Would Higher Octane Run the Gen Better? UPDATE

[BFL13]

UPDATE 21 Nov page 5

Ongoing saga with my 1700w (continuous) gen trying to run my 75 amp charger at 75 amps. Briggs and Stratton P2200 gen.

Previously posted that it would not (flashing overload red light), then discovered I still had it choked. Next test was to run it with the batteries full, but with an inverter draw of 127 amps, then turn on the charger, but now with the gen choke in the right place. Amps now -52 so 127 minus 52 = 75 amps from the converter/charger. No flashing overload light on gen. So I reported success.

Just been camping off grid, did a recharge with the gen and the 75 amper. No red light at first. 75 amps to battery bank. Then after a few minutes the red light started flashing but gen kept running.(It can shut off with overload.) Switched to the 55 amp charger and no red light.

We know that running a charger as a power supply is easier than doing an actual battery recharge due to the higher battery resistance. Sometimes it can do its full amps as a power supply, but might not be able to do its full amps on the battery. BUT--I thought that if it did its 75 amps as supply that was the same effort as doing 75 amps on a battery.

Here, 75 amps on battery seems to take more effort from the charger than doing supply, so needs more from the generator? 75 is not the same 75?

Also there is some relationship between the generator engine running and the power output, as seen when it was choked and did less 120v power. I am wondering if the gen would run the 75 amper without the flashing overload light if only the engine ran a little "better" (not sure what I mean by that in what the engine would have to do) More revs?

The manual mentions engine getting bogged down with too much load-I did not hear it running slower.

So finally after all that background--would the engine do "better" if it ran on higher octane gasoline? It has 87 now (regular). And if it did, would that make the difference to output power I need where I am just on the edge for running that 75 amper?

Engine is 6.77 cu-in(111 cc), 4500 revs single-cylinder, revolving field, wants 87 octane minimum below 2500 ft altitude.

I will not have an opportunity to try that for a while, so I am asking here to learn if it is worth trying at all. Thanks.

[BFL13]

Kill-A-Watt when charger doing power supply was:

119v, 13.67a, 1150w, 1626VA, 0.70 PF. I don't have the battery voltage but let's say it was 12v under that inverter load and with the charger doing 75 amps.

Output watts DC 75 x 12 = 900w so efficiency is 900/1150 = 78%

Now estimating when battery charging, 75 amps at 13.5v say.

Output watts DC 75 x 13.5 = 1013w. Using 78%, then input watts would be 1298 and with PF at 0.7, VA would need to be 1854. Oops!

I will try to get real Kill-A-Watt numbers when battery charging if I can get enough time at 75 amps before the red light starts flashing, next time I get at it. Also use fresh gas.

[BFL13]

MrWizard wrote:
IIRC you have done power factor and load tests

But I don't remember what the VA and PF were

I think You are hitting the limits

Cooler temps mean higher charging voltages for lead batteries (AGM is lead)

When you did the power supply test, supply voyage was lower, the battery was under load, the combine converter & battery voltage level was probably barely above 13v maybe less
13*75 is less than 14.× * 75
Which means a different VA loading on the generator

92 Oct non ethanol may help, warmer weather may help
A bigger generator or smaller charger WILL help

So you use the battery voltage for "output watts" and not the voltage set on the charger. That would make the required input VA different for the same output amps.

I need to do a Kill-A-Watt while battery charging and compare results.

I have a 75 and a 55 to choose from. Probably should have the 65 amper and no worries. The 55 is more gen time than the 75 but it gets it done (eventually).

[BFL13]

pnichols wrote:
BF,

What fuel will help your generator you probably can't get to run in it - gas with no alcohol in it. Is this possible up there where you're located?

I can get lower percentage perhaps zero, of ethanol (gasohol) in high premium gas at some stations AFAIK, but I don't know about alcohol. They sell "marked gas" (colour in it- not for all comers) and gas for boat engines with no ethanol.

The grateful gubmint says they have to have an average of 5% ethanol, so they make 87 10%, 89 5%, and 91 0%, but lately that might have changed so now some 91 might have some ethanol, but there is a 93 or 94 octane some places that is still zero % AFAIK.

