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.

[MrWizard]

All modern alternators are revolving field
Your car, your RV, your generator

An alternator has a max load it can produce before being damaged

So does an inverter,

It really doesn't make any difference to the user, where the sense circuit is tied in, on the inverter generator, it man's the same thing, that's it no more load

[MEXICOWANDERER]

Can you even get gasoline free of alcohol on the island?

[BFL13]

Is it the same for a typical inverter like you get for an RV, that has a "low voltage" alarm before the voltage gets lower and then shuts down the 120v output?

That is also to protect the batteries from being sucked down all the way, but is it also because there is not enough DC to make enough AC from?

Is the alarm related to whether it is getting enough DC input? Where that is from batteries with an inverter, or from the revolving field not revolving enough in an inverter-gen?

[MrWizard]

there are three factors here
Engine size/capacity
Alternator size
Inverter electronics

I'm guessing the overload sense/alarm is part of the inverter controls
A monitor circuit for your the input or output of the inverter
The circuit breaker is possibly a magnetic trip, those respond faster to excess current/over the limit, than thermal breakers
And they did not have to cool down before reset
I'm pretty sure the alternator and inverter cost more than the engine
And the circuit protection is geared to them, not to the engine

[BFL13]

Don't know how it senses overload.

It has a circuit breaker for the 120v receptacle and I tested that, and it works. Red light steady, breaker pops. I see on the Kill-A-Watt, that it starts the flashing red warning when the 120v load gets at/just over 1700VA which is the continuous rating.

The manual says its "revolving field is driven at about 4,500 RPM"
Says it can "bog down" if overloaded. Maybe it loses some revs going over 1700VA? Can't hear that, but maybe see it on a rev counter of some kind?

I see the Honda 2200 has a new bigger engine than the previous Honda 2000 has, which must be why it can do more VA? Is that just to keep the revs up when max loaded?

[MEXICOWANDERER]

BFL13,
You are fortunate to live in Refrigeratorland...

Dense high humidity air...

Down here, I have to be careful with cylinder head and alternator stator overheating. The 28" fan (340 watts) feeding the gen room (The monster Horton radiator fan on the Kubota pushes air outside) is not an option.

And I have a rotary fan playing on the Lombardini...

I am wondering how your generator senses "overload" ?

[BFL13]

I like my B&S P2200. Runs great, seems well built, not too loud, and easy to carry. It fits in this Class C. My Honda 3000 would not fit, so "microsizing" 🙂 was compulsory or have no gen at all.

I skipped all the testing "steps" and jumped straight to the actual camping test for seeing if it runs the 75 amper or not. It does.

The flashing red light turns out to be an "early warning" that the gen is approaching being overloaded, but is not yet overloaded. It runs just fine with that red light flashing, and the 75 amps keeps coming to the batteries.

I have not tried higher octane or ethanol free gasoline, now I understand what is going on. As measured both on this gen, the Honda 3000 before that, and also by Mr Wiz, the converter wants about 1700VA to do its 75 amps and the P2200 has 1700w as its continuous rating. It is what it is.

I agree that a Honda 2200 would be a better match with more "overhead" to run the 75 amper. Higher VA continuous and bigger engine. Probably better built too. Costs way more. My choice to pick the B&S P2200 for our situation, and for how often we will ever use it. YMMV.

[JaxDad]

pnichols wrote:

MEXICOWANDERER wrote:
My son-in-law uses a 36 amp Megawatt with a 2-cycle Harbor Freight 700 watt generator. The power supply has a click-click-click switch which allows him to back off demand. Once the batteries have bulk charged he then clicks up two steps to 14.8 volts.

I doubt anything but a very expensive tiny generator could match the gizmo combination for fuel economy.

That is a setup I should almost replicate - a 36 amp Megawatt powered by my little Honda EX650 650 watt four-stroke generator - which is ultra-quiet (54dB) and fuel efficient (1/2 gallon every 5-6 hours). The two should play together great with my 230 AH AGM RV battery bank.

We have a Honda EX650 that we use when flying to remote locations in cold weather. We can’t carry LPG tanks in the aircraft but the little Honda is ok, it also REALLY like 100LL AvGas. Paired with a battery charger it makes frozen batteries happy and easily powers both the oil sump heater and the engine heater at the same time.

This way we can be preheated and ready to go in not much over an hour even in sub-zero temps.

It’s a fantastic little generator.

[pnichols]

MEXICOWANDERER wrote:
My son-in-law uses a 36 amp Megawatt with a 2-cycle Harbor Freight 700 watt generator. The power supply has a click-click-click switch which allows him to back off demand. Once the batteries have bulk charged he then clicks up two steps to 14.8 volts.

I doubt anything but a very expensive tiny generator could match the gizmo combination for fuel economy.

