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Amp Gauge too High

5K views 43 replies 13 participants last post by  kwschumm 
#1 ·
I have had a problem with the charging system on my GT after taking out of storage and driving it to a car show. It worked fine all day but the next morning the battery was dead. I found no shorts or anything on. I had the charging system tested at Oreilly's and they said the battery was good (whew! Red Top) - bad Voltage regulator. I tried another one... same thing. I ordered a new VR from them and a couple days later put it on and went back to them, they said VR was still showing bad. I didn't believe them and instead ordered a reman alternator from RockAuto. I put it on today and the amp gauge is showing 30amps at idle. I believe everything to be hooked up correctly after installation. I tried a diff VR and it shows the same thing. Would it be high if the battery were fairly drained?? I don't think the alternator should be putting out 30 amps at idle assuming it is reading correctly. Normally, it sits slightly to the right of 0 until you turn something on. Any thoughts? The rebuilt alternator is bad?
 
#2 ·
If the battery has not been re-charged after it ran down, then the ammeter WILL shows a high charge current until the car is driven for 20-30 minutes and the battery gets charged.

Go and buy a volt-ohm meter right now before you do anything else. Not one to put in the car, but one to test with. Start the car and measure the voltage across the battery terminals with the engine idling at 1500-2000 RPM. The measured voltage on the battery terminal should be in the range of 13.6 to 14.4, maybe a bit + or - but in that range.
 
#4 ·
I've had a LOT of trouble with my GT's eating batteries over the years. I've gone through dozens of batteries. I'm so paranoid that the only time my car isn't on a charger is when I'm driving it. As soon as I park it in the garage I attach the trickle charger. Do not charge your battery on the "fast" setting, if your charger has one. Not good long term. Use the lowest setting. I put external charging posts on my car to make the charger hook up easier. You might have poorly connecting or corroded wires or terminals. When testing battery voltage at various times, make sure to put the voltmeter probe on the terminal itself, not the wire clamp, you want to make sure you're testing what the battery is getting, not what's in the wire.
 
#5 ·
I've had a LOT of trouble with my GT's eating batteries over the years. I've gone through dozens of batteries.
Well, clearly there's a parasitic load somewhere that you don't know about.

I'd throw an ammeter across your terminals and see just how many milliamps it's sucking.

And, instead of the annoyance of plugging in non-stop, why not instead just get a little dash-mounted solar charger? Usually it's plenty enough to tackle small drains somewhere. They're cheap.
 
#13 ·
All 5 of my GT's over 40 years had issues with batteries draining down. It's a common problem that many of us suffer. There's a number of threads on this site about the lengths that some people have gone to to stop it. The best seems to be to install a battery disconnect, like from a boat, somewhere. I had one under and behind the seat in the car that I put 225K miles on and drove daily to work. Before that, if I didn't drive it for 3 days I'd have a weak battery. The concensus is that it's hysteresis loss at all the various connectors and unused terminals. Of course, disconnecting your battery causes you to lose any presets or programming in your radio.

My present car has an aftermarket fuse box and wiring and all the gauges and stuff are newer, more modern, ones, so the problem coming from the wiring/fuse box/and device connections is diminished. But I have a bunch of electrical devices. I have to have door poppers because the PO removed the door handles. That has to stay partially on in order to receive the signal from the remote. I have decorative plasma plates in the back that may or may not be drawing some current to charge up capacitors, even though they're off 99% of the time. My car is always stored in a garage, so a solar charger on the dash wouldn't help me. I only drive the car on weekends and I have those external battery posts just in front of my left front wheel well, so it's really not a big deal for me to clamp the charger onto them. However, I'm a dumbass and I keep forgetting to disconnect the charger before going for a drive. Luckily there's a "dumbass disconnect" on the charger that unplugs when I roar off into the sunset. I made my own "dumbass defeat device" : I have a big yellow sign that I always carry in the car that I prop up on the dash to block the windshield. It says: "UNPLUG THE CHARGER DUMBASS!"

🤪
 
#6 ·
Check the wiring harness between the regulator and the alternator. I had a similar issue because one of the connections was loose due to a partially melted connector housing. As a result, the alternator went "full on" and burned itself and the regulator up. OGTS sells replacement cables.

Good luck!
 
