I was having some issues with my battery slowing going down. Watching the voltage of the system when driving it seemed like the voltage overall was low. Never having adjusted a voltage regulator before I looked here and in some other forums for tips and didn't find too much about the nitty gritty of actually doing the adjustment. Now that I've done it I suppose that's because there's not that much to it.
I thought I'd post here what I found and did in case someone else has a similar issue and comes looking for past experiences.
I have AC which should not be too much extra draw for the stock generator to handle. Yet the battery kept getting lower and lower on charge after a 15 mile trip. At idle, with the AC on, the voltage was dropping to as low as 11.9 after a couple trips. By that time, I could even tell the starter was cranking the engine over more slowly when starting. When at speed it would be around 12.6 . After putting the battery on a trickle charger and getting it fully charged on the next trip it would idle showing about 12.2 and at speed it would go up to about 12.8. That seemed too low and obviously was since it wasn't keeping the battery up.
I was starting to think I was going to need to put an alternator on it. But I figured I should at least attempt to adjust the voltage regulator. Reading up on it the book says to bend the lower tab that the spring for the voltage coil (the one with the really small wires inside the regulator) is hooked to. I thought I could test that theory by simply holding the contact points for that coil closed and the voltage would either go way up or way down. Yet holding them either open or closed seemed to have little effect on the voltage reading at the battery. I was thinking that perhaps my problem was that the whole voltage regulator was bad. Looked at the book again and it said the contact points would open and close between 60 to 200 times a second. Didn't seem to me they were even moving, perhaps it's such a small movement it's hard to tell. Since holding the contact points open or closed didn't seem to affect voltage the buzzing of the points and at different rates must be what's controlling the voltage.
In any case, I figured I may as well try bending the spring tab like the instructions say... bend it down to increase volage. So I did. Within several seconds the voltage was up... too far... at one point I had it up to 16 volts at around 2000 rpm! I adjusted the spring tab some more and settled on it going up to 13.9 at around 2000 rpm and at idle it sometimes drops to 12.4 .. those with the AC on. With the AC off it will run 0.1 to 0.2 higher.
Since making the adjustment I've made 3 trips with the AC on (about 50 miles total) and have checked the battery condition after each one. It has held at a SOH (state of health) of 100% and a SOC (state of charge) of 98%. It would seem the generator is able to handle the AC load as long as the VReg is adjusted to keep the voltage up where it needs to be.
Setting the voltage regulator
Moderator: Joe Johnston
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T-Bird Bob
- Posts: 143
- Joined: Fri Aug 10, 2018 11:00 pm
Re: Setting the voltage regulator
Hello Jimntempe.
Since you already know how to bend the springs in the regulator, I have no doubt you can adjust it right to 15V.
What you should take into consideration is that at idle, the generator does not charge. I think it needs some 1100 Engine RPM in general for the generator do output anything.
So this is typically what you see: When cruising above 1100 RPM, the voltage goes up to what the Generator can deliver. When you stop, the battery voltage slowly goes down to battery-only voltage (your 12.4). When you are drawing a current, you can even go below that.
So the trick is to stay moving for most of the time and avoid red lights etc.
In addition to that: Your Generator will only produce a max of 30Amps - If you run an AC with an electric fan, that is already drawing 10A.
With you head lights on, ignition, radio etc, another 10-12 Amps. So there isn't much Amps left to charge the battery. And those 30Amps probably need over 2000RPM to be produced.
If you are in Tempe (from your name) And you wanna go out on a 105° night, maybe you can head for the freeway and get out of town as fast as you an to keep the car moving (already for cooling the AC) and keep the motor above 2000RPM.
Good luck!
Bob
Since you already know how to bend the springs in the regulator, I have no doubt you can adjust it right to 15V.
What you should take into consideration is that at idle, the generator does not charge. I think it needs some 1100 Engine RPM in general for the generator do output anything.
So this is typically what you see: When cruising above 1100 RPM, the voltage goes up to what the Generator can deliver. When you stop, the battery voltage slowly goes down to battery-only voltage (your 12.4). When you are drawing a current, you can even go below that.
So the trick is to stay moving for most of the time and avoid red lights etc.
In addition to that: Your Generator will only produce a max of 30Amps - If you run an AC with an electric fan, that is already drawing 10A.
With you head lights on, ignition, radio etc, another 10-12 Amps. So there isn't much Amps left to charge the battery. And those 30Amps probably need over 2000RPM to be produced.
