Generators and low voltage - Again!

belfert · September 17, 2020, 09:35:31 AM

I had to replace the regulator on my 8KW Powertech generator because I blew it out. The replacement regulator was set to 148 volts! I adjusted it down to 127 volts. Anyhow, my issue is it starts at 127 volts with no load and the voltage drops pretty fast after that with a load on it. By the time I put three 1,500 watt heaters on it for a total of 4,500 watts the voltage was down to 107 volts! I talked to Powertech support and he seemed to think that is normal. The only thing he said is to check the hertz.

I had a conversation with Jason (I think that was the name) at Wrico today about just replacing this generator next summer for something better. He says his generators will stay within a few volts. Nothing like a 15% to 20% drop like the Powertech.

Utahclaimjumper · September 17, 2020, 09:50:47 AM

If the RPM drops with the increased load,, then that's your problem.. The RPM is needed to maintain 60 hertz..>>>Dan

chessie4905 · September 17, 2020, 11:45:36 AM

You dont have a fuel filter starting to get plugged? Is the engine governor mechanical or electronic? Does your generator head have brushes? Are they in good condition?

belfert · September 17, 2020, 12:55:33 PM

Fuel filter has about an hour on it, maybe two hours. I replaced it right after my last trip.

The hertz is a funny thing. My meter has a kilohertz readout. My power from the power company reads .060 KHz or 60 Hz. The generator with the breakers on the generator off reads something like .490 KHz or 490 Hz. I suspect the problem is my meter because everyone I have talked to says that there is no possible way to generate that many Hertz as it is RPM dependent.

luvrbus · September 17, 2020, 01:29:52 PM

That is not normal my ONAN 12,500 will only drop 1 volt with 3-15000 AC units running,buy you a cheap non contact hand held tachometer and check the RPM drop under a load, to me it sounds like the governor is not sensing the load on the little CAT engine .PowerTech is not the greatest generator but they are not all that bad

seafarer · September 17, 2020, 01:42:00 PM

Get a hold of a VOM that has a Hz function. Test anywhere you have an outlet.
You should be seeing 60-61 Hz at no load. At FULL load no less than 57 Hz.
The difference in no load to full load is referred to as "droop" and is usually expressed as a percentage. 5% droop is normal for this setup.
So for every 30 rpm = 1 Hz. 1800 rpm = 60 Hz.
The voltage is a result of excitation and should not drop more than 5-8 volts from no load to full load as long as
the engine can supply the needed power.
Besides the fuel filter the air filter may not be allowing the engine to produce full power. Quick test is run engine without it. Is exhaust system
free from blockage/debris?
Fuel delivery may also be culprit. Try running engine out of a 5 gallon bucket right next to engine.
From memory Powertech used to use Isuzu engines and Stamford-Newage alternators. Both decent names. (I have an 8kw with that setup
and the Isuzu is practically bulletproof)
Lastly, your injectors could be fouled, sometimes a result of running with too little load or a load of crappy fuel.
I would exhaust every last possibility before replacing the unit and discovering a collapsed hose or something similar.
Hope this helps.

belfert · September 17, 2020, 01:48:11 PM

The fuel and air filters were both replaced after my last trip and have maybe two hours on them. Things got a fair bit better after replacing the filters.

I do have a meter with kilohertz on it. It reads .060 KHz for my shore power, but something crazy like .490 KHz for my generator with no load.

chessie4905 · September 17, 2020, 03:52:08 PM

Check all big connections inside control box of generator for loose or burned connections.

buswarrior · September 17, 2020, 05:15:52 PM

Get a "kill-o-watt" meter.

Besides all sorts of good busnut load measuring, it also reads Hz.

Best, cheapest tool a busnut can buy towards one's electrical planning and measuring efforts.

Happy coaching!
Buswarrior

belfert · September 17, 2020, 07:22:09 PM

Quote from: chessie4905 on September 17, 2020, 03:52:08 PM
Check all big connections inside control box of generator for loose or burned connections.

I had already checked all of the connections for tightness before some of these issues popped up.

belfert · September 17, 2020, 07:41:55 PM

I will get a Kill-A-Watt at Harbor Freight tomorrow. I really don't think the hertz is as high as my meter shows or everything electronic like the inverter would have blown up.

luvrbus · September 17, 2020, 07:49:55 PM

Take it to CAT dealer they can tell you in a few minutes if the engine is producing enough hp for the generator head you can spend lots of money and still be looking for answers didn't we go through this a couple of years ago ?

belfert · September 18, 2020, 04:43:48 AM

I am about 75% certain I am going to get a Wrico generator next spring and junk the Powertech. I talked to someone at Wrico and they assured me their voltage wouldn't drop like the Powertech.

chessie4905 · September 18, 2020, 06:53:12 AM

So...your Powertech has done this since new? How many hours? Does the head use brushes?

luvrbus · September 18, 2020, 07:11:26 AM

Quote from: belfert on September 18, 2020, 04:43:48 AM
I am about 75% certain I am going to get a Wrico generator next spring and junk the Powertech. I talked to someone at Wrico and they assured me their voltage wouldn't drop like the Powertech.

Changing you will need to build your own quite box,I don't think Dick offers that option,it is not going to be a plug and play,On the Country Coach owners forum people are not happy with the PowerTech either,you have a advertiser here EPS that builds a darn good generator