Charging While Driving w/ Gas Generator in Bed (Range Extender for F-150 Lightning) - Testing

[Firn]

Yeah prime power generators are enormous. It just speaks to the different longevity and duty of a generator meant to run 100% duty, versus a little portable generator meant to be used every once in a while. I figure these portable generators when ran hard are probably good for less than 1000 hours of operation before they are trash.

The math for sustained power usage in the truck is really easy It's just your speed divided by your efficiency. So, if you are going 70 mph at 1.8 efficiency That means your truck was using a sustained 38kW to drive at 70mph. Dropping just 5mph would make a huge difference; you can see the non-linearity because you've got two factors, both helping as you slow down.

Still, if you were able to generate half of your sustained driving load you would double your range. Yeah, no way you're generating 19kW for 10 hours straight without stopping for fuel. But that's the beauty of a generator for interstate travel, you can stop at any gas station and in 5minutes you're back on the highway. I'm working on getting a water cooled diesel generator right now that is small form factor and can fit in the back and I'm planning to try and harvest the heat from it this winter and do more testing. Small generators are like 30% efficient so if I could use the waste heat that would really be nice.

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[PJnc284]

The SR maxes out at 48 amps but good comparison

 

[P-38]

What percentage of the battery are you using for your graphs?

 

[PJnc284]

100% would be my guess.

 

[ElectrifyingMe25]

Not at this


Not at this time. It's about $500 in parts and the market research I've done just doesn't show demand.

You are doing a great job. There will be people like us who purchase your kit.

It's great that you've enginered this option.

Thanks.

 

[P-38]

100% would be my guess.

100% should have orange line crossing 2.0 mi/kWh at 262 miles for the ER (2 x 131). It looks like it crosses at 210 which would be closer to 80%. Rather than ASSume I asked.

 

[ZSC100]

Why are you using only 80% of the battery's capacity for your range calcs? I know if I'm taking a road trip and I've loaded a generator, I flip open my app and charge that bitch to 100%. This assumes that I'm not traveling over my total range and hitting fast chargers, I guess if you were still planning to stop and fast charge 80% would be reasonable, but remember, your range anxiety should be lowered drastically b/c you have a generator on board. If you are cutting it close to reach a fast charger just slow down a bit and if absolutely necessary slow down to a unity drive-charge magic point and your mileage is indefinite. For my XLT charging at 11kW, that happens at 35mph/3.1mi/kWh = 11kW. So at 35mph range is infinity.

 

[PJnc284]

Why are you using only 80% of the battery's capacity for your range calcs? I know if I'm taking a road trip and I've loaded a generator, I flip open my app and charge that bitch to 100%. This assumes that I'm not traveling over my total range and hitting fast chargers, I guess if you were still planning to stop and fast charge 80% would be reasonable, but remember, your range anxiety should be lowered drastically b/c you have a generator on board. If you are cutting it close to reach a fast charger just slow down a bit and if absolutely necessary slow down to a unity drive-charge magic point and your mileage is indefinite. For my XLT charging at 11kW, that happens at 35mph/3.1mi/kWh = 11kW. So at 35mph range is infinity.

80% gives a better idea on an actual road trip since most aren't charging above 80% after inital discharge due to the time penalty.

100% should have orange line crossing 2.0 mi/kWh at 262 miles for the ER (2 x 131). It looks like it crosses at 210 which would be closer to 80%. Rather than ASSume I asked.

yeah that makes more sense.

 

[ZSC100]

Something is still not right, Knowing your range requires solving for two variables.


For my truck using 70mph and 2.0mi/kWh with a usable battery capacity of 94kWh it solves out to be:
https://www.wolframalpha.com/input?i=G+=+2.0+*+(t+*+11+++94),+G+=+t+*+70


t = 3.9hr
R = 274mi

 

[PJnc284]

Below assumes the 9.5kW net you had and a rate of 1.5gal/hr since you used 3 gallons over 2 hours on that trip. No degradation

100%

Speed (mph)​	mi/kWh (no gen)​	Range (mi, no gen)​	Drive Power (kW)​	Net Drain (kW)​	mi/kWh (with gen)​	Range (mi, with gen)​	Generator hrs​	Gallons Used​	​
55​	2.6​	255​	21.2​	11.7​	4.7​	460​	8.4​	12.6​	​
65​	2.1​	206​	31.0​	21.5​	3.0​	294​	4.5​	6.8​	​
70​	1.9​	186​	36.8​	27.3​	2.6​	253​	3.6​	5.4​	​
75​	1.7​	167​	44.1​	34.6​	2.2​	215​	2.9​	4.3​	​
80​	1.5​	147​	53.3​	43.8​	1.8​	176​	2.2​	3.3​	​

80%

Speed (mph)​	mi/kWh (no gen)​	Range (mi, no gen)​	Drive Power (kW)​	Net Drain (kW)​	mi/kWh (with gen)​	Range (mi, with gen)​	Generator hrs​	Gallons Used​	​
55​	2.6​	204​	21.2​	11.7​	4.7​	369​	6.7​	10.0​	​
65​	2.1​	165​	31.0​	21.5​	3.0​	236​	3.6​	5.4​	​
70​	1.9​	149​	36.8​	27.3​	2.6​	204​	2.9​	4.4​	​
75​	1.7​	133​	44.1​	34.6​	2.2​	173​	2.3​	3.5​	​
80​	1.5​	118​	53.3​	43.8​	1.8​	141​	1.8​	2.8​	​

 

[Firn]

What percentage of the battery are you using for your graphs?