If you are in Tempe (from your name) And you wanna go out on a 105° night, maybe you can head for the freeway and get out of town as fast as you an to keep the car moving (already for cooling the AC) and keep the motor above 2000RPM.
Good luck!
Bob
Re: Setting the voltage regulator
Looking into this more... It's surprisingly difficult to find a graph of vintage gen output vs rpm. I was able to find one for a 1954 Buick 30-amp generator. At an engine speed of 800 rpm the generator can produce 12 amps. At an engine speed of 1000 rpm it can produce 24 amps. At 1200 rpm it's producing the full 30 amps. That's using a gen vs engine speed ratio of 2:1 which ought to be pretty much in the ballpark. There won't be any charging going on at a stop light, but recovery should be pretty fast once you get going.
Re: Setting the voltage regulator
That helps explain why many question why the gen light sometimes wants to start to glow at idle in gear. Mine only does that when warming up and just after the choke pulls off and is still a little lean until it warms up for another 20 seconds. Mine idles at about 6-700 RPM when warm and in gear.
VTCI # 13223
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T-Bird Bob
- Posts: 143
- Joined: Fri Aug 10, 2018 11:00 pm
Re: Setting the voltage regulator
The charge light is a different story.
The regulator as three coils that are using current through them to control things:
A) the voltage at which it shuts off the field current to the generator.
B) The current coming from the generator
C) the minimum voltage the generator needs to supply to stay connected to the cars electrical system.
A) controls your charge voltage, in this case the 15V for the 57 bird.
B) - I didn't figure out how to measure that without the original equipment and therefore left it alone.
C) is the "main switch": It separates the generator from the car's electrical circuit when the engine stops. Otherwise you would drain the battery through the field coils when parked (probably in less than an hour). This is also connected to the charge light. it just needs a small voltage to connect the generator. This is where the remanence magnetism inside the generator is important, because you need to generate some voltage even without the field coil being energized.
Sometimes this is not enough, especially when slow and cold and the generator light comes on because this switch doesn't connect the generator and battery.
But even if this voltage is high enough to have the generator connected, it does not generate enough voltage to charge the battery in idle.
Best of luck
Bob
The regulator as three coils that are using current through them to control things:
A) the voltage at which it shuts off the field current to the generator.
B) The current coming from the generator
C) the minimum voltage the generator needs to supply to stay connected to the cars electrical system.
A) controls your charge voltage, in this case the 15V for the 57 bird.
B) - I didn't figure out how to measure that without the original equipment and therefore left it alone.
C) is the "main switch": It separates the generator from the car's electrical circuit when the engine stops. Otherwise you would drain the battery through the field coils when parked (probably in less than an hour). This is also connected to the charge light. it just needs a small voltage to connect the generator. This is where the remanence magnetism inside the generator is important, because you need to generate some voltage even without the field coil being energized.
Sometimes this is not enough, especially when slow and cold and the generator light comes on because this switch doesn't connect the generator and battery.
But even if this voltage is high enough to have the generator connected, it does not generate enough voltage to charge the battery in idle.
Best of luck
Bob
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DynoDan’55
- Posts: 240
- Joined: Sat Feb 24, 2018 3:34 pm
Re: Setting the voltage regulator
Since regulator adjustment is rather a lost art, and they aren’t very expensive, you COULD just buy several and use the one that works best (nice to have spares anyway). An Optima battery & matched/sophisticated ‘smart’ charger likely makes an aftermarket ammeter superfluous if you always plug the charger in when parked. I can usually tell how worn the gen. brushes are getting by the glow intensity of the idiot light while driving at night with the brights, heater fan & radio on (especially when the OD solenoid’s hold-in coil activates). Charger alway connected when parked means never a starting issue (still 6V/+grd), plus it’s nice to know I’ll have enough juice to get back when the gen. fails far from home and the idiot light stays on. Of course, those who must have lots of added aftermarket electronic accessories should likely just get an alternator.
Re: Setting the voltage regulator
I agree that setting a regulator is an iterative process that takes some patience and skill. It is important to make sure that the voltage and current regulator coils are set to work together properly.
The other tricks are that a regulator is temperature sensitive (as noted in the shop manual) and the final checks need to be made with the cover installed. The cover alters the magnetic fields around the coils.
I am also surprised that it is difficult to find generator performance curves. I do know that output decreases with higher temperature due to the increased resistance to electron flow in the copper wire in the field and armature coils.
The other tricks are that a regulator is temperature sensitive (as noted in the shop manual) and the final checks need to be made with the cover installed. The cover alters the magnetic fields around the coils.
