.

Generator's have a 'cut through' profile that dictates how much of their peak rated current output is available based on engine RPM. The older Parts & Accessory manuals typically show the curves...

Police cars and taxi cabs used 'special' generators with a more aggressive low end cut-through profile than ordinary passenger cars due to the amount of time they normally spent idling.

Bottom line, you get VERY LITTLE current output from the average generator until you're WELL above idle (figure 1200 RPM or so). So, it's NOT abnormal to see a battery discharge situation with these cars while they're at/near idle AND the electrical system drain is heavy (headlights on and/or heater blower motor running). That's just the way the 'beast' was in the good ole days!

[Al R.]

Re: Amp guage fluctuation

I charged the battery to approx full charge and cranked up the car. It only seemed to barely fluctuate. Hopefully, this weekend I can get it out on the road for an extended drive and see how it does. Also, I'm going to try to find time to go over all accessible connections and clean them. If that doesn't solve it, I'll probably try to install non halos. Thanks everyone for the good advice! Al