Coleman Powermate low voltage

[Pumbaa]

Hello, Forgive me if this post is Off Topic, I cannot seem to find any sort of generator newsgroup, I posted this on alt.rv but I have not had any responses...

I have a Coleman Powermate 1850 MegaPulse Generator Model PM0401853 which I am trying to help my father-in-law fix. Unfortunatley I don't have any sort of tachometer to check the speed but it starts easy and sounds right and I really don't feel that there is anything wrong with the gas motor itself.

So, I assume that my problem is in the generator side of things, it will only give me about 90 Volts @ 60HZ. Because the Hz is right I assume that the RPM's are correct, so why am I only getting 90 Volts?

If I manually overspeed the motor (and it really sounds like it is running too fast when I do this) I can get 120 Volts BUT the frequency is about 70 Hz (which again leads me to beleive that the engine speed is too fast). This is frustrating because if I had a bad diode or a bad winding I would think it would not work at all. But I cannot think of a reason that I would get low voltage at (what I assume to be) the correct RPM.

Some research on the internet let me to un-solder the diodes on the rotor and according to my voltmeter they are okay. What I need to know is what Ohm readings I should get on the rotor windings as well as on the different windings in the stator. Also, according to my voltmeter the capacitor is okay. The only manual I can find for this generator on the internet is the owners manual. Anyone with a techical manual for this generator perhaps you can help out...

Thanks in advance

Craig

** Follow UP** the folks at Powermate think it is a diode problem (unless I am using my voltmeter wrong, I already checked them).

[Steve Stone]

What kind of meter are you using to measure the voltage? Does it measure the correct voltage level from the power company? Could the meter be confused by the saw tooth or square wave out put of most gensets vs a pure sine wave?

Steve

[HeyBub]

Does the voltage remain low when connected to a load?

[Chip C]

And what are you using to measure the frequency? There aren't a lot of home-handyman instruments that measure frequency. I'm also thinking that your measurements may be misleading because of waveform.

What is it that leads you to suspect that the unit has a problem? Do things not work when they're plugged into it?

Chip C Toronto

[Pumbaa]

I'm using a Craftman Digital volt meter for the voltage. And a P3 Kill A Watt for the frequency (I don't have anything else to read frequency)

[Pumbaa]

Good question. In fact the voltage reads 0 until it is connected to a load. As I understand it, this is due to it being a brushless style generator.

[ransley]

Try alt.energy.homepower many there know generators, but if its

60hz, rpm is probably correct at 3600.

[Pumbaa]

I'm learing a lot here, thanks for that. As for the sine-wave problems I have no idea how to address them. I have been using a digital volt meter to check everything (except the frequency), I have an older analog meter that I can use if that will yeild different results. The ONLY thing I have that shows frequency is a little electricity use gizmo called a KILL A WATT, not as good as something else but it is the only thing I own that shows frequency. As for things working right, any sort of light bulb seems dim (I have been using a 300 watt shop light for testing purposes). The generator is a brushless style and in fact won't show any voltage until I place a load on it, so I plug the light in one socket and my DMM probes into the other. I am hesitant to start pluging stuff in if it is not working right, I don't want the low voltage to dammage something (but, maybe it wont).

[bob haller]

=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD =EF=BF=BD C= raig

the generator is probably low voltage cause engine running slow, they are VERY noisey at running speed. frequency of square wave probably confuses kill a watt.

I bought one of these generators for 50 bucks off craiglist for a buddy of mine. he adjusted one govenor spring that was stretched and it warks fine

try some standard light bulbs to test voltage.

frequency doesnt matter for most stuff but does mess with clocks etc

[Stormin Mormon]

Some inverters put out modified sine, which reads about 90 volts on a digital meter. My suggestion is try a filament lamp of some kind, or maybe a hair dryer. Old style toaster, is also good. If the toaster works, you're likelly getting modified sine. And the machine is OK.

I have an ETQ which has really done a good job. Never checked the voltages. It runs a toaster (Yes, I really did plug in a toaster, and try it.) Also runs a furnace, guy I knew had his power out, couple years ago. The ETQ ran his furnace nicely.

[Stormin Mormon]

That's why I suggest a cheap toaster, or a lamp with filament bulb. My guess is, you're over analyzing the problem.

If you don't think you're over analyzing, I'll give you several other options.

[HeyBub]

Ah, good catch! If the generator is putting out a modified sine wave and the meter is measuring peak-to-peak, there's gonna be a difference.