[pnichols]

BF,

What fuel will help your generator you probably can't get to run in it - gas with no alcohol in it. Is this possible up there where you're located?

[MEXICOWANDERER]

Alcohol

LOOZE THE BOOZE and see what happens. Even if you have to run premium. It's a test

If it's a flathead engine, remove ten bolts and get the head milled .060" at an automotive machine shop. Cannot do with overhead valve engine.

I had a rotary snow blower at 7,800 ft altitude. 8 horsepower. Had the head milled and the machine threw snow six feet further. This isn't black magic.

[BFL13]

"If the output voltage is higher, then the power is of course greater...and conversely if the system voltage is lower, the output power is lower, assuming the current remains constant."

I am not clear on the "system voltage". The charger's voltage is set at 14.6v and stays there solid the whole time. 75 is constant the whole time during these two situations.

In "power supply", the battery bank is being drawn down by the inverter pulling 127 amps (MW) and so battery voltage is low. The charger then supplies 75 amps and now the battery draw is 52 amps but its voltage is still low, just not as low.

In "battery charging" the battery voltage is in the 13s at first then climbs. So the charger is facing higher resistance than when doing "supply", but it is still doing its 75 amps.

I have seen it before where a converter will do full amps doing "supply" but not when battery charging. Eg a 7355 in the 5er did 56 amps but only 35 amps battery charging--and on the same wires to the battery.

So I think the charger doing 75 on battery charging could need more input than when doing 75 amps as supply. No?

Brings up an old question I never got clear on--is charger "output watts" using the charger's voltage setting, or is it using the battery voltage in the watts?

[DrewE]

If the charger's output current and voltage are the same when it's charging as when it's doing power supply work, then it's consuming the same amount of input power; it couldn't even tell the difference between the two.

If the output voltage is higher, then the power is of course greater...and conversely if the system voltage is lower, the output power is lower, assuming the current remains constant. For a typical current limiting power supply (as opposed to a constant voltage-constant current supply which regulates the maximum current), the transition into current limiting isn't super precise and the voltage may sag as the current limit is approached.

In the generator, the engine speed and throttle are adjusted by the generator's brain based on the load, which varies the voltage and current output of the internal alternator. (I would assume it's also adjusting the excitation voltage at the same time, though I would be clueless as to the exact relations between RPM and excitation voltage it maintains as power consumption varies). Since the output you see is synthesized and not directly from this alternator, the fluctuating voltage is of little import unless it drops too low due to overloading or a sudden large increase in power consumption that the engine isn't quick enough to respond to.

I rather doubt you'd see significant gains in power from "better" gas or synthetic oil. If the carburetor or air filter needs cleaning or the spark plug is worn or the valves need adjusting, fixing those could very well improve the power output. My guess (and it's only a guess, not even a hunch) is that you're simply consuming more power now, not that the generator has degraded performance compared to previously.

[BFL13]

Seems to be lot to this whole thing. I am most interested in the relationship between engine and inverter output for the ratings.

Manual says:

This generator is an engine-driven, revolving field....The revolving field is driven at about 4,500 rpm by a single-cylinder engine. (straight gas--not oil and gas mix)

It does slow down when not running a big load and it speeds up to run more of a 120v load. Something must be going on between revs and output?

So I am on the borderline between can and can't run this 75 amper which should run at the rated 1700VA. According to my Kill-A-Watt charger VA is about 1650)

So why can't it? Is it not doing that 4500 revs? Can I make it do those needed revs with better gasoline, synthetic oil, or pray to a different god? Or is it doing the revs but there is something not quite right going from engine to inverter output at the inverter's end of things?

I don't know the inner workings to even know where to start. I also have that measurement that it will run the charger at 75 amps if the charger is doing power supply, but not if it is doing battery charging. My 1650VA was doing power supply. I suppose I need to see the VA when battery charging to get that number. Both are at 75 amps, but the charger is current limited at 75 so it could need more input to do 75 when battery charging, don't know.

So that is something else to check. Drat. This was supposed to be easy. 🙂

[opnspaces]

Here's what I remember from my technician training at Toyota regional headquarters many many years ago.

