Would double battery = double mileage?

[gone-ot]

...seeing as how Hydrogen (H2) *gas* is lighter than air, doubling it's amount should make the vehicle actually lighter, weight-wise!

...of course, if it's LH2 (Liquid Hydrogen) being used, only benefit I could see would be 'super chilling' your Bud's alot faster!

[roosterk0031]

Add a 1 1/4" reciever hitch $100, a hitch buddy $100 and strap down the generator $500, pull over start generator when needing to recharge and your on your way, or could go electric start generator so can start and stop on fly, but it will cost more & weigh more and may go over the tongue weight of car.

[dcb]

...and enjoy your 10mpg extended range.

i.e. 7.5kwh kohler runs at 1.4gph, times charging losses, times discharging losses, times controller losses, times motor losses, before you get to an actual output shaft that can turn a wheel.

If you are wondering, the bsfc there, measured at the generator output, is about 523g/kwh, compared to something like a metro or saturn which peaks at 250g/kwh and whos bsfc charts don't even show an isobar for anything in the 500 range.

[jamesqf]

Originally Posted by dcb

.i.e. 7.5kwh kohler runs at 1.4gph, times charging losses, times discharging losses, times controller losses, times motor losses, before you get to an actual output shaft that can turn a wheel.

Not if your system was designed sensibly: most of the power generated should go straight to the drive motor, with only the excess over the amount needed to move the car going to the batteries and incurring charge/discharge losses.

[dcb]

I will refrain from mentioning EPA considerations when motivating a vehicle, but a typical $500 generator is still not going to be a model of efficiency, still a very lossy proposition, and the jury still isn't impressed with the series/parallel volt.

"sensibly" means convert the gasoline into miles most efficiently, hard to do when you make the engine spin a generator to run a controller to run a motor, especially when you are already at 520ish g/kwh before you get to the controller.

The kohler is about 13.4hp. Which is maybe 10kw, so you lost %25 of your gas right there to make 7.5kw, let me know when this is sensible.

[IamIan]

Originally Posted by jamesqf

Not if your system was designed sensibly: most of the power generated should go straight to the drive motor, with only the excess over the amount needed to move the car going to the batteries and incurring charge/discharge losses.

ICE output Mechanical power 100%
If 90% average operating efficiency Generator = 90% as electrical power
If 90% average operating efficiency control electronics = 81% as electrical power
If 90% average operating efficiency Motor = ~73% Mechanical power

~27% loss of mechanical energy / power.

Even if you managed to get the ICE on the generator operating at an average of 50% efficiency ( not going to happen ) ... the vehicle's energy efficiency is not operating any better than if a straight ICE-HEV were to run at 23% average operating efficiency ... it is very possible for the ICE-HEV to get better than 23% average operating efficiency , but getting the ICE generator better than 50% , is extremely difficult.

And that is without an additional two more steps of losses if you buffered into the battery.

It can be a convenience ... and offer peace of mind ... but energy efficient it is not.

[codenamezero]

Originally Posted by dcb

I will refrain from mentioning EPA considerations when motivating a vehicle, but a typical $500 generator is still not going to be a model of efficiency, still a very lossy proposition, and the jury still isn't impressed with the series/parallel volt.

I was thinking of the better ones like 2500$ 4kW Honda generator.

[dcb]

do the math... I have no idea which generator you mean, but it probably won't matter much.

[Frank Lee]

Article not regarding cars but analogous nonetheless:
Bike powered electricity generators are not sustainable | Energy Bulletin

[jamesqf]

Originally Posted by dcb

"sensibly" means convert the gasoline into miles most efficiently...

No, "sensibly" means minimizing the use of gasoline, while still keeping the benefits of unlimited range and not being stranded when the battery runs out. (Plus some minor benefits, such as being able to have heat in winter without cutting into range.)

So if I have a car with IC generator, and use electricity for say the first 40-50 miles of all trips, don't I reduce my gasoline usage considerably even if the generator is less efficient than using an IC-engined car? I can't see how it'd be otherwise under any reasonable set of circumstances.