I am also surprised that it is difficult to find generator performance curves. I do know that output decreases with higher temperature due to the increased resistance to electron flow in the copper wire in the field and armature coils.
Rusty
VTCI 13079
VTCI 13079
Re: Setting the voltage regulator
I've been curious as to what my electric loads are, so I measured most of them today. And then went down a rabbit hole. Results...
ALL my bulbs have been changed to LEDs. However, I do have load resistors on the brake lights because without them the flasher would not flash. That is why the brake light amp draw is so high.
Everything off 0.015 (probably radio keep alive)
Door open interior lights on 0.33
Brake lights 2.6 (load resistors)
Parking lights front and rear 0.80
Headlights - taillights - low beam 3.56 (total both lights)
Headlights - taillights - high beam 4.55 (total both lights)
Key in acc position cycles between 0.07 - 0.40 (might be from the Constant Voltage Regulator cycling)
Key in ON position cycles between 1.3 - 1.7 (presumably the petronix ignitor and the electric choke)
Key in ON and AC on Highest speed 11.0 (net AC therefore 9.5)
Key in ON and Heater blower on low 4.0 (net heater therefore 2.5)
Key in ON and heater blower on high 6.0 (net heater therefore 4.5)
Radio played loud addition to baseline 1.0
Worst case steady load in daytime with AC on high, radio on 12 amps
peaks to 14.6 when brakes are on.
Worst case steady load at night with AC on high, radio on, high beams on 16.55
peaks to 19.15 when brakes are on
I forgot to measure my backup electric fuel pump but Holley says max amp draw for it is 2 amps
As reference, the old 7" sealed beams *each* draw 3.8 amps on low and 4.1 amps on high.
If at idle there is no useable gen output and idling is 20% of the drive time, then each hour the battery has to provide 20% of an hour's worth of electric power. Worst discharge case would be at night, stopped, with brake lights on, which totals roughly 20 amps. We only need to provide that for the 20% of the time so 0.20 hr x 20 amps = 4 amp-hours coming out of the battery during the stopped portion of each full hour of driving. But the other 80% of each hour the generator has an excess capacity of 13 amps. 30 amps - 17 (brake lamps aren't on) amps = 13 amps excess. 0.80 hour x 13 amps = 10.4 amp-hours excess generated power for charging the battery during the hour of driving. So in each hour we have the capacity to put back over twice what we took out of the battery as measured in amp-hours.
To show the flip side, if you were in terrible traffic and stopped for half of each hour...
When moving when gen can charge the battery ... 0.5 hr x 13 amps = 6.5 amp-hours available to recharge
Stopped and discharging.... 0.5 x 20 = 10.0 amp-hours being used up.
A deficit of 3.5 amp-hours that gets taken out of the battery and not replaced for each hour of driving.
These battery's have a total capacity of about 50 amp-hours but it's bad to drop them below half so let's say 25 amp-hours of safe usable capacity. 25 / 3.5 = 7.14 hours you could spend sitting in traffic watching your voltage drop and the temperature gauge climb. That's absolute worst case, you could turn the headlights off when stopped, let the brake off and put it in park and probably get it close to even or better.
Overall, the 30-amp generator (and all LED lamps) seems like it should be fine with my loads and the 20% stopped time situation. YMMV
ALL my bulbs have been changed to LEDs. However, I do have load resistors on the brake lights because without them the flasher would not flash. That is why the brake light amp draw is so high.
Everything off 0.015 (probably radio keep alive)
Door open interior lights on 0.33
Brake lights 2.6 (load resistors)
Parking lights front and rear 0.80
Headlights - taillights - low beam 3.56 (total both lights)
Headlights - taillights - high beam 4.55 (total both lights)
Key in acc position cycles between 0.07 - 0.40 (might be from the Constant Voltage Regulator cycling)
Key in ON position cycles between 1.3 - 1.7 (presumably the petronix ignitor and the electric choke)
Key in ON and AC on Highest speed 11.0 (net AC therefore 9.5)
Key in ON and Heater blower on low 4.0 (net heater therefore 2.5)
Key in ON and heater blower on high 6.0 (net heater therefore 4.5)
Radio played loud addition to baseline 1.0
Worst case steady load in daytime with AC on high, radio on 12 amps
peaks to 14.6 when brakes are on.
Worst case steady load at night with AC on high, radio on, high beams on 16.55
peaks to 19.15 when brakes are on
I forgot to measure my backup electric fuel pump but Holley says max amp draw for it is 2 amps
As reference, the old 7" sealed beams *each* draw 3.8 amps on low and 4.1 amps on high.
