12V voltage regulator output. What is normal? Edit: I goofed!
 

Edit: Sorry for the hullabaloo but I just discovered the problem. It was my fault. See my post lower in the thread.

Hello. I just fitted a new Voltage regulator to my truck, and I am a little concerned at the numbers I am seeing.

It is a brand new, made in the USA unit. The typical type with the blue lid.

With the truck at about 40 mph the ammeter is pegged positive and the max voltage reading I saw was 17.6 volts.

I'd say that is much too high and would be at a level where I would start blowing lights or other components.

I fitted this unit because the old one (also relatively new) is under charging.

So I wondered what other peoples experiences are with these units.

Is it reasonable to expect me to try tweaking a brand new unit?

Is there an alternative unit that is more reliable, that is compatible with a Ford type generator?

I looked at a VW beetle unit but came to conclusion the field wires are wired the other way so it would not work with The Ford generator.

I was hoping to see just over 14V and a steadily reducing ammeter reading. Is that unreasonable?

Thanks. Mart.

Here's the unit. A Standard VR21.

https://www.fordbarn.com/forum/attac...3&d=1640107865

Re: 12V voltage regulator output. What is normal?
 

much too high dont run it or you burn up generator and more should be 14.2 14.4

Re: 12V voltage regulator output. What is normal?
 

Is the unit grounded, ah, earthed properly? A "lifted" ground could possibly cause trouble as the regulator loses reference. A heavy jumper wire from regulator base to battery ground terminal would be an easy test for this.

Be careful of what you are measuring with. I know you know this, but digital VOM with a weak internal battery will indicate incorrect voltages, well to the high side. The first time this happened to me caused some head scratching.

Generator charging systems do have a markedly higher set point than alternator charging systems. Both are subject to a correction factor based on temperature, a generator charging system should average nearly 1 volt higher than an alternator at subzero temperatures. When numbers like "14.2 volts" are mentioned this is adequate or spec at 77° F. Regulators are compensated for ambient or battery temperature.

High 15s are in specification depending on temperature and battery state of charge. 17+ however is way, way off the beam. You can try to make adjustments but it is a bit tricky. If you can get a replacement that would be better.

Re: 12V voltage regulator output. What is normal?
 

First may I state that just because a regulator is new does not mean it is set correctly. A normal voltage setting should be 14.2 volts but this can vary slightly depending on battery state of charge and condition and any loads that are switched on. Also as stated already there should be a ground wire between the regulator base and the generator case. Also good connections in the main battery cable from the regulator to the starter solenoid main battery cable side connection or ammeter connections. Any bad connection in this charging line can cause the voltage to go high. I ask why did you replace the regulator in the first place ? Electro mechanical regulators can be adjusted but only if you know what you are doing here. The various adjustments to be considered on a voltage regulator are cut out opening and closing voltage and reverse current. Current regulator setting to match the safe amps output of the generator and the voltage regulator settings. As mentioned in above post that a high 15 volt setting could be ok but I dont know where this info came from because that setting is way too high. I would regard a setting of 14.5 volts as being a maximum. Always use a good analog automotive meter test set comprising of a voltmeter and ammeter for setting these regs up. Digital voltmeters dont cut it. Regards, Kevin..

Re: 12V voltage regulator output. What is normal?
 

I have been dancing with regulators, about 6 of them, 6v, and two different makes, for the last 5 years. Once upon a time the rule was to NOT try and adjust them. This dance involved switching parts (batteries, generators and regulators) on two different 8BA vehicles. Some I returned as they would not work right out of the box, one worked well until it got warm and then nothing, others would work for a short time. Generators and some regulators were checked and adjusted at a very competent shop. I have only tried 2 different makes but the one in the pic is one of them, the other sourced thru carpentar. I got down to 2 that "sorta" worked on one vehicle but not the other. I have 3 on the shelf that might work but at present do not. As these are generally not returnable it becomes a real money pit. Out of sheer desperation I did (successfully) adjust two to work properly, hopefully for a long time. It seems to make a difference depending which generator and or battery combination as to what is required. I think this defies logic but it works. Be aware that the adjustments have to be absolutely miniscule if you are going to try it. For those that are going to respond about grounding or wiring issues being the problem, please do not, as I have long since chased down that road. I agree a analog meter should be used as these old electrical systems do not like digital at all. Worked for me.

