How efficient is your generator?

[shazam]

Testing results for military MEP803A 10kW 1800 rpm pure sine wave diesel generator...
Not my figures...testing done by a member of the Steel Soldiers Generator forum.

.45 gph at 2000 watts
.50 gph at 3500 watts
.60 gph at 4500 watts
.90 gph at 9000 watts

Jim

 

[dougbert]

yes, I also saw that. Some good info at least for a form of comparison
locally there is a one of those MEP generators for sale for just under $3,000

 

[shazam]

If it's a decent 803 that's a great price. Guessing it's not...

We've got ours set up with an after-market two-wire start kit, and MEP (main electrical panel) internal gen. lock-out currently. Power out?... Down the basement, throw the switch, and then the breaker. 7 gallon tank lasts awhile ?

When the SA 15K install is finished, we'll move the two-wire start to it, and use it to charge the batts when the sun is on strike.

It's an adventure!
Jim

 

[dougbert]

yes, I also saw that. Some good info at least for a form of comparison
locally there is a one of those MEP generators for sale for just under $3,000

gone already

here is a

Generator Military 5KW MEP 002A Skid Mounted Diesel $2200​

Generator Military 5KW MEP 002A Skid Mounted Diesel $2200

$2,200.00 Generator Military 5KW MEP 002A Skid Mounted Diesel $2200 for sale in Tooele, UT on KSL Classifieds. View a wide selection of Generators and other great items on KSL Classifieds.

classifieds.ksl.com

got a pic as it will be gone shortly and link will be stale

Utah

 

[shazam]

Those 002/3 were older military units of 5 and 10 kW. As I recall those models were air-cooled. Here's the 803...it's a beast!

 

[dougbert]

Those 002/3 were older military units of 5 and 10 kW. As I recall those models were air-cooled. Here's the 803...it's a beast!View attachment 190305

Out standing (sitting) in its field - sound reduction by distance and grass

 

[shazam]

Out standing (sitting) in its field - sound reduction by distance and grass

Actually, that pic was taken from my bedroom window. ? With the ICF walls, it'a just a low rumble.

It's an adventure!
Jim

 

[OffGridInTheCity]

Finally got into a position to do a gasoline test on my duel-fuel Champion 8000w Model 100297 - https://www.championpowerequipment.com/product/100297-8000w-electric-start-dual-fuel-generator/


Set my Chargeverter 5000 V1 to 100a and did 10kw at 100a charging at ~53v battery over ~1.7hrs. Overall, the generator provided 10.0kwh of AC into the Chargerverter (per IotaWatt) for 1.5gal of gas. 10,000w / 1.5gal = 6,667w per gallon of AC provided.

The Chargeverter is ~90% efficient which means....
* I got 9kwh into the batteries / 1.5gal = ~6000w of DC charge per gallon of premium gasoline.
* 100a * ~53v = ~5300w of charging means the generator was providing ~5900w continuously. This is consistent with live IotaWatt readings.
* The Generator specs say 8000w Gas and 7250w Propane 'running power' so it seems well matched for a 100a Chargeverter - and gas is now confirmed for me.

I'm pleased except for the NOISE. The Champion has a 74dBA rating. Even in an enclosed shed with 6" insulation, siding, double dry-wall inside, baffle box on the exhaust out of the shed the dB is still ~63 at 5 feet away from the shed with deep throbbing. It's louder than I would ever have imagined before starting the shed project. As I understand 'dB' concepts it means I've cut noise by ~50% - but wow, it's still loud enough to bother the neighbors.

As a comparison, my Honda eu3000is with 57dBA specs is ~50 db at 5 feet away from the shed and pretty darn quiet - more what I was hoping for with the Champion. During the zombie apocalypse I'll be running the Honda only to reduce chances of them hearing me.

Haven't tried a propane test yet but will get to it eventually....

