Champion Generator not even close to rated output

[CapnCampn]

Continued from here:
http://www.rv.net/forum/index.cfm/fuseaction/thread/tid/29788443/gotomsg/29792553.cfm#29792553

I have a Champion Non-inverter 3500/4000W generator that isn't putting out it's rated output - I've tried running 2 1500W electric heaters on it, and it will bog down and die.

The Gen is model C46540

I did email Champion about the issue, and they had me run electrical checks on the generator side - everything seemed ok, so it appears to them (and me) that it's an engine/hp issue.

I'm at about 2500ft, and they say that the generator will be down about 300 watts at this altitude, so should sustain 3200 watts.
My testing was done with a kill-a-watt and various combos of hi/low settings on the heaters As BFL found, once you get a ways above 1500W, the kill-a-watt starts to complain. I think all the numbers in the table below were from the Kill-a-Watt.

I tested the output with a couple of electric heaters plugged into a power strip using the 5-20R receptacle (not the TT30).

This was at the end of a 40' 12Ga extension cord (it was raining a bit so I wanted to be under cover), using the Kill-a-Watt & combinations of 2 electric heaters with hi/lo settings.

Watts Volts Hz
21 119 64
750 117 61
1220 116 59
1370 116 59
1420 116 59
1930 115 58
2050 115 58
2330 113 56

At the 2300W range, the engine on the generator was working really hard, and starting to lug - you can see this in the frequency column. At one point, it was about to die, and the kill-a-watt actually reset. I turned off a heater before the engine died though.

I feel that this load shouldn't be a problem since it is only ~66% of the generator's rated output, and these are mostly resistive loads (both heaters have small fans of course).

The temp was ~60 degrees, and I am at 2700ft elevation.
I thought maybe it had something to do with using only the 5-20R, but the schematic in the manual shows that both 120V outlets are paralleled, so they should be able to provide the same power, limited by the receptacle specs. The engine/generator shouldn't care which one is being used.

From the engine side, the gas is not new, but has had stabilizer in it, and the oil only has about 2 hours on it. I think I adjusted the valves the spring before last, but I can’t remember for sure. The Spark arrester is clean.

I'm not sure what else to check at this point. Generally it does what I want it to do, but it's a little disappointing that it won't do at least 3KW.

[DrewE]

BFL13 wrote:

LScamper wrote:
Long cord lowers load not increase it.
High altitude equal less air but same amount of fuel equal rich mixture.

Years ago I didn't understand when you told me current limiting was a way of keeping current constant. I thought you needed a way to keep the current up too. Later I got that.

So now I an stuck on how a longer cord (more R?) is less load.

Your heater or whatever on its own has a resistance R. Your longer cord adds a bit, for the resistance seen by the generator of R + a bit. Since the generator output voltage is supposed to be constant, by ohm's law the current (and hence power) is lower.

More generally, for a constant voltage source, the applied resistance is inversely related to the load. The minimum load is an open circuit, with no power being consumed; the maximum theoretical load is a short circuit with infinite power being consumed...but of course in real life you can't supply or dissipate infinite power, so something somewhere gives out, possibly with spectacular results.

[PaulJ2]

BFL13 wrote:
Are you saying at high altitude, with the kit, it is getting the proper mix, but not enough of the mix to maintain the revs needed to keep the 120v up?

Yes, that is a very good way to put it. If only you could put a turbo on that thing!

[BFL13]

Are you saying at high altitude, with the kit, it is getting the proper mix, but not enough of the mix to maintain the revs needed to keep the 120v up?

[PaulJ2]

"High altitude jet kit" is to keep the RATIO the same, not the amount of fuel.
Octane is only a measure of how fast the fuel burns. Higher octane slower burn rate, lower octane faster burn rate/flame spread.
High compression engines need slower burn rate to prevent "pinging".
The higher power is generated with the higher compression not the high octane fuel. If you get the compression high enough you will have a Diesel engine.
These are ignited by the heat only from the extra high compression.

[BFL13]

Ok, so change "air" to "oxygen" and now you want less fuel for the same "mix" up high.

"Less fuel" can mean either less jetting at the same octane, or same jetting at less octane?

I missed where the engine can't maintain the same revs needed to "rotate the field" as long as it is getting the required mix.

[LittleBill]

BFL13 wrote:

LScamper wrote:
Long cord lowers load not increase it.
High altitude equal less air but same amount of fuel equal rich mixture.

Years ago I didn't understand when you told me current limiting was a way of keeping current constant. I thought you needed a way to keep the current up too. Later I got that.

