Alternator regulation

[ndutton]

Moved from another thread

Originally Posted by High Hopes

You can think of a depleted battery as a pool of water that needs filling. Water is the current. A guy Laboring at the pump is the voltage. The Drag at the pump is the resistance. A Battery has more Drag when it is depleted compared to when it is full. So in order to overcome the Drag, more Labor (volts) is needed to get a decent Water Flow (current). As the pool fills, the Pump becomes easier to work, so less Labor (voltage) is needed to keep the water flowing.

So yes, the voltage is adjusted to regulate the charging. This mechanism isn't delivering voltage (Labor), but delivering current (Water). In electrical engineering terms, this is called sourcing current, not voltage regulation. Go figure.

Originally Posted by ndutton

Well, you know I'm not in agreement at all but for the sake of discussion, what voltage range are you talking about?

In support of my previous posts that the regulator strives to maintain a constant voltage by varying the amperage to meet the combination of connected loads and the battery's needs, here is an excerpt from Hiller's Fundamentals of Automotive Electronics, 2nd Edition, P. 153:
Regulator
Output voltage from an alternator must be limited to prevent the battery from being overcharged and to protect the electrical equipment from excessive voltage. On a 12V [specific brand alternator] the regulator sets the alternator voltage to 14.2V.
Since this voltage corresponds to a fully-charged battery, the alternator must be made to vary its charging current to suit the state-of-charge of the battery. [end citation]

We're not talking about fancy programmable 3 stage systems that address only the battery with bulk, float and equalize stages but rather our typical A-4 alternator producing electricity under way with sensitive electronics operating like GPS, plotter, knotmeter, depth sounder, VHF, possibly radar, autopilot, etc.

Originally Posted by High Hopes

Hi Neil,

I think we are closer in understanding than you might think.

Quote, "Output voltage from an alternator must be limited to prevent the battery from being overcharged." Yes, the battery should not be constantly charged ad-infinitum.

Quote, "and to protect the electrical equipment from excessive voltage.," right again, 20 or 100 volts will fry stuff, so we have to limit the thing at some point.

On, "…a 12V [specific brand alternator] the regulator sets the alternator voltage to 14.2 V. Since this voltage corresponds to a fully-charged battery…". 14.2 volts is not a fully charged battery; 12.6 volts is a full charge. 13.2, 13.4, 13.8, are float charge voltages so this passage is not clear to me.

Interestingly enough, the part count inside a regulator is relative low. These devices are simper than one might think, but very cleverly designed. I think most engineering types would characterize the basic circuit as a current source with two constrained ways of operating. This is partly a semantic argument, too. The schematic I am thinking about could be drawn another way to make it look like a voltage regulator with current source operation provided between trip points.

The 14.2V figure was in the quoted text, I repeated it verbatim. Here's a chart we've posted before.

I don't think we're actually that close. One of us says charging is controlled by varying the alternator output voltage, the other says the output voltage remains constant and it's the amperage that's varied. I'm still struggling with the variable voltage comment and the effect it would have on voltage sensitive electronics.

[joe_db]

Some basics:
Alternators are controlled by the amount of current going through the field.
Basic regulators are set to one voltage. We'll use 13.8 for an example. The regulator will add more current any time the voltage is under 13.8 and reduce current whenever the voltage is over 13.8. That is all it does - try and hold the voltage to 13.8. The alternator itself will have a maximum output. At some point the voltage will be falling below 13.8 even with maximum field current.

Notice batteries are not in the picture yet. The simple regulator does not care what the load is. All it does is vary field current to try and hold the pre-set output voltage.

I'll post on more sophisticated regulators in a bit.

[High Hopes]

Originally Posted by ndutton

Moved from another thread.
I don't think we're actually that close. One of us says charging is controlled by varying the alternator output voltage, the other says the output voltage remains constant and it's the amperage that's varied. I'm still struggling with the variable voltage comment and the effect it would have on voltage sensitive electronics.

But he voltage is not constant, the voltage changes. That is what my voltmeter shows. How can that be with a voltage regulator?

Also, the electronics are not sensitive to voltage. When the engine is off and the house circuits are drawing power, the battery still works down to about 10.2 volts. Who hasn't drawn batteries down this far? Everything still works. The lamps are dimmer, but the radio, GPS, sounders all still work. Power on radio transmit may be limited, maybe, but it only needs a few amps. The GPS warns me that the voltage is low, but it still works. And when the engine is running, you have stated that the voltage goes to 14.2. Everything works then, yes? So at a minimum, the operational range of "twelve volt" gear on the boat is 10.2 to 14.2 volts.

