Proper Voltage when Running?

[Polaris2007 4]

Guys, has anyone put a multi-meter on their battery when the engine is idling, and with the throttle all the way up? I am wondering what the voltage should read on my '77 C-120. I just got her up and running last night, and I want to make sure it is charging correctly. So if anyone has checked theirs at idle and full speed, could you post your results? Thanks again.......Jon H.

[Doubletrouble 10]

Since it is a 12 volt system I would think that while running you should have araound 13 to 13.5 volts while running at idle. The regulater should keep it in that range. I haven't checked mine myself (yet, now I'm curious) but that is typical on most 12 volt. I'm sure someone that has checked will be along soon. hope this helps.

[jpmcleod 4]

On my 77 C120 I have the factory voltage meter. It doesn't change from idle to fast. It goes up to about 13 after cranking and perty much stays there. On my other wheeh horses they do the same. On tow of my other brand tractors they both have a "battery condition" meter. They both stay around 12 to 13 when running at any speed. I may be wrong and someone will tell us, but as long as the battery meter reads 12 or 13 that means the battery is at full charge. All will run without a battery after cranking or a least they should.

[Polaris2007 4]

Houston, I think we have a problem. I just checked mine, and I'm showing 18.5 to 19 volts when the engine is at full speed, and around 17 when idling. Anyone know if this is typical if you have a bad rectifier? And I was thinking "Wow, these headlights are BRIGHT!!! Awesome!" Does it matter which way the two leads from the stator connect to the rectifier? I know the bottom terminal goes to the "R" terminal on the key, but the other two terminals on the rectifier don't matter right? :thumbs:

[can whlvr 994]

thats too much voltage,and it doesnt matter which way the stator wires go,could mean the rec is bad,do u have around 28 volts ac at the stator leads?

[TT-(Moderator) 1,162]

Connect a ground wire from one of the rectifier/regulator mounting bolts to the negative battery terminal and see what happens.

Mid 13 to low 14 volts would be ideal at WOT.

[Polaris2007 4]

TT, I did install a dedicated ground wire for the rectifier when i put the tractor back together. With all the body parts being freshly painted, I needed to do this to get a ground. Had to do it for the head and tail lights too. So I'm pretty sure I need a new rectifier. I see a used one on EBAY that looks just like my old one. Brand new they are $115 bucks! I also see some brand new ones on ebay for around $35, but these don't look like my older style. But the auction DOES list the Kohler K-series engines, including my K-301, as engines that it will fit. Anyone tried one of these "newer" style rectifiers on an older Wheel horse? Lastly, Can I just unplug the rectifier and run my tractor without it until i get the new one? Could this damage the stator in my K301? I'd like to just run the tractor off the battery until The new one arrives. Other than draining the battery, anyone see any issues with this? I JUST got her running, and I'm dying to go play a little.

[Save Old Iron 1,571]

There will be NO ISSUES with running the stator disconnected from the rectifier - just don't short the 2 stator wire together or to ground. Think of it like having voltage available from your house wall socket with nothing plugged into the socket. The electric company won't complain about that !

No problems should be seen running the tractor with just the battery. I would be curious on how long the tractor will run on just a battery charge. With lights on I'm guessing over 2 hours ????

Some tractors do have a warning label not to run the tractor without the battery connected. These are generally the tractors with engines that have "electronic: ignition modules that will suffer from erratic voltage at their inputs.

[Polaris2007 4]

Can,

I just checked and it's hard to get a good reading because my digital multimeter is kinda slow to respond because it is 10 degrees here, but when i tested the stator leads, I'm showing about 24vac idled down as low as it will go, and it looks like about 45vac at w.o.t. But it's hard to tell, the meter is all over the place......

[Save Old Iron 1,571]

polaris,

24VAC is perfect.

24 VAC means half the wave is +12v and the other half of the ac wave goes down to -12v so total AC voltage between these two peaks = 24vac.

So the rectifier chops off anything in the negative region, only lets the positive part of the AC wave thru and produces about +12 volts to the rectifier assembly. In the world of electronics, you would multiply the AC voltage by 1.414 when you use a filtered / rectified supply. The rectifier does just that and the battery acts as a very very good filter capacitor and removes virtually all the ac ripple and leaves pure DC.

So the stator output should be capable of producing in excess of (12 x 1.414) DC volts or around 17 volts DC which is then regulated down to 13 - 14 by the regulator part of the rectifier / regulator.

When your stator is off idle and the stator output is 40 VAC , rectifier cuts it in half (20VAC) filter makes it DC (20 x 1.414) or 28VDC which the regulator then cuts down to 13 - 14 volts DC.

That's why when a regulator shorts, the battery voltage has the capability of going very high (17 - 18 V DC).

The slow response you see on your meter (most likely a digital meter) is actually frozen "gel" which forms the LCD readout of the meter. When the "gel" freezes or gets very cold. its reaction time to updates slows waaaayyyy

down. An analoge meter or one with LED (not LCD) technology will read much better at cold temps.