Re: 12V voltage regulator output. What is normal?
 

Knowing EXACTLY what you are doing here is most important not just guessing. TESTING, TESTING, TESTING is how its done and not just swapping parts around in the off chance you will fix it. If I just guessed and swapped parts around I would be out of business in no time. Regards, Kevin.

Re: 12V voltage regulator output. What is normal?
 

Thanks Kevin; appreciate your thoughts. I guess the point I was trying to make is that you MAY have to adjust these regulators rather than use the old approach of "do not touch". The adjustment procedures are in the service manuals for these old cars, they just need to be used. In one case I had the reverse of Morts situation, with a low battery it would charge at about 6.3 (if I remember correctly) when it should have been up in the 7 or better range, barely kept the battery alive, adjusted to a little over 7 and battery is happy.

Re: 12V voltage regulator output. What is normal?
 

?? It comes straight out of the Ford shop manuals. Battery charging voltage is actually a bit of a moving target. This is one reason DIYers with their magic screwdrivers can get into trouble quickly trying to adjust voltage output. The specific regulator set point is always temperature dependent, along with some other variables.

Regulator calibration or adjustment specs ensures that the correct charge voltage will be applied throughout very wide temperature swings. Basically the internal regulator temperature compensation allows for higher average charge voltage in colder weather, and lower charge voltages at high temperatures. This is because of the increased internal battery resistance as the ambient temperature goes down. You are correct in saying that 14.x volts is on the high side but this figure only really applies at the "standard" temperature of 77° F.

(For example, at 0° F., a correction factor of about +1 volt is applied to the set point charging tables compared with the "standard" temperature of 77°. Again no adjustment is required for this to happen, it is an automatic part of the regulator mechanism).

Re: 12V voltage regulator output. What is normal?
 

generator regs are mechanical and require setting when fitted if this is beyond you get some expert help your local auto elec!! What was wrong with the old one it may have only required a reset or you may have other problems [bad wires/connections ] nothing burns voltage like a bad connection, definitely wouldn't run it at 17volts should be around 14,24 so anywhere between 13,24 to 14.5 is acceptable

Re: 12V voltage regulator output. What is normal?
 

PS mechanical regs should only be set with a fully charged battery as battery voltage effects the charge rate

Re: 12V voltage regulator output. What is normal? Edit: I goofed!
 

Thanks for all the interesting and educated discussion.
I found the problem and it was a mistake on my part. I put my hand up and apologise for setting a ball rolling that was not necessary.
I tried backing off the adjustments but could not detect a change. i studied my connections and found I had my field wire connected to the arm terminal. I had mistook it for the wire that goes to the ignition charging light. (which I never finished installing by the way).

Connected correctly the regulator was not charging at all, which was not surprising by the amount I had backed it off while trying to adjust it when connected incorrectly.

I tweaked the adjustments up and can now see what I would say are good numbers up in the low to mid 14s and the amps settling out nicely.

I am annoyed at myself because when I tried to flash my "field" wire (actually an incomplete ignition warning light wire) I did not get a spark. I couldn't understand it but carried on without realising that should have been telling me something.

Ok. All good now so thanks all for the information.

Mart.

Re: 12V voltage regulator output. What is normal? Edit: I goofed!
 

Thanks for your confession, Mart. If the terminals weren't so clearly marked, I'd probably have connected the field wire to BAT, the armature wire to FLD, and battery wire to the ARM. Cuz that's how I remember them from the old days before the wonderful alternators were available cheap. However, the terminals do seem to be pretty clearly marked. But you're foregiven anyway. :D


https://www.fordbarn.com/forum/attac...1&d=1640215217