That is a setup I should almost replicate - a 36 amp Megawatt powered by my little Honda EX650 650 watt four-stroke generator - which is ultra-quiet (54dB) and fuel efficient (1/2 gallon every 5-6 hours). The two should play together great with my 230 AH AGM RV battery bank.

[MEXICOWANDERER]

My son-in-law uses a 36 amp Megawatt with a 2-cycle Harbor Freight 700 watt generator. The power supply has a click-click-click switch which allows him to back off demand. Once the batteries have bulk charged he then clicks up two steps to 14.8 volts.

I doubt anything but a very expensive tiny generator could match the gizmo combination for fuel economy.

[Gdetrailer]

BFL13 wrote:

#1 Misses the whole point IMO. It is this variety that makes it so difficult to match the converter "size" to the generator "size" needed to run it for battery charging while camping.

#2 My test approach is to do it in real life. As seen, you get different answers from using the converter as "supply" (less VA needed) from "battery charging" (more VA needed) Also true that it varies by battery type.

#3 If you use a scientific fixed load to see what the gen can do, you miss the problem of just how much load your chosen converter will be when faced with your particular battery bank (type of battery, condition, wiring set-up, etc) at different SOCs.

#4 Some converter makers also seem to rate their converters using an artificial fixed load, and publish misleading "specs" as a result, which understate the VA needed on a real battery bank.

#5 In my case, I started with the actual VA this 75 amp converter required from my previous Honda 3000 on my actual battery bank (just under 1700) and matched that with the generator spec of 1700w continuous for my new generator.

#6 I also thought being a "2200" it would have some margin above 1700. My Honda 3000 could do more than its rating without overloading.


#7 Of course I don't like the word "flawed" there, but take comfort in seeing how closely Mr Wiz's results match mine with totally different set-ups except having the same model of converter. IMO this shows the measurements are valid.

#8 You want the test to be what will happen when you are actually out there off grid with your batteries at 50% and you will be using your converter from your generator. Can it do it or not? Know before you go!

#9 There still doesn't seem to be a reliable way to shop for a gen and converter to know exactly how they will match to get the most DC charging amps from the published gen ratings and converter ratings. It is expensive to get it wrong if they don't take "returns" on those.

You have to be lucky enough to be on this forum before you go shopping to get at least some notion about that. 🙂

Cleaned up and added item numbers to make my comments vs your comments easy to follow..

#1 Splitting hairs by trying to micro size your gen when camping. It is well known that 1Kw-2kw gens are on pretty shaky ground concerning trying to recharge your RV batteries let alone try to do anything else on top of that. There is very little headroom to work with on smaller gens and you have nothing to gain or save by micro sizing your gen.

#2 Your "test" does not fully reflect "real life" since you have too many "variables" which are skewing your initial base test to see if it works with that gen. Remove the variables, THEN ONE BY ONE ADD THE VARIABLES BACK IN UNTIL IT FAILS. This IS a valid "scientific approach".

#3 Starting with a "KNOWN" fixed load (non variable) you find out IF your generator CAN handle the converter load of say 75A on the 12V side. If the generator passes this test, THEN you ADD say the battery back in to the test and ADD say a 75A non variable load to the battery AND THE CONVERTER. By doing this you are methodically going one by one through all of your "scenarios".

#4 You don't really "know" what the manufactures have used to "rate" their specifications. You ARE "assuming" that they are using a "static" load.. What I can tell you is there IS some "slop" allowed in their "specifications" due to tolerance stacking in the components.

Tolerance stacking means that the sum of all the tolerances of all the components within a device must not exceed the manufacturers final specifications.

In a nutshell, due to component tolerances there is an "acceptable range" that the manufacturer will allow to go out the door. So, when they say a converter can do 75A at say 14V that supply MUST be able to at least supply that current at that voltage.. The input voltage and current will also have a tolerance range.

#5 As I mentioned before, comparing a "non inverter gen that IS larger to a SMALLER Inverter gen is "Apples and oranges" type of comparison. In reality, you NEED to take say a 2Kw NON INVERTER gen and a 2Kw Honda INVERTER gen and see if those pass your test..

I PERSONALLY THINK THEY WILL WORK BETTER THAN THE B&S INVERTER GEN.

#6 Not sure what gives you this "idea" that a CHEAP UNDERSIZED B&S inverter gen will work as good as a 3Kw name brand gen. That B&S gen IS a Chinese gen and I highly doubt that it is capable of handling the reactive load you giving it.. Better gens most likely will have a better chance of dealing with a reactive load.

#7 "Flawed" definition..

HERE

"Flaw..

1. An imperfection, often concealed, that impairs soundness: a flaw in the crystal that caused it to shatter. See Synonyms at blemish.
2. A defect or shortcoming in something intangible: The two leaders share the flaw of arrogance.
tr.v. flawed, flaw·ing, flaws
To cause a flaw in; make defective: an argument that was flawed by specious reasoning.