#7 ·
Yes, you have a serious regulation problem OP. It's not at all likely to be in the alternator... it is putting out what is commanded to it by the regulator. The regulator senses what the system voltage is, and then uses that to tell the alternator how hard to charge. The problem could be in the regulator, or it could be in the wiring TO the regulator that the regulator uses to sense the system voltage.

Turn the ignition switch to RUN but do not start the car. Is the generator idiot light glowing? If not, then the problem is probably in the light blue wire with the white tracer that connects from the main harness into the regulator-to-alternator harness. There is a fusible link where it connects to the regulator-to-alternator harness; that is a soft, floppy section of wire. If that is burned out, then the regulator cannot sense the system voltage. The link needs to be replaced by another link or a fuse.

Here is a source of the info and wiring diagram that you might find useful; the charging system diagram is near the end. https://www.opelgtsource.com/system.../17OpelGTElectricalSystemNotes.pdf?1540360105
 
#16 · (Edited)
When you say the voltage went down with the old alternator what voltage did it go down to? Remember, make these voltage measurements only at a fast idle, like 1500-200 RPM and make them across the battery terminals.

Is the generator light working normally?

We need plenty of feedback on the details of what you find and measure if we are going to be able to help. It is hard to see your voltmeter through the internet....!
Sorry. Voltage at idle (about 1500 rpms) went to 13.something and amp gauge started acting normal - just above zero and fluctuating when something is turned on in compensation. I have a battery disconnect on the battery and have been disconnecting it at night. At present, I do not see an amp draw. I am going to leave it hooked up tonight to see if it goes down. I have checked the voltage regulator harness and verified continuity across the fusible link to the fuse box. No issues anywhere. I had also tried multiple voltage regulators with that rebuilt alternator - one was brand new and they all did the same thing. High voltage. Now old Alt is normal.

Gordon, I have all my plasma displays disconnected, have turned off the flux capacitor ( I know you have one of those too!) and ejected the warp core! 😀.
 
#8 ·
See the above link. Don’t spend any more money on it. The alternator harness is just mis wired somewhere. Check everything on that little plug in back of the alternator and voltage regulator. Use the ohm function on your multimeter and make sure that you have continuity on both sides of each wire and that the idiot light in the amp meter glows.

It’s usually the voltage regulator that causes this problem, but the wiring to the regulator can also cause this.
 
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#10 ·
Thanks for all the advice. Ill check out the harness and the link. The harness was a new one from Gil. Hoping it is not melted. Likely the fusible link. Ill check and let you guys know. I put an old alternator back on and the amps and voltage went back down. It could be that the rebuilt one is mis-wired.
 
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#15 ·
When you say the voltage went down with the old alternator what voltage did it go down to? Remember, make these voltage measurements only at a fast idle, like 1500-200 RPM and make them across the battery terminals.

Is the generator light working normally?

We need plenty of feedback on the details of what you find and measure if we are going to be able to help. It is hard to see your voltmeter through the internet....!
 
#11 ·
Probably not helpful at all, but funny story. Sometime back I had a problem with the battery going down on the GT when it sat for awhile. Could not figure it out for the longest time. Happened to go into the garage one evening after dark and noticed the dome light on. Shut it off, no more problem.
 
#12 ·
I have really small light motorcycle batteries in both of my GTs. My clock will drain those suckers to 11.5V in a couple weeks. I can hear those dang clock solenoids through my garage wall when it’s really quiet in my house.
Tick tick tick tick THUUUUNK tick tick tick tick. Lol
 
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#17 ·
OK, if in the high 13's then that is OK.

Low 13's is not.... If that, it might be a poor regulator, but you have changed that. So might be a diode blown in the old alternator.

BTW, never disconnect the battery with the alternator system running.... some of those old electro-mechanical regulators would readily burn up if you did that.

And a good charged battery will show 12.6-12.7 volts disconnected and after 'resting' (not being charged or discharged) for at least 30 minutes. So you might go out in the AM and check that, after disconnecting the battery for 30 minutes. If low, then the battery may need to be charged, or you have a discharge somewhere.

If you have noticed, your voltmeter is a your best troubleshooting tool for these systems.
 
#20 ·
So might be a diode blown in the old alternator.
I wondered. Seems like the Alternator makes all the difference in my situation. I keep coming back to it and think that I just got a crummy rebuild from Rock Auto. The old alternator drained the battery with a short, the new one had some other crazy problem. At least thats what I am thinking.