[Ulysses]

I'm learing a lot here, thanks for that. As for the sine-wave problems I have no idea how to address them. I have been using a digital volt meter to check everything (except the frequency), I have an older analog meter that I can use if that will yeild different results. The ONLY thing I have that shows frequency is a little electricity use gizmo called a KILL A WATT, not as good as something else but it is the only thing I own that shows frequency. As for things working right, any sort of light bulb seems dim (I have been using a 300 watt shop light for testing purposes). The generator is a brushless style and in fact won't show any voltage until I place a load on it, so I plug the light in one socket and my DMM probes into the other. I am hesitant to start pluging stuff in if it is not working right, I don't want the low voltage to dammage something (but, maybe it wont).

I typically use (used to anyway, until it said "PF" and then nothing) a Kill A Watt to check the frequency of my generator before connecting them to my OutBack inverter system which will refuse to connect if the frequency is out of range (about 56-64 Hz, thereabouts). I typically set the frequency to about 63 Hz and it generally drops to about 59-60 when a load is applied. The generator you have is rather pathetic (I have one too) and if I recall it only ever put out about 100 VAC at anything over about 1000 watts. If you ask me they are lying about the output. If the diodes check out OK and the field and stator coils are not open then I suggest increasing the engine speed until you get 63 Hz which will probably be around 130 VAC. Until you attach a load.

The good news is that for half the money you can get a cheap Chinese generator (UST GG2300) that really does produce 2000 watts and lasts about

10 times as long. It's a little bit bigger and noisier though, but not real loud.

[The Daring Dufas]

The frequency of the AC power is determined by the number of poles the genset has in relation to the speed. A two pole generator runs at 3600rpm whereas a four pole generator runs at 1800rpm. The output voltage is determined by the field voltage supplied by the voltage regulator. The field voltage may only be 12 volts DC to get the generator to output 120VAC. A small change in field voltage produces a large change in output.

TDD

[Pumbaa]

WOW, Thanks for all the response folks! Just to clear up some stuff, it is a two pole rotor so I believe I need 3600 RPM. Second, (unless I am really up in the night) there is NO inverter in this baby, it generates AC. It sounds like (particularly from people who have owned them) that there may be NOTHING wrong with it which is kinda' sad. Well, I am going to go out and tinker with it some more...

[Doug Miller]

Just one question: are you measuring the voltage under load, or under no load?

[Pumbaa]

On this gen, you don't get ANY voltage unless there is some sort of load... I have been using a 300 Watt shop light (just 'cause it was handy)

[Pumbaa]

Latest and Greatest.

Okay, I un-soldered the diodes and checked them one more time, good to go. Put the whole thing back together, and fired it up. Same problems, If I want 60Hz I get about 90 volts. If I want 120 Volts I get about 70Hz. (In my house for comparison the Kill A Watt shows 59.9Hz and 122.0 Volts) Just to see what would work, I tried hooking up my table saw, it took a second but it did spin up and I am sure that baby pulls some amps! I then tried my battery charger, no luck it would not even turn on (which is kind of the reason I want this gen anyway). And on the 12 Volt socket I get 24 Volts!!! I'm not out any money here, just time. But, after I burned my thumb on the exhaust trying to tweek the rpm's I decided enough is enough. If I had a shotgun I would end this units pain and suffering...

Thanks to everyone who posted Craig

[Ulysses]

Why would a single phase generator be putting out a square wave? I imagine it may be somewhat fuzzy, but I think it pretty much has to be a sine wave.

[Ulysses]

I actually bought a new engine for mine (the first one didn't last very long) and it just never seemed to have enough output. I even tried connecting it to a 4 HP Honda engine. I broke the cooling fan on the rotor when I connected it to a 10 HP engine, just to see if the low output was due to not enough engine power. I found another use for that Honda engine and I'm looking for another use for the replacement engine (compressor perhaps?). I replaced all the diodes, checked the resistors, checked the coils, and I just can't find anything wrong with it. Come to think of it, you may have a bad capacitor. That might cause the low frequency. Make sure you get one with the exact same value. It should at least get a battery charger to come on (assuming it's a high-frequency smart charger type). Your DC voltage seems a bit high but I wouldn't be surprised to see

17 or 18 volts. For emergency battery charging only.

BTW Coleman gets about $250 for a new rotor. The cooling fan on my cheap Chinese generator starting falling apart (at 3000 hours) and they only want $25 for a new rotor. The whole generator usually sells for about $250 (or less on sale). My Coleman engine only lasted about 300 hours.