80% iirc

 

[Firn]

Why are you using only 80% of the battery's capacity for your range calcs? I know if I'm taking a road trip and I've loaded a generator, I flip open my app and charge that bitch to 100%. This assumes that I'm not traveling over my total range and hitting fast chargers, I guess if you were still planning to stop and fast charge 80% would be reasonable, but remember, your range anxiety should be lowered drastically b/c you have a generator on board. If you are cutting it close to reach a fast charger just slow down a bit and if absolutely necessary slow down to a unity drive-charge magic point and your mileage is indefinite. For my XLT charging at 11kW, that happens at 35mph/3.1mi/kWh = 11kW. So at 35mph range is infinity.

Because if I'm worried about distance I'm worried about far more than a single charge/generetor section. That 80% would be down to 10% to give a bit of space for bad chargers, etc and then up to 90% which is still WELL into where the charge rate drops off.

 

[ZSC100]

Because if I'm worried about distance I'm worried about far more than a single charge/generetor section. That 80% would be down to 10% to give a bit of space for bad chargers, etc and then up to 90% which is still WELL into where the charge rate drops off.

OK, fair enough, but something is still wrong with your #'s, I'd like to see graphs that somehow relate speed in a human-understandable form, maybe just list them in parenthesis next to the X axis labels. We know speed and efficiency are linked, and we know what they are under normal conditions, maybe just show them for what your experience/guess is. Here are 2 data points from my experience that should anchor your plots.

For an SR CWD @ 11kW power unity happens at 35mph / 3.1mi/kWhr
For an ER CWD @ 19kW power unity happens at 50mph / 2.6mi/kWhr

 

[Firn]

OK, fair enough, but something is still wrong with your #'s, I'd like to see graphs that somehow relate speed in a human-understandable form, maybe just list them in parenthesis next to the X axis labels. We know speed and efficiency are linked, and we know what they are under normal conditions, maybe just show them for what your experience/guess is. Here are 2 data points from my experience that should anchor your plots.

For an SR CWD @ 11kW power unity happens at 35mph / 3.1mi/kWhr
For an ER CWD @ 19kW power unity happens at 50mph / 2.6mi/kWhr

I understand what you are saying eith regard to speed but I don't think it is a good metric here due to the immense variation in efficiencies that can happen.

We have a general sense of how efficiency and speed related but it does have immense variation. Specifically weight, temp, weather, and towing, all of which will dramatically affect the efficiency calc. If we say it extends range by 50% at 60mph (just throwing numbers here) then that would mandate a certain efficiency at 60mph to be valid and it would not be valid for any other efficiency value (aka towing, or winter, etc).

.
Unity shouldn't change based upon battery size, it should only change based upon efficiency, and the two battery sizes have near enough efficiency. Unity means input equals draw and our "efficiency" in this case is the draw on the system.

 

[ZSC100]

I understand what you are saying eith regard to speed but I don't think it is a good metric here due to the immense variation in efficiencies that can happen.

We have a general sense of how efficiency and speed related but it does have immense variation. Specifically weight, temp, weather, and towing, all of which will dramatically affect the efficiency calc. If we say it extends range by 50% at 60mph (just throwing numbers here) then that would mandate a certain efficiency at 60mph to be valid and it would not be valid for any other efficiency value (aka towing, or winter, etc).

.
Unity shouldn't change based upon battery size, it should only change based upon efficiency, and the two battery sizes have near enough efficiency. Unity means input equals draw and our "efficiency" in this case is the draw on the system.

Correct the only reason unity is different is because the SR can charge at 11kW and the ER can charge at 19kW, You're correct it has nothing to do with battery size, but range does. And of course there are different efficiencies given different speeds for different conditions. All Lightning owners know that, that's why your range is half when pulling a trailer,,,,,,, given the same speed.

Something still isn't right about your #'s, show what equations you're using for the plots.

Here is an ER with 80% of battery getting 2.0mi/kWhr going 70 with 19kW of CWD:
https://www.wolframalpha.com/input?i=R+=+2.0+*+(t+*+19+++(0.8*131)),+R+=+t+*+70
Range = 458mi

If you were towing with the same truck at the same speed with 19kW of CWD plug in 1.3mi/kWhr and you get:
https://www.wolframalpha.com/input?i=R+=+1.3+*+(t+*+19+++(0.8*131)),+R+=+t+*+70
Range = 210mi

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