BTW, never disconnect the battery with the alternator system running.... some of those old electro-mechanical regulators would readily burn up if you did that.
Good to know. Thanks!
So this morning, I got right up and came out to check the car before I read your post. It cranked good and started right up. I had installed a new Weber from Gil yesterday evening and was anxious to give it a spin. I should have checked the battery voltage first! Duh. Anyway I drove it around and the Carb is fantastic.
So after the drive the battery sitting with the motor off is 12.59V. Started and revving to 2500rpms it only just slightly over 13V. Not sure if I should worry or not. At idle its just at around the 12.59 mark.

If you have noticed, your voltmeter is a your best troubleshooting tool for these systems.
Yes, thanks. I figured. I have not had a lot of issue with the charging system with my past GTs and do not know what the measurements are supposed to be under what circumstances or how the alternator/VR interacts.
I have another rebuilt Alt from Oreillys coming tomorrow to replace the parts car atrocity that I have in there now. Hoping it acts normally.
427126
427127
427128
427129
 
#18 ·
Thanks, the SciFi Guy, I've joined your club. "However, I'm a dumbass and I keep forgetting to disconnect the charger before going for a drive ". On one of my other cars, the battery tender was connected to the battery in the trunk. I drove off without disconnecting the tender. I thought people were waving at me as i drove down the road and I smiled and waved back. It was only at a traffic light when the car beside me said that there was something dangling behind my car. I now put a sign on the windshield to remind me to disconnect the tender.

Be safe.
 
#21 ·
Nice car!
 
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#24 ·
Ford electro-mechancials would blow regularly. Please don't argue about it; seen it too often.

The battery is a ballast to the system. Disconnect it and the voltage is going to shoot up at least momentarily. It is a control system with a response time and that time constant is what allows the spike. Put an oscilloscope on it next time.... With no battery ballast, the voltage spikes can go to over 100 volts. Put 12 volts on the field winding and see what you get at the alternator output.. but disconnnect the car first!

So you may have gotten away with it or other stuff may have loaded it enough to keep the spike down to where it did not blow anything; but no guarantees that the over-voltage won't eventually get something. Especially newer electronic stuff.

Disconnecting the battery when the alternator is running is a bad practice, and it is not good to say to others that it is OK. Just because you have not seen it does not mean it does not happen. This is kinda like telling guys to not leave the ignition ON when the engine is not running on a flathead V8. They will not believe that it will burn up the coil until they do it at least once.
 
#25 ·
Ford electro-mechancials would blow regularly. Please don't argue about it; seen it too often.
... "Hmm, why's that? It should ..."

Just asking a question.

There's tons of anecdotal evidence that's just outright wrong, or stories passed from one person to another. No harm in asking for or listening to an explanation.

This is relevant to Fords. Is it relevant to Opels?

You have lights and other electrical load for some measure of ballast. How big of a load is required to not have it trip out?
 
#26 ·
In the first comment I saw:
...tested at Oreilly's and they said the battery was good (whew! Red Top) - bad Voltage regulator

For a while I had problems where the voltage regulator seemed to fail very quickly. I don't have really hard evidence, but I have the suspicion that the problem resulted from hooking up a trickle charger that has a high-frequency desulfation cycle, when used with a solid state Regulator. It seems really unlikely to me that manufacturers of chargers would produce something that would damage a solid state regulator, at least now that we're well into the 21st century, but I stopped having the problem if I connected the charger to the battery when it is removed from the vehicle.
 
#27 ·
In the first comment I saw:
...tested at Oreilly's and they said the battery was good (whew! Red Top) - bad Voltage regulator

For a while I had problems where the voltage regulator seemed to fail very quickly. I don't have really hard evidence, but I have the suspicion that the problem resulted from hooking up a trickle charger that has a high-frequency desulfation cycle, when used with a solid state Regulator. It seems really unlikely to me that manufacturers of chargers would produce something that would damage a solid state regulator, at least now that we're well into the 21st century, but I stopped having the problem if I connected the charger to the battery when it is removed from the vehicle.
Useful information. What brand charger do you have?
 
#30 ·
I’ve heard that you shouldnt use trickle chargers on certain type batteries. Maybe gel batteries.