If at idle there is no useable gen output and idling is 20% of the drive time, then each hour the battery has to provide 20% of an hour's worth of electric power. Worst discharge case would be at night, stopped, with brake lights on, which totals roughly 20 amps. We only need to provide that for the 20% of the time so 0.20 hr x 20 amps = 4 amp-hours coming out of the battery during the stopped portion of each full hour of driving. But the other 80% of each hour the generator has an excess capacity of 13 amps. 30 amps - 17 (brake lamps aren't on) amps = 13 amps excess. 0.80 hour x 13 amps = 10.4 amp-hours excess generated power for charging the battery during the hour of driving. So in each hour we have the capacity to put back over twice what we took out of the battery as measured in amp-hours.
To show the flip side, if you were in terrible traffic and stopped for half of each hour...
When moving when gen can charge the battery ... 0.5 hr x 13 amps = 6.5 amp-hours available to recharge
Stopped and discharging.... 0.5 x 20 = 10.0 amp-hours being used up.
A deficit of 3.5 amp-hours that gets taken out of the battery and not replaced for each hour of driving.
These battery's have a total capacity of about 50 amp-hours but it's bad to drop them below half so let's say 25 amp-hours of safe usable capacity. 25 / 3.5 = 7.14 hours you could spend sitting in traffic watching your voltage drop and the temperature gauge climb. That's absolute worst case, you could turn the headlights off when stopped, let the brake off and put it in park and probably get it close to even or better.
Overall, the 30-amp generator (and all LED lamps) seems like it should be fine with my loads and the 20% stopped time situation. YMMV
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Alan H. Tast
- Posts: 4252
- Joined: Wed Aug 20, 2003 10:52 pm
- Location: Omaha, NE
Re: Setting the voltage regulator
(Doing my Arte Johnson Wehrmacht soldier-behind-the-fern voice) Verrry interesting. And that's why it's wise to use specialty consultants - if I as an architect didn't have electrical engineers to rely on, I'd be going down more than the rabbit hole...
Alan H. Tast, AIA
Technical Director/Past President,
Vintage Thunderbird Club Int'l.
Author, "Thunderbird 1955-1966" & "Thunderbird 50 Years"
1963 Hardtop & 1963 Sports Roadster
Technical Director/Past President,
Vintage Thunderbird Club Int'l.
Author, "Thunderbird 1955-1966" & "Thunderbird 50 Years"
1963 Hardtop & 1963 Sports Roadster
Re: Setting the voltage regulator
My '57 is as stock as I can keep it and have never had any issues other than my battery finally giving up after at least 8 years of use. It originally came with the group 32 HD battery but they are so expensive I had to do with the group 29 and put in a spacer block to make up for the smaller size.
VTCI # 13223
Re: Setting the voltage regulator
I want mine stock as possible too. Made a 30 mile trip yesterday and battery tested same as it has been, 100% health and 98% charged.ward 57 wrote: ↑Mon May 08, 2023 5:46 pm My '57 is as stock as I can keep it and have never had any issues other than my battery finally giving up after at least 8 years of use. It originally came with the group 32 HD battery but they are so expensive I had to do with the group 29 and put in a spacer block to make up for the smaller size.
Re: Setting the voltage regulator
Follow up to my earlier post in this thread where I was measuring my electrical loads with a regular in-series ammeter. I bought a amp-volt clamp around style meter that had Bluetooth, and which connects to your smartphone. It let me put the clamp around the negative battery cable and sit in the car turning things on and off and changing engine speed and seeing the real time amp draw in and out of the battery. Wish I'd bought it a long time ago. With this meter I was able to also measure the current draw for the starter.
Sorry for the format, it's the list of results in order of what I did. For those things which were the same as the last tests I did with the other meter the results are pretty close to the same, certainly good enough for my interests and needs.
These tests were made using the clamp meter on the negative battery terminal.
Key on engine off 1.7 to 2.0 but settles at around 1.8, probably as the choke and cvr warm up.
Add radio gives total of 1.8 - 2.0. depending on loudness.