I'll take a deeper look at your references later today when I get a chance.
Cheers,
- Steve

[High Hopes]

Originally Posted by joe_db

Some basics:
Alternators are controlled by the amount of current going through the field.
Basic regulators are set to one voltage. We'll use 13.8 for an example. The regulator will add more current any time the voltage is under 13.8 and reduce current whenever the voltage is over 13.8. That is all it does - try and hold the voltage to 13.8. . . . .

Hi Joe,
This may be basically true for regulators in general, but not true for the regulator in my alternator. Maybe we talking about two types of alternator regulators? Is your alternator older? Have you measured the voltage over time? My readings do not show one constant voltage. - Steve

[ndutton]

Originally Posted by High Hopes

But the voltage is not constant, the voltage changes. That is what my voltmeter shows. How can that be with a voltage regulator?

I'll take a deeper look at your references later today when I get a chance.

While you're checking my references, here's another one:
http://en.wikipedia.org/wiki/Alternator

Automotive alternators require a voltage regulator which operates by modulating the small field current to produce a constant voltage at the battery terminals.

Are you sure your regulator is working properly? Your report of different voltages suggests to me it's not regulating the voltage very well. In the other thread I asked about the voltage range you were experiencing and I don't recall the response.

[joe_db]

On to part II:
So what happens when you add a battery to the system?
Think of a battery as a variable load. The lower it is, the more current will flow into it at a given voltage. Let us take a large battery - say a 220 AH 8D - and a typical A4 alternator of 35 or 50 amps. Let us say the battery is near dead. A near dead 8D will accept a LOT more than 35 or 50 amps, so what happens first is the regulator applies full current to the field. The alternator is putting out as much current as it can, but the voltage will be less than 13.8. It could be quite a bit less with a battery that big. Eventually the battery fills up to the point the voltage rises to 13.8 and the regulator starts reducing field current. Once the battery is around 1/2 full the charging current will taper off quite a bit. Like the old math problem where you get halfway to New York every hour, in the end you never can get there. It could literally take DAYS to get to 100% full at 13.8 volts with a small alternator and big battery.
Note the alternator HAS NO IDEA how full the battery is. All it is doing is trying to do it's best to hold 13.8 volts.

Originally Posted by High Hopes

Hi Joe,
This may be basically true for regulators in general, but not true for the regulator in my alternator. Maybe we talking about two types of alternator regulators? Is your alternator older? Have you measured the voltage over time? My readings do not show one constant voltage. - Steve

[joe_db]

PART III:
Better ways to charge:
You can get adjustable regulators, which I have one of, and set the voltage to what you want or get fixed regulators with different set points than 13.8. The good side is you can charge a LOT faster with 14.0 up to maybe 14.7 volts. The down side is too much voltage will ruin your batteries. I have found 14.0 as a fixed point works for gels and 14.2-14.3 works for wet cells and AGMs. You still have the "halfway to NY" issue, but not nearly as bad as at lower voltages. Note that you can set the regulator to 100 volts if you want and if the load from batteries or other onboard devices exceeds the output of the alternator, you won't reach the target voltage.

Even better:
"Smart" regulators, sometimes referred to as "3 step" or "3 stage", can be even better yet. They will charge at a high voltage, maybe as high as 14.2 for gels and 14.6-14.8 for wet cells/AGMs, and then back off to a much lower float voltage, say 13.2-13.5, to avoid damaging the batteries after they are full. Some of them work with temperature sensors on the battery and the alternator to back off charging if either one gets too hot. They get called 3 stage because they tend to follow this routine:
1 - Full field until the bulk charge voltage (higher one) is met.
2 - Back off charging current but hold bulk charging voltage until it decided the battery is full (called the absorption phase).
3 - Back off the voltage to the float voltage.

HOW it "knows" the battery is full is different for different regulators and some do it much better than others. I have one of these too but haven't hooked it up yet.

[High Hopes]

Hi guys,

I just got off the phone with a technical rep at API named Richard. I have the 55 Amp alternator Don Moyer sells, API model #20111.

According to Richard, the alternator has two modes of operation, ON and OFF. When the battery voltage drops below 13.4 volts, the alternator kicks ON. When the battery voltage rises to 14.6 volts, it shuts OFF, as in not on, nada, null and void, no power, zero output, I am sorry your call has been disconnected. It doesn't kick back ON again until the battery voltage drops to 13.4 volts.

Richard sounded knowledgeable and I got the impression that ON/OFF cycling has been the way of the world for decades. He has been working with alternators since 1968. According to Richard, alternators cannot run continuously without burning up. So they cycle in this way. When ON, the regulator controls the charge pumped into the battery according to an algorithm on a microchip which has been specified a battery manufacturer. The ON cycle has gone high tech.