 

[Kremer]

Here is some math on Honda inverter generators I did some time ago based on Honda's run time claims at 1/4 and full load:

The Honda EU7000 burns 5.1 gallons of gasoline in 6.5 hours at 5500 W to make 35.75 kWh at 7.00 kWh/gal (fuel injected!)
The Honda EU6500 burns 4.5 gallons of gasoline in 4.7 hours at 5500 W to make 25.85 kWh at 5.74 kWh/gal
The Honda EU3200 burns 1.2 gallons of gasoline in 3.3 hours at 2600 W to make 8.58 kWh at 7.15 kWh/gal (fuel injected!)
The Honda EU3000 burns 3.4 gallons of gasoline in 7.2 hours at 2800 W to make 20.16 kWh at 5.93 kWh/gal
The Honda EU3000 Handi burns 1.56 gallons of gasoline in 3.6 hours at 2600 W to make 9.36 kWh at 6.00 kWh/gal
The Honda EU2000 burns 1.08 gallons of gasoline in 4 hours at 1600 W to make 6.4 kWh at 5.93 kWh/gal

The EU6500i 5.5 kW at 1/4 load burns 4.5 gallons for 14 hours:
5.5 kW * 1/4 * 14 hours * 1/4.5 gallons = 4.28 kWhrs per gallon of fuel (at 1,375 watts). (fuel injected!)
The EU3200i 2.6 kW at 1/4 load burns 1.2 gallons for 8.6 hours:
2.6 kW * 1/4 * 8.6 hours * 1/1.2 gallons = 5.59 kWhrs per gallon of fuel (at 650 watts). (fuel injected!)
The EU3000i 2.8 kW at 1/4 load burns 2.4 gallons for 20 hours:
2.8 kW * 1/4 * 20 hours * 1/3.4 gallons = 4.12 kWhrs per gallon of fuel (at 700 watts).
The EU3000 handi 2.6 kW at 1/4 load burns 1.56 gallons for 7.7 hours:
2.6 kW * 1/4 * 7.7 hours * 1/1.56 gallons = 3.21 kWhrs per gallon of fuel (at 650 watts).
The EU2000i 1.6 kW at 1/4 load burns 1.1 gallons for 15 hours:
1.6 kW * 1/4 * 15 hours * 1/1.1 gallons = 5.45 kWhrs per gallon of fuel (at 400 watts).

 

[wpns]

Multiply by the price of fuel and that's pretty pricey!

 

[Checkthisout]

Multiply by the price of fuel and that's pretty pricey!

Yes.

However, it's usually needed during winter.

One can be clever and recover the waste heat from the genny and heat the living space and/or water.

 

[Symbioquine]

Here is some math on Honda inverter generators I did some time ago based on Honda's run time claims at 1/4 and full load:

Is that all extrapolated from their marketing numbers or have you measured for yourself?

Set my Chargeverter 5000 V1 to 100a and did 10kw at 100a charging at ~53v battery over ~1.7hrs. Overall, the generator provided 10.0kwh of AC into the Chargerverter (per IotaWatt) for 1.5gal of gas. 10,000w / 1.5gal = 6,667w per gallon of AC provided.

The Chargeverter is ~90% efficient which means....
* I got 9kwh into the batteries / 1.5gal = ~6000w of DC charge per gallon of premium gasoline.

6.667 (kWh generated) / 33.41 (kWh total energy) = 19.95% efficiency
6 (kWh generated) / 33.41 (kWh total energy) = 17.96% efficiency

If we assume ~$6/gal for fancy ethanol free gas in the US, that's about $1/kWh.

Multiply by the price of fuel and that's pretty pricey!

Arguably, one can figure out the yearly "effective cost per kWh" (for off-grid systems) by dividing total system kWh produced (from both solar and generator) by the cost of the fuel.

However, I struggle with this a bit because one should also consider the amortized cost of all the equipment and the maintenance - which gets tricky to calculate if you don't know how far into the future the equipment will last. A more thorough accounting presumably would need to include replacement cost (including labor and downtime) for the equipment.

On the whole I think that's a serious rabbit hole and deserves its own thread. Lets just stick with the actual generator efficiency itself in this thread.

