Pro Power Gallons per kWh

[fwunder]

I apologize if this has been asked and answered. I have done numerous "Distance to Empty" tests myself and have searched the forums and always come up with observed DTE data. Has anyone actually seen any data that can equate kilowatt hour usage of the 7.2 kW system to actual fuel used? It's definitely not a linear scale based on Ford's 7.2 kW 32 hours @ full load statement.

Running my house ( 10 circuits ) or my TT ( Alde Heat in freezing temps or Dometic Cool Cat in +85 ) I can observe about 25-35 miles "DTE" use over 12 hours.

Just back of the envelope calculation based on observation I come up with .11 gal./kWh or about 1.8 gallons @ 12 hours using on average about 1.55 kW/hr

It's easy to measure kWh. Just curious if anyone has any real data - gal/kWh?

Thanks

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[Henfield]

actual demand will determine consumption. A typical 7k home generator runs about 1 to 1.25 gallons an hour at full "buzz".

 

[Spiffy]

I don't have exact data for you but I did a test.
I connected my propower to my house at midnight. So the truck ran my house. Lights, stove, audio system, everything I do normally.
I disconnected at midnight the next day. Yep I go to bed late.
I filled my truck up. I used 1.5 gallons.
If I had been running my generator like I did during the last ice storm I used 11.5 gallons and had to shut it down because of noise.
It's impossible to calculate hiw much gas you will use. My house has Gas appliances, I have led lights, my biggest draw is my 72inch TV and my extensive audio amps that are always on. My tube Amp pulls 11 amps always. The tubes are Uber extensive and hate hot cold cycles. I don't have a wife that's blasting hair dryers and was always cold . Space heaters!!! So I figured I could afford the electric expense of the tubes.

Anyway if your house was electric heated or you wanted to run AC you woukd use more.

FYI I just replaced my hvac system. I checked my current draw from the new AC compressor. It's variable but at startup it pulls 13amps@220v
When the house stableizes it pulls 8amps.
Amazing difference. These new variable scroll compressors are awesome. Even at high output I can't hear it running other than a light fan noise.
But it cost me 11k to replace everything. I don't want to know my rate of recovery.
So calculating my total draw even with AC my propower will handle it.
BTW the AC is soft start. No sudden demand. My last AC demanded 30 amps for 1 second.

Good news is the propower inverter is super clean. As it should be. It's getting its food from batteries. I wouldn't dare to run my audo amps from the gas generator directly. My audio system is isolated by a 1200kw apc conditioning.

 

[fwunder]

I guess the better question to ask is at percentage of rated power, what is the fuel efficiency?

@ 50% load - 3600 W
@ 25% load - 1800 W

An interesting table listing the fuel efficiency of a number of generators can be found here:

https://www.batteryequivalents.com/most-fuel-efficient-generators.html

Note that the Honda EB6500n is rated @ .23 gal/kWh @ 50% - 2750 W

Very impressive, but not as impressive as our trucks, I think.

I think the PB would compare very favorably with many!

Thanks.

 

[Spiffy]

I find it fishy that they all rate at 50% duty. There is diminishing returns as the load goes up. You woukd think if a generator uses 1.2 gph at 50% it woukd be 2.4 at 100%
In real life that's not true.
I have a airplane that has an o360 Lycoming engine. We calculate fuel use by time. Every Lycoming engine uses 10.3 gal per hour at full trimed out power. Trimed out Is mixture adjusted for peak exhaust temperature.
If I drop my throttle to 50% my fuel flow is 4.1 gph. Our fuel flow calculators are extremely accurate.
So I know that's not a generator engine but that gives to show that fuel flow is no linear. Its always an advantage to show rated fuel use at 50%

My experiment is total use in 24 hours. Sometimes a high demand and sometimes low. The benefits of propower is its always at peak efficiency. Low demand = no engine. High demand = more run time.