So the alternator is really just a battery attachment. Who knew.

See you at the circus,
Steve

[Dave Neptune]

Joe, your spot on here. I'd like to add another view shall we say in support. The alternator has a max rating for it's output amprege and the depleted batteries can absorb lots of them (amps). All the regulator does 1-2or3 stage is try to maintain the "SET" voltage for a given regulator or regulator stage is set for. The regulator does not regulate output voltage or amperage it regulates the feed to the field to regulate "LOAD" on the alt or IT"S output level amperage which causes the bit of voltage fluctuations. The regulator regulates the field and voltage levels of the batteries demand the draw.
If you really want to get an idea of how an alternator works just unhook the regulator and hook the field directly to the circuit then you can control voltage levels with rpm and watch the voltage rise as the batteries become full.

Dave Neptune

[joe_db]

New one on me. I sold alternators and regulators for years and I never heard of any of them doing exactly that. This sounds like a 1/4-a55ed way to sort of do smart charging.

Originally Posted by High Hopes

Hi guys,

I just got off the phone with a technical rep at API named Richard. I have the 55 Amp alternator Don Moyer sells, API model #20111.

According to Richard, the alternator has two modes of operation, ON and OFF. When the battery voltage drops below 13.4 volts, the alternator kicks ON. When the battery voltage rises to 14.6 volts, it shuts OFF, as in not on, nada, null and void, no power, zero output, I am sorry your call has been disconnected. It doesn't kick back ON again until the battery voltage drops to 13.4 volts.

Richard sounded knowledgeable and I got the impression that ON/OFF cycling has been the way of the world for decades. He has been working with alternators since 1968. According to Richard, alternators cannot run continuously without burning up. So they cycle in this way. When ON, the regulator controls the charge pumped into the battery according to an algorithm on a microchip which has been specified a battery manufacturer. The ON cycle has gone high tech.

So the alternator is really just a battery attachment. Who knew.

See you at the circus,
Steve

[joe_db]

There is a device called an AutoMac that does just that. It is a switch on a timer that full-fields the alternator until the time runs out. Very dangerous if used improperly too

Originally Posted by Dave Neptune

Joe, your spot on here. I'd like to add another view shall we say in support. The alternator has a max rating for it's output amprege and the depleted batteries can absorb lots of them (amps). All the regulator does 1-2or3 stage is try to maintain the "SET" voltage for a given regulator or regulator stage is set for. The regulator does not regulate output voltage or amperage it regulates the feed to the field to regulate "LOAD" on the alt or IT"S output level amperage which causes the bit of voltage fluctuations. The regulator regulates the field and voltage levels of the batteries demand the draw.
If you really want to get an idea of how an alternator works just unhook the regulator and hook the field directly to the circuit then you can control voltage levels with rpm and watch the voltage rise as the batteries become full.Dave Neptune

[High Hopes]

Well,
I have seen the voltage changes at the battery when I run the engine and I have spoken with a man who represents the company which manufactured the very alternator I am using. He has 45 years of technical, not sales, experience with alternators and their regulators. His explanation, of what the regulator does, matches what I have observed. I think my API #20111 alternator is working fine.
- Later, alligators. -Steve

[joe_db]

Not saying it doesn't - never dealt with API. I dealt with Powerline and Balmar and went to the various classes and seminars back in the day by Heart Interface, Cruising Equipment, and Trace Engineering*. No one had regulators back then that acted like that. The stock A4 Motorola doesn't do that, my car doesn't do that, and none of the airplanes I fly do that.

*sales may be simplifying what we did. I didn't work at a car parts counter, I sold, designed, and installed high end electrical systems on boats.

EDIT - Looked through my old files. While none of the MARINE units I had ever did this, the poweline CAR unit does seem to vary between a high and low set point 0.8 volts apart. This would not do well with gel cells!

Originally Posted by High Hopes

Well,
I have seen the voltage changes at the battery when I run the engine and I have spoken with a man who represents the company which manufactured the very alternator I am using. He has 45 years of technical, not sales, experience with alternators and their regulators. His explanation, of what the regulator does, matches what I have observed. I think my API #20111 alternator is working fine.
- Later, alligators. -Steve

[High Hopes]

Hey Joe,
Thanks for responding. I have decided that the only way I can know for sure what is going on is to install an ammeter on the alternator lead. I will say that I can hear the engine RMPs drop just a little when I see the voltage go up, and visa versa.

Sorry about the sales dig. I'll catch you later when I have some actual current readings to go with the voltage points.