 

[wpns]

However, I struggle with this a bit because one should also consider the amortized cost of all the equipment and the maintenance - which gets tricky to calculate if you don't know how far into the future the equipment will last.

Exactly. And don’t forget the time value of money!

 

[OffGridInTheCity]

Arguably, one can figure out the yearly "effective cost per kWh" (for off-grid systems) by dividing total system kWh produced (from both solar and generator) by the cost of the fuel.

I've gradually come to learn that fossil fuel generator power is not 'the best'. The mechanical/physical *effort/horsepower* required to generate electricity by engine or water or wind is huge. PV is just sooo much smoother, quieter, no mechanical maintenance etc etc. The horsepower/noise/fuel for 6000w of charging power just seem like a loosing effort compared to panels.

My biggest disappointment is heating the house. I've tracked my whole house, highly efficient, 4-ton heat-pump over a few years now with some years being 100% electric and some being natural gas assist. I live in a mild Zone 4 climate and thought, 100% electric + PV + generator (in winter) = no problem.

But I've come to see generators as not practical or best use of fuel for heat - even with a heat pump + mild climate (avg 35F low).

For example, to do 100% electric heat for the 4 months of winter in a 2600sq ft house I need ~5600kwh of power. My 14.5kw PV (51 panels) get's me ~2400kwh of that leaving a 3200kwh gap. Using 200 Therms of natural gas (~200gal of propane) the heat-pump 4 month power use drops to ~2400kwh.

3200kwh / 200gal means I'd need to generate 16kwh / gal of propane to go 100% electric route with the same efficiency as burning the fuel for heat. Turning it around, I'd need 533gal of propane instead of 200gal for the same heat + maint to mechanically generate 3200kwh It's just more efficient to use fuel for heat than to generate electricity for heat.

Deeply disappointing compared to my original rose colored glasses.

However, if I could just build a container with 40 or 60 or 80 used EV batteries and store 4000kwh of power during summer to be used during winter - it would only be 1 cycle per year so used EV batteries should work great!

 

[wpns]

I've gradually come to learn that fossil fuel generator power is not 'the best'. The mechanical/physical *effort/horsepower* required to generate electricity by engine or water or wind is huge. PV is just sooo much smoother, quieter, no mechanical maintenance etc etc. The horsepower/noise/fuel for 6000w of charging power just seem like a loosing effort compared to panels.

My biggest disappointment is heating the house. I've tracked my whole house, highly efficient, 4-ton heat-pump over a few years now with some years being 100% electric and some being natural gas assist. I live in a mild Zone 4 climate and thought, 100% electric + PV + generator (in winter) = no problem.

But I've come to see generators as not practical or best use of fuel for heat - even with a heat pump + mild climate (avg 35F low).

For example, to do 100% electric heat for the 4 months of winter in a 2600sq ft house I need ~5600kwh of power. My 14.5kw PV (51 panels) get's me ~2400kwh of that leaving a 3200kwh for the gap. Using natural 200 Therms of natural gas (~200gal of propane) the heat-pump 4 month power use drops to ~2400kwh.

3200kwh / 200gal means I'd need to generate 16kwh / gal of propane to go 100% electric route. Turning it around, I'd need 533gal of propane instead of 200gal for the same heat + maint to mechanically generate 3200kwh It's just more efficient to use fuel for heat than to generate electricity for heat.

Deeply disappointing compared to my original rose colored glasses.

However, if I could just build a container with 40 or 60 or 80 used EV batteries and store 4000kwh of power during summer to be used during winter - it would only be 1 cycle per year so used EV batteries should work great!

Yeah, heat pumps are a big win with reasonable grid electricity prices but (unless you can capture waste heat from your generator) generators are way too inefficient to generate electricity with.

 

[Brucey]

I've gradually come to learn that fossil fuel generator power is not 'the best'. The mechanical/physical *effort/horsepower* required to generate electricity by engine or water or wind is huge. PV is just sooo much smoother, quieter, no mechanical maintenance etc etc. The horsepower/noise/fuel for 6000w of charging power just seem like a loosing effort compared to panels.