The only way to real time Data is by doing exact fuel use with a calibrated load. Then it's going to take a set oeriod of time. 24 hours is OK but just OK.
I don't think anyone here has actually done that. It would take at least 3 days or 4.
25% @ 24 hrs. 50% @ 24hrs 75% @ 24hrs and so on.
It would be a interesting experiment for me.
I have the ability to measure accurate loads on electrical systems. I design and build airplanes and need to know exact loads on the different circuits. For example how long will my reserve battery last if I have an alternator failure. What circuits to shed to keep my navigation and communications operational. I start shedding all non essentials. High priority is fuel pump, navigation/autopilot, coms, navigation lights, strobes, calculate the lowest voltage each device will operate on and record the time to that hard line with each one being shed. Takes a long time. Days. You can calculate by manufacturer data but it doesn't account for resistance through relays, copper, heat or cold.

I might just do that for you.

What load data are you wanting 50% and 100%

 

[fwunder]

It would be an interesting experiment! I was hoping someone had already done it!

BTW, I have to take exception with you're point:

"Low demand = no engine."

I'm sure you know that even with no load on the generator, the ICE will still cycle. I have measured and others have also, that there is about a 400 watt load with "nothing" apparently running.

It's kinds fun to watch the HV SOC drop to 40% when ICE kicks in even though you might think nothing is running. I have even tried ( unsuccessfully ) to feed amps to the HV battery ( solar ) to avoid or reduce ICE cycles.

Kinda fun reading your airplane experience. I used to drive yachts ( deliveries ) that had to fuel gauge(s). Did have engine hours, though. That's how we judged fuel.

 

[fwunder]

Just to continue....

If you could measure fuel flow, why would you need multiple days?

If we could measure fuel flow @ 1000 watts, fuel flow @ 1500 watts, fuel flow @ 2500 watts, etc.; could we not create a curve ( yes, I know it would not be linear ) to plot energy vs. fuel usage?

Thanks! Fun!

 

[fwunder]

Whoops! Of course, we have to throw in the HV battery capacity and depletion rate at various power loads. There must be an equation somewhere!

 

[fwunder]

...and another equation for charging rate while under load. Yike!! Nevermind.

As you say, best to just put various loads on and measure fuel consumption over time.

Sorry for thinking out loud.

 

[Samson16]

There was a cool anecdotal video where a Tesla model 3 was charged with a powerboost. Full 3600 x 2 and the PB delivered without tripping. They showed how much fuel was consumed by the PB and how much power was delivered to the Tesla. I can't find it now lol.

 

[fwunder]

Thanks Samson16. I have seen that. But what about 48 hours @ 1800 watts - 1.8 kWh? How much fuel? Thanks.

 

[EricR]

I find it fishy that they all rate at 50% duty. There is diminishing returns as the load goes up. You woukd think if a generator uses 1.2 gph at 50% it woukd be 2.4 at 100%
In real life that's not true.
I have a airplane that has an o360 Lycoming engine. We calculate fuel use by time. Every Lycoming engine uses 10.3 gal per hour at full trimed out power. Trimed out Is mixture adjusted for peak exhaust temperature.
If I drop my throttle to 50% my fuel flow is 4.1 gph. Our fuel flow calculators are extremely accurate.
So I know that's not a generator engine but that gives to show that fuel flow is no linear. Its always an advantage to show rated fuel use at 50%

My experiment is total use in 24 hours. Sometimes a high demand and sometimes low. The benefits of propower is its always at peak efficiency. Low demand = no engine. High demand = more run time.

The only way to real time Data is by doing exact fuel use with a calibrated load. Then it's going to take a set oeriod of time. 24 hours is OK but just OK.
I don't think anyone here has actually done that. It would take at least 3 days or 4.
25% @ 24 hrs. 50% @ 24hrs 75% @ 24hrs and so on.
It would be a interesting experiment for me.
I have the ability to measure accurate loads on electrical systems. I design and build airplanes and need to know exact loads on the different circuits. For example how long will my reserve battery last if I have an alternator failure. What circuits to shed to keep my navigation and communications operational. I start shedding all non essentials. High priority is fuel pump, navigation/autopilot, coms, navigation lights, strobes, calculate the lowest voltage each device will operate on and record the time to that hard line with each one being shed. Takes a long time. Days. You can calculate by manufacturer data but it doesn't account for resistance through relays, copper, heat or cold.

I might just do that for you.

What load data are you wanting 50% and 100%

Many of us would appreciate this, if you choose to do so.

There is no substitute for expertise!

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