Cheers -Steve

[hanleyclifford]

Originally Posted by High Hopes

Hey Joe,
Thanks for responding. I have decided that the only way I can know for sure what is going on is to install an ammeter on the alternator lead. I will say that I can hear the engine RMPs drop just a little when I see the voltage go up, and visa versa.

Sorry about the sales dig. I'll catch you later when I have some actual current readings to go with the voltage points.

Cheers -Steve

http://www.defender.com/product.jsp?...6455&id=341907

[romantic comedy]

I have seen volt meters and ammeters for very cheap on ebay and other sites. Has anyone used these cheap meters?

[smosher]

Keep in mind that there will be voltage drop across the loop and it will vary with
a change of amps outputted from the alternator, more amps, more voltage drop.

On my wiring which goes from the alt to the amp meter in the cockpit to the
starter I will drop at 30 amps, a 1/2 volt. I have a sense wire connected to the common terminal of the a/b switch to the alternator. Which means that the alt
drives the a/b switch to 14.2 volts for my alternator which I believe is the api 20111 which sounds familiar, but I could be wrong. 30 amps is the most I can get out of the alternator.

Steve

[Administrator]

Those who are unsure of how an ammeter is used in a circuit, as opposed to a voltmeter, should (uh) read the instructions. I still have vivid memories of a pool of molten copper at my feet during a lab in engineering school.

Bill

[Marian Claire]

RC: I installed a cheap, 40$, set of three Sunpro gauges as a "temporary" set up in a slapped together mount. That was several years and 4000 miles ago. The volt meter gave it up about a year ago. The oil and temp are doing fine. YMMV. Dan S/V Marian Claire

[joe_db]

I made a whole panel out of FleaBay specials
As for measuring alternator output, there are at least two or three threads on here explaining the evils of the standard +/- center 0 ammeter sometimes found on A4 powered boats. You can read them for all the details, but to cut to the chase you need a shunt in the + lead from the alternator. Many electronic gauges have issues with + side shunts. I'll show you a link to a cheap meter and shunt that will work. Don't forget to fuse the shunt leads, they are on the hot side.
http://www.ebay.com/itm/New-Round-An...item2308cccc26

This thread - all 4 pages worth - is pretty good at explaining what meters go where and how to hook them up. http://www.moyermarine.com/forums/showthread.php?t=6702

Originally Posted by romantic comedy

I have seen volt meters and ammeters for very cheap on ebay and other sites. Has anyone used these cheap meters?

[High Hopes]

Just to make sure no one thinks I have gone completely daffy - here is a simple explanation of Current Regulation in the pre-alternator days of automobile generators. I have one of these electromechanical regulators kicking around my shop somewhere. I don't know if anyone remembers these guys - some coils had very think wires.

http://www.stinsonclub.org/PublicTec...r%20theory.pdf

Page 8.

CURRENT REGULATION

Besides the voltage being regulated, the current output (amps) of a generator is also regulated by what is called a current regulator. The current regulator is built inside of the voltage regulator and works in much the same way as the voltage regulator.
The main difference you will notice is that located on the inside of the voltage regu- lator, the current side of the regulator is made up of wire that is thicker (heavier gauge), and there are less turns or wraps of wire on the coil. Remember, the current regulator has to carry all of the amps the generator is producing.

OK, DO THESE REGULATORS WORK TOGETHER OR SEPARATELY?

They are unfriendly and will never work together. One or the other will do the work depending on the load. For instance, if the generator is spinning fast, the battery has a good charge, but most of the accessories are turned on, then the voltage regulator is the
one doing the work. If, on the other hand, the generator is turning slowly, the battery is in need of a charge, and all of the accessories are turned on, it will be the current regulator doing the work.

The voltage regulator and current regulator are units in the external circuit used to “sense” either high voltage supplied to the electrical system or high current supplied to the external loads. See diagram. . .

[romantic comedy]

I remember those regulators. My dad would open them up and bend something to fix it. It usually worked. I think it was the points on the coils inside. I do remember trying to fix a couple myself. I think I just cleaned up the points. Thanks for the memory. Long time......

[High Hopes]

Joe,
Classic looking meter you have there. It reminds me of the old sci-fi horror movies. I have a collection of old meters which I hope to put in a Frankenstein panel soon.

Igor! Throw the last switch!
No! Not the last switch!
Yes Igor, ALL THE WAY TO ONE HUNDRED!

[High Hopes]

My Class 1.5 voltmeter is only half a bubble off, assuming the meter from Sears is right.

[romantic comedy]

I know Don has some videos available. Does he have a charging and alternator one? Hint, Hint!!