Voltage regulator Bob M and/or others

I would like to get a short course here on voltage regulators. My generator is working at 8 volts and charging up to 20 amps at full throttle less as I go slower. I believe it may have destroyed my fairly new battery (thank goodness for warranty)..I have a Tisco 6v pos ground VR. Taking the cover off I dont see anything that adjusts. There are two coils with points, one open and one closed. Can you tell me about what I see? Thanks Henry

Bob M or Bob or Jim n others can correct my errors, but heres my take on what you have n see.....

EASY ONE FIRST The one "coil/relay" is a Cutout Relay which closes (between BAT and GEN/ARM terminals) when the gennys ARM output voltage is higher then the battery but opens otherwise so the battery cant reverse discharge thru the genny when shes shut down. Its has both a Shunt and a Series winding.

The other "coil/relay" is likely a current control regulator which increases or decreases the gennys Field current as necessary to charge but NOT overcharge the battery (if adjusted n working correct that is???). It does so by switching and/or via pulse width modulation (chattering) to add or remove extra resistance into the field to ground circuit thereby increasing or decreasing the gennys output.

Some 2 coil VR's (what you have) use a combination Voltage n Current control relay while others (my guess what you have) use just current ORRRRRR voltage control. The 3 coil relays have a Cutout Relay, a Voltage Controller, and a Current Controller. Im guessing you have a current control relay becauseeeeeeeeeeee if it was a voltage control relay it needs adjusted to work at 8 volts buttttttttttt I take it yours hasnt been adjusted right???

As I understand it, On the 2 wire cutout relay systems you can charge an 8 volt battery with no modifications..........If you have a 2 coil relay that has a current controller, again it can charge at 8 volts no mods,,,,,,,,HOWEVER if you have a VR that uses a Voltage Controller relay, it needs adjusting to charge an 8 volt battery otherwise you may not charge it correct n maybe RUIN the battery.........

If a battery is overcharged it will outgas excessive and/or boil over n self destruct, maybe you need a VR adjustment so depending on what type VR you have, you may be able to PROPERLY charge that 8 volt battery

Until corrected thats my story n Ima stickin to it lol

John T

All that makes sense except I had a 6 V battery that was fully charged at 7.4 volts according to my meter. So------ I either need to get a 8 volt battery($$$$$) and or adjust the VR. I cannot see any place to adjust anything. How do you do It Thanks for your help Nuff said Henry

Henry - Expanding a bit on John T''s comments, 8 volts is indeed too high - 7.0 to 7.3 is the max a 6 volt battery should be seeing.

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Inside the regulator, voltage is controlled by the voltage/current regulator relay - the relay with the normally closed contacts (ie. the one with its contacts held SHUT by spring pressure).

Voltage is adjusted changing spring tension on this relay. And spring tension is adjusted by bending the fixed hanger on the regulator relay: higher spring tension = higher voltage.

In your case you need to bend the spring hanger to reduce the spring tension. But proceed VERY carefully - only takes a slight change in spring tension to significantly change the voltage!

Hope this helps!

Also, disconnect the battery BEFORE removing the metal cover from the regulator. It's REAL easy to let all the smoke out, if you don't!

Henry - If the tractor were mine I'd put a crowbar in my wallet, purchase a new regulator and be done with it (will cost you less than your next replacement battery!)

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That said, and if you still feel like messing with it, the regulator relay is adjusted by gently bending the spring hanger. It is best accomplished with pair of small needle-nosed pliers. Here's how I've done it:

Make sure the battery is fully charged. Remove the regulator cover. Place a DC voltmeter across the battery. Start the engine and run it at full governed RPM for a couple minutes before proceeding.

Now VERY CAREFULLY grab the regulator spring hanger with needle nose pliers (don't touch anything any other metal with the pliers!). While observing the voltmeter, bend the hanger very slightly to reduce the spring tension.

When the voltmeter reads 7 - 7.25 volts, stop! Let the engine run a minute or two and check the voltmeter reading again. If it's not 7 - 7.25 volts go back and bend the hanger again as needed. It may take several tries to get it to spec.

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As I mentioned before regulator setting is a fussy, sensitive adjustment. And as "Bob" points out above, one slip with the pliers and the smoke will come out of the regulator - you will wind up buying a new regulator anyway! (Don't ask how I learned this....)

OK, got all that. The next question is why does it not cut out when the battery is charged but I just realized that since it is charging at 8 volts it probably doesnt recognize full charge and just keeps turning out the amps. What Say? Thanks a lot Henry

"The next question is why does it not cut out when the battery is charged but I just realized that since it is charging at 8 volts it probably doesnt recognize full charge and just keeps turning out the amps"

Henry - That's says regulator relay is outta whack - that it is regulating at too high a voltage.

The regulator relay winding senses system voltage. When its set voltage is reached it pulls the regulator contact points open. This interrupts current flow to the generator field which causes generator output voltage to fall. When system voltage drops below set voltage the regulator points re-close, field current to the generator builds and output voltage again increases.

This open/close cycle repeats very rapidly (10 - 15+ times a second) causing the generator output voltage to stabilize at the regulator's set voltage.

Also the points open just enough (a couple thousands of an inch) to break the field circuit. So unlike the cutout relay, you cannot tell whether the regulator is working simply by looking at it.

Make more sense now?

Yes it does. Wow, I asked for a short course and got it. I now understand the VR. I am going to attempt to adjust it this evening . Wal-mart had to order a new 6v battery for me as the old one was warranteed. It came in this morning. I am very much considering going to an 8 volt battery since I only use it for starting and lights. What say you to that Idea. Thanks Henry

Henry - Forget about the 8 volt battery! They're expensive and they tend not to last very long. Also if you use your lights much you'll find they won't last very long on an 8 volt diet. (However the lights WILL be delightfully bright until they burn out...!)

Further, if your regulator is bad there's a good chance it'll simply cause the generator to now pump 10 - 11 volts into your spendy new 8 volt battery - leaving you right back where you started.

My advice: Stick with the stock 6 volt battery and get that regulator working like it's supposed to!

Adding to Bob M's great advice, I will ask you to get a second opinion on your volt meter. A wrong reading meter will make all your adjustments wrong. 6v batteries are not really capable of more than 6.3 to 6.5 volts while sitting W/O being charged. Maybe in the first minute after a high rate charge, but not 15 minutes. Digital meters are not as good as modest cost meters with a moving needle for these old machines! JimN

Good advice Jim! A reading of anything greater than 6.6 volts on an idle 6 volt battery would make me suspicious of the voltmeter calibration.

Also unless you've got a high quality, industrial grade digital voltmeter you are better off with an analog multimeter when working with old tractor electrics. The transients and noise from generator commutators and vibrating relay regulators can drive low-end digital meters to wildly erroneous readings.