Flawed..

characterized by a defect or imperfection: The scheme is fundamentally flawed.. "

Seems to fit when you have too many "variables" in your tests..

#8 Which IS why you start with a KNOWN "load" to start with then add in your variables. This way you KNOW where the problem lies. Right now, you simply know that it won't work the way you want or need it to.

Also known as "Process of elimination", one of the very FIRST basic lessens that I learned 30+ years ago in Tech school for troubleshooting electronics..

#9 Working with AC voltages it is much more complex than working with DC voltages. It is a very complex relationship due to something called IMPEDANCE (Impedance is a combination of resistance, inductance and capacitance which a switching power supply does present to the AC load..

Impedance plays havoc with your tests and is difficult to quantify.. You would have to really get done to the nuts and bolts of the circuit at hand to determine what is happening, pretty much an Electrical engineering job.

Honestly, way over thinking this, much simpler sometimes to simply move up a notch in your generator size or buying a BETTER "BRAND" to get the results you are requiring..

[BFL13]

Gdetrailer wrote: (skipped some of his post--see original for full post)


"Personally, I suspect that your "test results" are highly flawed due to too many unaccountable "variables". You are using a lot of highly variable loads which potentially can skew your results.

Batteries present highly variability as does your inverter load on the battery."

Misses the whole point IMO. It is this variety that makes it so difficult to match the converter "size" to the generator "size" needed to run it for battery charging while camping.

My test approach is to do it in real life. As seen, you get different answers from using the converter as "supply" (less VA needed) from "battery charging" (more VA needed) Also true that it varies by battery type.

If you use a scientific fixed load to see what the gen can do, you miss the problem of just how much load your chosen converter will be when faced with your particular battery bank (type of battery, condition, wiring set-up, etc) at different SOCs.

Some converter makers also seem to rate their converters using an artificial fixed load, and publish misleading "specs" as a result, which understate the VA needed on a real battery bank.

In my case, I started with the actual VA this 75 amp converter required from my previous Honda 3000 on my actual battery bank (just under 1700) and matched that with the generator spec of 1700w continuous for my new generator.

I also thought being a "2200" it would have some margin above 1700. My Honda 3000 could do more than its rating without overloading.

It turned out as seen in this thread. Now that I know where it all stands in real life from using the Kill-A-Watt and Trimetric, I can decide what to do when that red light starts flashing, based on those real numbers.

Of course I don't like the word "flawed" there, but take comfort in seeing how closely Mr Wiz's results match mine with totally different set-ups except having the same model of converter. IMO this shows the measurements are valid.

You want the test to be what will happen when you are actually out there off grid with your batteries at 50% and you will be using your converter from your generator. Can it do it or not? Know before you go!

There still doesn't seem to be a reliable way to shop for a gen and converter to know exactly how they will match to get the most DC charging amps from the published gen ratings and converter ratings. It is expensive to get it wrong if they don't take "returns" on those.

You have to be lucky enough to be on this forum before you go shopping to get at least some notion about that. 🙂

[MEXICOWANDERER]

"Ya think if we mandated it then really hyped up the benefits, threw in some buzzwords, 'planet' 'global warming' 'smog' any of 'em will get wise to it? By the way what's ADM trading at today?"

[Gdetrailer]

philh wrote:
Ethanol free gasoline
https://www.pure-gas.org/

:R

Yeah, that website gets posted often around on this forum.

It IS often incorrect and lists several gas stations near me offering Ethanol free gas which is not really true unless you are going to run your vehicles on the local dirt race track..

Those stations only "offer" Ethanol free racing fuel IF you show your PIT PASS for that night..

Next myth up is "AV" fuel, yeah there is a couple of local airports that do have Ethanol free 100LL. And NO, they DO NOT SELL TO THE GENERAL PUBLIC (AND YES I DID CALL THEM AND SPECIFICALLY ASK).

To get "AV" fuel you MUST present a VALID TAIL NUMBER..

In PA, Ethanol free RACING fuel and Ethanol free AV fuel ARE NOT TAXED THE SAME AS FUELS SOLD FOR ROAD USE, those applications do not get road taxes charged and using those fuels to drive vehicles on public roads is TAX EVASION..

Besides, most folks do not realize that gasoline has been laced with Ethanol since the 1970s (remember "Gasohol"? Yeah it didn't sell then but the corn lobby figured out that they COULD force folks to use it by lobbying regulations into existence that force folks to use it)..

So, in reality Ethanol laced motor fuel has been secretly in use for over 40 yrs..

Not to mention as early as 1905 straight Ethanol was being experimented with for use in ICE engines.. Interestingly enough they figured out back then that it cost more to produce Ethanol than using 100% out of the ground derived gasoline..

[philh]

Ethanol free gasoline
https://www.pure-gas.org/