My biggest disappointment is heating the house. I've tracked my whole house, highly efficient, 4-ton heat-pump over a few years now with some years being 100% electric and some being natural gas assist. I live in a mild Zone 4 climate and thought, 100% electric + PV + generator (in winter) = no problem.

But I've come to see generators as not practical or best use of fuel for heat - even with a heat pump + mild climate (avg 35F low).

For example, to do 100% electric heat for the 4 months of winter in a 2600sq ft house I need ~5600kwh of power. My 14.5kw PV (51 panels) get's me ~2400kwh of that leaving a 3200kwh gap. Using 200 Therms of natural gas (~200gal of propane) the heat-pump 4 month power use drops to ~2400kwh.

3200kwh / 200gal means I'd need to generate 16kwh / gal of propane to go 100% electric route with the same efficiency as burning the fuel for heat. Turning it around, I'd need 533gal of propane instead of 200gal for the same heat + maint to mechanically generate 3200kwh It's just more efficient to use fuel for heat than to generate electricity for heat.

Deeply disappointing compared to my original rose colored glasses.

However, if I could just build a container with 40 or 60 or 80 used EV batteries and store 4000kwh of power during summer to be used during winter - it would only be 1 cycle per year so used EV batteries should work great!

Double your panels and should nearly cover winter usage.

 

[OffGridInTheCity]

Double your panels and should nearly cover winter usage.

Agreed but.... I'm at 51 panels (14.5kw) but don't have room for another set

 

[Brucey]

Ground mount time! Plus saves the work of mowing the grass.

 

[OffGridInTheCity]

Just wrapped up a 50minute propane test on the duel-fuel Champion 8000w Model 100297 with Chargeverter set to 100a -
https://www.championpowerequipment.com/product/100297-8000w-electric-start-dual-fuel-generator/

Generator -> Chargeverter performed smoothly (no issue with generator) as expected.

Fuel: 30lb propane tank went from 41lbs -> 34lbs = 7lb drop which is ~1.6gal using 4.3lbs/gal because it's 50F today.

Generated 5.24kwh on 1.6gal = 3.2kwh/gal of propane which is way lower than expected. **Used cheap bathroom scale to weigh tank**

Will do another run in a few days (give neighbors a break) and re-weigh the tank and do a follow up post on propane consumed.

Here's a bunch of detail in the form of a 'snapshot' of my dashboard figures at one point during the run....

 

[Kremer]

Is that all extrapolated from their marketing numbers or have you measured for yourself?

Math on their published load and runtime claims.

 

[wattmatters]

With propane I just assume 50.3 MJ/kg = 13.97 kWh per kg or 6.34 kWh per lb.
7 lbs = 44.4 kWh

5.24 out / 43.8 in = 11.8%

**Used cheap bathroom scale to weigh tank**

Both precision and accuracy of such scales is typically poor and especially at lower weights.

I once had two gym weight plates (~20kg and ~15 kg) weighed to the nearest 5g at two verified transit centre weight scales. I used to use them for calibrating strain gauges in bicycle power meters but also once used them to calibrate a bathroom scale. If you are friendly with a local service provided with a verified scale you could do a before and after with their scale.

 

[OffGridInTheCity]

eu3000is -> Chargeverter propane test. Gen is 23yrs old.


Propane Used: 31.8lb - 29.2lb = 2.6lbs / 4.11lbs per gallon = 0.633gallons.

AC Power Generated: Test ran for 99minutes starting at 2530w rising to 2560w of AC for 4.14kWh of AC power produced (per Iotawatt monitor).

Results Per Gallon of Propane....
Generator AC Produced: 4.14kWh per 0.633gal -> gallons is 4.14kWh * 1.58 = 6.540kwh.
Battery Charge: 6.540kwh * 88.5% = 5.755kWh.