So now I an stuck on how a longer cord (more R?) is less load.

Meanwhile, on jets, is a "high altitude kit jet" supposed to keep the fuel the same as at sea level? Why would amount of fuel change going higher? Or is the amount of fuel the same in the mix but for less octane?

Whatever you atomic bomb guys say! I do try though. 😞

Oops now we have same amount of air but less oxygen in it going with same gas but less octane so you need more -- I lost it, drat!

Please don't give up folks. I will get it eventually if hit on the head with a 2x4 or two.

its pretty simple.

higher you go less air

less air = less fuel to get correct ratio

high altitude jet = less fuel to = less air

the engine is losing power regardless.

the jetting just stops the engine from running too rich (same as if the choke was on)

[BFL13]

LScamper wrote:
Long cord lowers load not increase it.
High altitude equal less air but same amount of fuel equal rich mixture.

Years ago I didn't understand when you told me current limiting was a way of keeping current constant. I thought you needed a way to keep the current up too. Later I got that.

So now I an stuck on how a longer cord (more R?) is less load.

Meanwhile, on jets, is a "high altitude kit jet" supposed to keep the fuel the same as at sea level? Why would amount of fuel change going higher? Or is the amount of fuel the same in the mix but for less octane?

Whatever you atomic bomb guys say! I do try though. 😞

Oops now we have same amount of air but less oxygen in it going with same gas but less octane so you need more -- I lost it, drat!

Please don't give up folks. I will get it eventually if hit on the head with a 2x4 or two.

[PaulJ2]

As you go up in altitude there is also less oxygen in the air. So to keep the air/fuel ratio the same less fuel is needed.

[LScamper]

Long cord lowers load not increase it.
High altitude equal less air but same amount of fuel equal rich mixture.

[BFL13]

jplante4 wrote:

theoldwizard1 wrote:

EDIT : Newer small engines are set to run right on the edge of "too lean" in order to meet emissions. I would install the high altitude jet any way.

If it's running lean at sea level, an increase in altitude will enrichen the mixture.

I can't get my brain around this. At higher altitude you need less of an octane gas than at lower altitude. (according to my gen's manual)

At higher altitude air pressure is lower.

So what is going on there with "mix" (rich vs lean) as you go higher?

Thanks (unless it will make by brain hurt more )

[PaulJ2]

You have an engine problem not a generator problem. As mentioned plugged air filter, throttle/governor not opening all the way. Possible wrong jet in the carburetor? Maybe has the lean high altitude jet in already? Larger jet, more fuel, more power. Look there.

[CapnCampn]

Wow, lots of input!

I'm not ruling out fuel, that's why I chimed in on BFL13's Octane thread too.

The Voltage regulator is brand new (and sealed, I don't remember a pot on it), I replaced it after I got the gen (which was a very good price - I've gotten way more than I paid for Cummins!

I thought about the outlet choice, but the schematic shows the TT30 & The 20A outlet in parallel, so there shouldn't be too much loss there, and the extension cord is 12ga, so could be adding some load, but I wasn't thinking it'd be too much - So yeah, I could re-run the test on the 30A plug w/o the extension.

I'll be running it for a while this weekend, Maybe I'll use up some gas and can put new stuff in.

Thanks to everyone!

CC

[LittleBill]

Edd505 wrote:

LittleBill wrote:
i guess im the only one who thinks its a fuel issue?

how is adjusting rpm/hz going to fix this? resistive heaters don't care about voltage or hz. if the generator is bogging out, sounds like either a restricted air filter or more likely lack of fuel from being clogged

Re jetting is a fuel issue. https://www.youtube.com/watch?v=9FVPeMh3-r0

he doesn't need to rejet at 2200 feet. it would prolly make the issue worse for him, rejetting for higher altitude removes fuel, it doesn't add it

[Edd505]

LittleBill wrote:
i guess im the only one who thinks its a fuel issue?

how is adjusting rpm/hz going to fix this? resistive heaters don't care about voltage or hz. if the generator is bogging out, sounds like either a restricted air filter or more likely lack of fuel from being clogged

Re jetting is a fuel issue. https://www.youtube.com/watch?v=9FVPeMh3-r0

[LittleBill]

i guess im the only one who thinks its a fuel issue?

how is adjusting rpm/hz going to fix this? resistive heaters don't care about voltage or hz. if the generator is bogging out, sounds like either a restricted air filter or more likely lack of fuel from being clogged