Generator AVR

[a64pilot]

You can get a Kill-A-Watt meter for less than $20.
I leave one plugged in all the time, it tells you voltage, frequency and consumption. So it’s good for telling you exactly how much current something draws over time as well as a very accurate voltage / frequency meter.
https://www.homedepot.com/p/Kill-A-W...FVAqhwoddu0B5g

My generator ran a little low on voltage too, like 105 or so when it was 60hz under load, I changed the capacitor uf value by 5 and that brought it back to right at 120 V at 60 he and 3/4 load.
But first as has been said you need to get the Hz right. To be at 60 Hz under load, I have to set mine to run at about 62 or 63 Hz when not under a load, the Governor isn’t perfect.
When it gets close to max load, the motor slows on mine, which of course cause the amps to go up, which drops RPM, which causes the amps to increase, it’s a viscous circle.
Mine will run at about 27 amps continuously before it gets into the RPM drop, amp increase circle and it then over amps. (it’s a 30 amp machine)

[Ding Duck]

The reason why the Voltage is much better with the Hot water is due to the Power Factor. the Hot water element is purely resistive and has a PF of 1 (unity). When you run the A/c, this will have a lower power factor say 0.8 because of the induction motor in the compressor. Power = Volts * Amps * Power factor. Unfortunately, the problem with Cap regulation is not very good regulation of the Voltage. The generator works on a Volt/ Hertz ratio, so increasing the speed will increase the voltage. Generally it is the same engine/Gen configuration for 50 or 60 Hz, so there may be 'High Idle' adjustment (Stop Screw) where you can increase the revs. Just remember, you will increase the Voltage at no Load, so make sure this is not too high. You may just need to find a happy medium. A 3% droop (droop = difference of No Load to Full Load) is not uncommon for the engine.
Cheers
Sorry, just noticed A64Pilot comments and he makes a good point on changing the Cap value. Should also work for you

[sailorboy1]

Originally Posted by sailorboy1

My generator has a capacitor for voltage control and when loaded the voltage drops a lot. Does anyone know it it is reasonally possible to change it to an AVR or even a manual one?

So I've checked and measured speed (Hz) and yes it slows down, but not enough for the amount of voltage drop I'm seeing. I have tried the speed governor at both stops with basically the same readings and even replaced fuel filter just in case they were causing a slowdown.

Still have the voltage problem after about 60% rated load.

So I'm still looking to see if anyone has experience with the original question.

[DotDun]

Originally Posted by sailorboy1

So I've checked and measured speed (Hz) and yes it slows down, but not enough for the amount of voltage drop I'm seeing. I have tried the speed governor at both stops with basically the same readings and even replaced fuel filter just in case they were causing a slowdown.



Still have the voltage problem after about 60% rated load.



So I'm still looking to see if anyone has experience with the original question.

I bumped my capacitors up by 5mf, it bumps the top voltage plus holds voltage within 10% over the full amp-draw range.

The problem with electrolytic capacitors is the dielectric drys out, the more heat the faster they dry out. Of course cheap ones from China are well, mostly junk. I moved my capacitors out of the alternator case to a spot inside the sound shield, they are cooler and can I change them in 2 minutes and a new wire tie.

If you buy new capacitors, measure them before using, I’ve bought 35mf that measured 55mf.

[a64pilot]

How much RPM drop?
I ask cause right at about 57 Hz my voltage seems to fall off a cliff.
I just ran my generator today and with a 20amp load, it was running at 59.7 Hz, close as I’m going to get it. I did have to adjust my generator arm to get to back to the correct speed.
It runs under no load at about 61 Hz, maybe just under 62 Hz.

Once you get the RPM correct, I see no other choice than to change Cap value. I got mine off of Amazon.

I think it takes a special multimeter to measure a capacitors UF value if I’m not mistaken.

My little motor is about all in at around 28 amps, it can’t quite make 30.
Actually it can, but what happens is the RPM drops so that the voltage drops, which raises amperage of course, so it’s not making any more watts, but amperage does go up.

[a64pilot]

Hook your multimeter up to the generator to measure voltage and put it under a load, then manually move the Governor lever to get it back to 60Hz and see if the voltage recovers.
If it doesn’t, change the capacitor value, Id try changing by 5

[sailorboy1]

Looking at the spreadsheet I put the readings in, yes the voltage really drops at about 57hz. So I guess changing the cap value is an answer. But if I am going to do something like this I would be interested in a better control system if possible. Which takes me back to post #1

[a64pilot]

Originally Posted by neworleansrich

What type of generator?



Several AVR's are available off the rack. I am in the process of changing out an aftermarket AVR in a Westerbeke 8kw that has become intermittent when it heats up. Just 2 120v wires, 2 field wires, no big deal, but you need an AVR that matches your field voltage range. The field voltage on that unit is in the 10-12v range. Marathons are more like 60-70v.



PM me and I'll give you the phone no of a guy in Miami who can probably get you the right one.

I think this is your best option then.

[DotDun]

Originally Posted by sailorboy1

Looking at the spreadsheet I put the readings in, yes the voltage really drops at about 57hz. So I guess changing the cap value is an answer. But if I am going to do something like this I would be interested in a better control system if possible. Which takes me back to post #1

(2) capacitors = $20
AVR = $200-$400

Capacitors last 1-2 years. Caps are easy to purchase/find/spare, easy to change - AVRs, not so much.

AVRs rated to keep voltage range within 5%, capacitors 10%.

YMMV

[sailorboy1]

Originally Posted by DotDun

(2) capacitors = $20
AVR = $200-$400

Capacitors last 1-2 years. Caps are easy to purchase/find/spare, easy to change - AVRs, not so much.

AVRs rated to keep voltage range within 5%, capacitors 10%.

YMMV

Cost difference is not a reason to not go the AVR to me.

[a64pilot]

Originally Posted by sailorboy1

Cost difference is not a reason to not go the AVR to me.

Once you get it installed let us know how it works, although I think you can get what you want with a different Cap value. It worked for me.
Funny thing was when I removed the original Cap, it was slightly lower value than spec, leading me to believe that they may “tune” them to voltage output by varying the Cap value, or of course maybe they just out the wrong Cap in at the factory.

[sailorboy1]

Hell I still trying to find out if it can be done. That's the thread topic!

[a64pilot]

Did you PM the person that said it could be done? He offered to give you a contact to buy one.

[Sailmonkey]

Originally Posted by sailorboy1

Hell I still trying to find out if it can be done. That's the thread topic!

It’s not looking good.....here’s something that makes sense to me.

http://listerengine.com/smf/index.php?topic=6477.0

[sailorboy1]

Originally Posted by Sailmonkey

It’s not looking good.....here’s something that makes sense to me.

http://listerengine.com/smf/index.php?topic=6477.0

Yes I've seen and read that thread. But, as it is just an internet forum response it suffers from being reliable to me plus it's the only thread I have come across that says this. I've sent the question and schematics off to a more reliable (I hope) source.