This is a bit higher than I was expecting but possible. Propane weights measured by this bathroom scale - https://www.amazon.com/gp/product/B0C5DCTH9M/ref=ppx_yo_dt_b_search_asin_title


------------- Supporting info ---------------------
IotaWatt graph of the run showing the generator AC power produced




------------------------------------------------
Chargeverter operating at 120v@43.1a -> 52v battery providing 2241w of charging / 2533w AC = ~88.5% efficiency.
This Chargeverter pic taken at end of test shows 43.1a @ 52.3v battery and 4.2kWh of 'energy' - corresponds with incoming AC 'energy'.
Note: Interesting that Chargeverter is not showing battery charge energy... Hmmm.... one would assume this was charge so it seems to be overstating what one would assume


Start of test - Iotawatt is showing an initial 2533w incoming AC from the generator at a 97% power factor.

At end of the test, 2570 watts of generator AC at 98% PF.

 

[Symbioquine]

Results Per Gallon of Propane....
Generator AC Produced:[/B] 4.14kWh per 0.633gal -> gallons is 4.14kWh * 1.58 = 6.540kwh.
Battery Charge: 6.540kwh * 88.5% = 5.755kWh.

6.540 (kWh generated) / 27.988 (kWh total energy) = 23.4% efficiency

5.755 (kWh generated) / 27.988 (kWh total energy) = 20.6% efficiency

Those are awesome numbers if they can be believed (rivaling the gas/diesel numbers we've seen)... Maybe you can double-check the 5.755 number by comparing the before/after charge state of your batteries?

 

[OffGridInTheCity]

Those are awesome numbers if they can be believed (rivaling the gas/diesel numbers we've seen)... Maybe you can double-check the 5.755 number by comparing the before/after charge state of your batteries?

I know what you mean but unfortunately there was significant PV production and varying loads during the test which makes battery voltage or SoC in my setup unreliable for this. During the test I did some 'instantaneous' math between load (as reported by Batrium shunt and IotaWatt) and PV numbers (as reported by Midnite Classic) to confirm the left over matched the charging power 'within reason'. I'm pretty sure the Chargeverter efficiency (88.5% in this case) is reasonable based on previous tests using 240v and the IotaWatt total AC power number of 4.14kWh.

Likely the largest source of error was the scale - weighing the 30lb propane tank before and after and using 4.11gal / pound. Ambient was ~60F.

Personally, my big takeaway is that even if the numbers are a bit high a propane enhanced eu3000is worked! The Honda ran solidly for 99minutes producing good charge. The max rating currently listed for an eu3000is is 2800w sustained (on gasoline) and it sure looked like it was putting out ~2,569w 'sustained' (per IotaWatt) which is close enough to the 2800w to confirm that propane is a viable approach power wise.

I fount this link - https://learnmetrics.com/how-much-propane-do-generators-use-per-hour/ - which talks about generator / propane efficiency with numbers. Here's a snippet showing 22.3% efficiency at 100% rated load on a Generac. The eu3000is in this test was at 91% rated load, so 21-22% is not impossible but I agree that 23.4% is likely too high.

 

[OffGridInTheCity]

Just got in a MaxPeedingRods MXR4000GT - https://www.amazon.com/dp/B0CQ21P1BT - upgrade for my camper.



Fired right up on propane and gas - no issues.

Did a gasoline test -> Chargerver V1 set to 41a'ish -> 48v powerwall.....
Put in 1 quart to dry gen and it only ran 11mins... but figured that was filling the system and let it run dry. Then put in 2 quarts = 0.5gal and got 2.9kwh in just over an hour.

This test indicates 5.8kwh / gallon -> Chargeverter V1 and at 90% Chargeverter efficiency that's 5.2kwh of charge to the battery / gallon. Note my home is at 1,400ft elevation which is 'per docs' there's a 4.5% loss of power for each 1000ft of elevation

Here's the Iotawatt graph of the 0.5gal run -> Chargerverter V1 at 41a @ ~53v battery.