Turned radio off, has KO base of about 1.2 now, choke warmed up more presumably.
then add AC (clutch comes on) LOW 8.3 (net about 8.1)
MEDIUM 9.7 (Net about 8.5)
HIGH 11.6 (net about 10.4)
Back to base, KO engine off 1.1
Brakes add 4.8 (net 3.7)
Headlights HI 6.4 (net 5.3)
Headlights Low 4.8 (net 3.7)
Parking lights 1.7 (net 0.6)
Back to base 1.0
Heater Blower LO 3.9 (net 2.9)
Heater Blower HI 5.9 (net 4.9)
Back to base (engine off, nothing on but key is "on") 1.0 amps
I did not set the choke or pump the gas to make sure engine would not start yet. Ran the starter several times to pull down the battery at bit so it would need to be charged when I did start the engine.
Set the choke and gave it a couple pumps and started engine.
Starter draws 200 amps as a ballpark figure. Sometimes it was as low as 180, sometimes it went up to 215, so I'm calling it 200.
Start Engine and run at 1200 rpm. - about 20 amps was going into the battery with nothing on.
at 800 rpm about 8 amps going into the battery, nothing on.
Then turned the AC on HI and 9 amps was coming out of the battery, still at 800 rpm
Put car in drive, rpm dropped to 600... 16 amps now going OUT of battery with AC on high.
Turned AC Off and still in gear, 600 rpm, 5.5 amps going OUT of battery
sped engine up to 900 rpm with AC on HI, still in gear, and now get 5 amps INTO battery.
Next... Engine running, AC on, Headlights on HI, Heater blower on HI......
at 800 rpm 14 amps OUT of battery
at 1200 RPM 0.0 amps into or out of battery.
at 2500 rpm 8 amps INTO battery.
===================
Sorry for the format, it's the list of results in order of what I did. For those things which were the same as the last tests I did with the other meter the results are pretty close to the same, certainly good enough for my interests and needs.
These tests were made using the clamp meter on the negative battery terminal.
Key on engine off 1.7 to 2.0 but settles at around 1.8, probably as the choke and cvr warm up.
Add radio gives total of 1.8 - 2.0. depending on loudness.
Turned radio off, has KO base of about 1.2 now, choke warmed up more presumably.
then add AC (clutch comes on) LOW 8.3 (net about 8.1)
MEDIUM 9.7 (Net about 8.5)
HIGH 11.6 (net about 10.4)
Back to base, KO engine off 1.1
Brakes add 4.8 (net 3.7)
Headlights HI 6.4 (net 5.3)
Headlights Low 4.8 (net 3.7)
Parking lights 1.7 (net 0.6)
Back to base 1.0
Heater Blower LO 3.9 (net 2.9)
Heater Blower HI 5.9 (net 4.9)
Back to base (engine off, nothing on but key is "on") 1.0 amps
I did not set the choke or pump the gas to make sure engine would not start yet. Ran the starter several times to pull down the battery at bit so it would need to be charged when I did start the engine.
Set the choke and gave it a couple pumps and started engine.
Starter draws 200 amps as a ballpark figure. Sometimes it was as low as 180, sometimes it went up to 215, so I'm calling it 200.
Start Engine and run at 1200 rpm. - about 20 amps was going into the battery with nothing on.
at 800 rpm about 8 amps going into the battery, nothing on.
Then turned the AC on HI and 9 amps was coming out of the battery, still at 800 rpm
Put car in drive, rpm dropped to 600... 16 amps now going OUT of battery with AC on high.
Turned AC Off and still in gear, 600 rpm, 5.5 amps going OUT of battery
sped engine up to 900 rpm with AC on HI, still in gear, and now get 5 amps INTO battery.
Next... Engine running, AC on, Headlights on HI, Heater blower on HI......
at 800 rpm 14 amps OUT of battery
at 1200 RPM 0.0 amps into or out of battery.
at 2500 rpm 8 amps INTO battery.
===================
Re: Setting the voltage regulator
I read above that the generator has no output at idle. Is this true? When I rev it up it puts out 13+ volts. Is this normal? I would think at idle it should put out something. At any rate, I'm rebuilding my generator this spring but should I look at the regulator also? The light stays off when running.
VTCI # 13223
Re: Setting the voltage regulator
Generally, generators charge little at idle. It takes around 1000 rpm to go to full charge rate of 13.7 to 14.3
ward 57 wrote: ↑Thu Mar 07, 2024 8:24 pm I read above that the generator has no output at idle. Is this true? When I rev it up it puts out 13+ volts. Is this normal? I would think at idle it should put out something. At any rate, I'm rebuilding my generator this spring but should I look at the regulator also? The light stays off when running.
1956 Fiesta Red 312
1954 Ford Victoria 312
1948 Ford Convertible Street Rod 302
1954 Ford Victoria 312
1948 Ford Convertible Street Rod 302