When the fuel air mixture ignites in the cylinder it is a controlled burn and not an explosion which would be an uncontrolled burn. The engineers through testing know just how long the flame front takes to cross the combustion chamber and burn the air fuel mixture.

If you take an engine designed for regular 87 octane fuel and increase the compression through say head work or excessive carbon build up, the flame front speed increases and you can get detonation (pinging/explosion)

Higher octane fuel burns slower than lower octane fuel. By adding a higher octane fuel you slow down the flame front and stop the pinging/damage.

So along that line. If you take a good condition engine that is engineered for 87 octane fuel and just introduce premium fuel you slow the flame front and decrease power. In reality you will probably never know the power is reduced without laboratory equipment, but you have still effectively lowered the power output of the engine.

on the flip side, higher performance engines typically have higher compression ratios and need the higher octane fuel to slow the flame front and prevent detonation.

[MrWizard]

IIRC you have done power factor and load tests

But I don't remember what the VA and PF were

I think You are hitting the limits

Cooler temps mean higher charging voltages for lead batteries (AGM is lead)

When you did the power supply test, supply voyage was lower, the battery was under load, the combine converter & battery voltage level was probably barely above 13v maybe less
13*75 is less than 14.× * 75
Which means a different VA loading on the generator

92 Oct non ethanol may help, warmer weather may help
A bigger generator or smaller charger WILL help

[BFL13]

3 tons wrote:
Though it may seem counterintuitive, Premium gasoline has less energy content (less volitile) than regular gasoline, but higher compression engines are more efficient, thus, more power.

3 tons

I am learning lots here, but not too clear if it will do me any good! I see the Honda 2200 has their new 121 cc engine and is rated at 1800w continuous while my 2200 gen has a 111 CC engine and is good to 1700w.

I don't know what that means in how the engine power relates to 120v output power limits, or what the revs have to do with it, etc.

I will do the next recharge with fresh 87 and see how that goes.

[3_tons]

Though it may seem counterintuitive, Premium gasoline has less energy content (less volitile) than regular gasoline, but higher compression engines are more efficient, thus, more power.

3 tons

[BFL13]

Ok at the gas pumps locally, there is no individual ethanol percentage, but just a statement for all that "may contain up to 10% ethanol" You have to check their websites apparently.

I can see that the oil might matter if it affects revs at all.

I believe the engine does matter because it has that revolving field thing for the electrical output.

If it slows down like when I had it choked by mistake, it ran, but overloaded easily, and when I put the choke over to where it belongs, the red flashing light stopped and you could hear that it was revving higher.

The manual says it can "bog down" if overloaded. I think what I want is to keep the revs right up at that max rated load 1700VA. Not too clear about that and whether "clean" fresh gas (even fresh 87) would do it.

I have measured the load of the 75 amper with the Kill-A-Watt and it is pulling just under 1700VA when doing 75 amps and set to about 14.6v, so it ought not to overload this gen. It did not overload it when the 75 amper was doing power supply. It does when on battery charging duty. I think it is almost ok and perhaps it just needs better gasoline or perhaps the oil as was suggested. Just have to keep trying things.

Looks like I have to try it with clean, fresh gas next time. I don't want to change the oil to synthetic also, because then I wouldn't know which was the cure if it works. One thing at a time.

I did use the 55 amper instead. Then I started the engine for some alternator. Amps jumped to 70 so they do add their amps, but with the alternator voltage lower, you don't get all those amps, just some. No solar in the woods to add any amps. So I would like to get that 75 to work off the gen. We'll see.

[wa8yxm]

75 amps (Charger) draws over 1,000 watts if batteries hungry.. at least in many cases 75 times 14.6 times inverse of conversion loss (WHich can be 20 percent or more when combined with pwoer factor) and the 1000 watt generator is .. overloaded. Espicaly since that's 1,000 PEAK. Oh I see yours is a 2000 watt (2200 peak) still if there is something else there. OVERLOAD (Water heater???)

NO premium or Marine grade (no Alcohol) will not improve generator performance the overload light refers to the generator NOT the engine.

[pianotuna]

Hi BFL13,

For the last two fills of the season I switch to Premium and add seafoam. The rest of the time it is regular gas.