At any rate, I got my second new alternator from Oreilly’s today and installed it. All is well. No battery drains, the second new alternator has no high amps and no excess voltage. Going to take the car back to O’reilly’s and have them check it again to see if it still show voltage regulator issues. If not, I think the problem is licked. If they do show problems with the VR, then Im going to get another opinion from Autozone!
 
#31 · (Edited)
Seriously.. if you use your voltmeter, and check the fast idle voltage at the battery terminal, and it is in the 13.6 to 14.4 range then you are 100%.

You can truly trust that more than the tester at the box auto parts stores. Some of them are not well set up for some older systems, and the knowledge of the operator can make or break the usefulness of their testing. These are not knowledge people.
 
#32 ·
Serioulsy.. if you use your voltmeter, and check the fast idle voltage at the battery terminal, and it is in the 13.6 to 14.4 range then you are 100%. You can truly trust that more than the tester at the box auto parts stores. Some of them are not well set up for some older systems, and the knowledge of the operator can make or break the usefulness of their testing. These are not knowledge people.
Agreed. A good old multimeter works fine. Do a test with and without load on the electronics and see if the voltage stays above 13V if it does you are good like Manta Rallier says.
 
#37 ·
Knowing if your VM is reading accurately is why I inlcuded the last paragraph in my last (long boring LOL) post:

"Voltmeters are cheap and plentiful nowadays, and easy to field calibrate: check the voltage on a brand new 9V batttery; it ought to be 9.6-9.7 volts. If your voltmeter reads that, then your voltmeter is reasonably well calibrated for good field measurements."
 
#38 ·
Sold my last Opel a few years ago, along with manuals, wiring diagrams and notes. I'll have to do this from memory.

How many people have checked to determine that the analog ammeter is working properly as this is part of the charging circuit ?? An ammeter works by measuring voltage across a very low ohm, high current resistor. Ballpark might be 0.05 ohms capable of carrying 100 amp of current. What we think of as the ammeter is actually a voltmeter measuring the V= IR voltage drop across a high current shunt resistor. Usually the battery and starter are on one side of the ammeter, the alternator and the rest of the car the other. Depending on current flow to/from the battery the polarity of the IR voltage drop is positive or negative.

The reason this is important is if the shunt resistor is defective, has bad contacts or open, the ammeter will not function properly, and charging may not occur. For example if the shunt resistor is open or disconnected very little current will flow to the battery. At the same time the ammeter will read high, usually pinned in one direction or another. As connections degrade, functions such as lighting become unreliable and over the years people wire around the ammeter circuit.

This is a bane of many old cars with analog guages, in particular, old school ammeters.

Modern systems usually put the shunt in a protected place near the battery and use a sensor to send a digital signal back to an alternator.

Another approach might be to get rid of the ammeter entirely. Replace the alternator with a modern, one wire (plus ground through the engine) high capacity GM alternator (with integrated voltage regulator), wliminate the ammer etr circuit and eventually try to find a reasonably match voltmeter to put in it's place.

Hope this helps.
 
#39 ·
One way alternators were designed for tractors, they function as if they are pissing electrons into the wind. There is no feedback in the loop to prevent over/under charging. A lot of guys use them because they are easy but not because they are the best regulated solution. Manufacturers would use them from the factories if thought they were good enough to save a few bucks.
 
#42 ·
It's not that the 1-wire doesn't have a regulator, it does, but it doesn't kick in until the alternator spins up high enough to turn it on. It also only sees the demand from the "most optimistic" standpoint, i.e. if the alternator measures voltage it is putting out and pretty much ignores the rest of the electrical system, like the battery.

Here's a pretty good article that describes the differences.

 
#43 ·
Ah, OK, tnx. I did not think that old tractors would have the equivalent of a newer 1-wire. How old are we talking?

Just ramblin'..... 1-wires have been know to occasionally lose their residual magnetism in the core of the field winding after sitting unused for a while, which is needed to self-excite and start up. Not a rampant problems at all, seems like it just effects a few. So I still prefer the standard GM internal regulator types, with the separate power output and the 2 lead regulator connection.
 
#44 ·
Ah, OK, tnx. I did not think that old tractors would have the equivalent of a newer 1-wire. How old are we talking?
They go back a long way, I think mostly people used one-wire alternators to replace original generators or when converting 6 volt systems to 12 volts.
 
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