Would double battery = double mileage?

[Christ]

Originally Posted by jamesqf

Suppose it's not a few long trips per year? Suppose you have an EV with (just for instance) an 80 mile electric range, and you regularly make trips of 100 miles. So you drive 4/5 of the way on electricity* and 1/5 on the generator: even if the generator is only half as efficient as using a plain IC-engined car, aren't you still cutting fuel use by 60%?

*Though of course you would not really run the batteries to empty, then run a generator big enough to drive the car, but instead would have a much smaller generator running most of the time.

In this case, an ICE that only operates at 80% load, with e motor assist, recharged by braking, either using the pedal or engine braking, and no option to idle.

This removes the charge inefficiency, and allows "normal use" operation.

Inherent problem that if the batt pack runs dry, the power of the motor driving would sort of "limp home". A10hp ICE isn't going to be hugely fast.

However, given the immediate resources of the average ecomodder in time, money, and skills, a generator is simply easy, fairly inexpensive, and workable solution to range problems.

[IamIan]

Originally Posted by jamesqf

Suppose it's not a few long trips per year? Suppose you have an EV with (just for instance) an 80 mile electric range, and you regularly make trips of 100 miles. So you drive 4/5 of the way on electricity* and 1/5 on the generator: even if the generator is only half as efficient as using a plain IC-engined car, aren't you still cutting fuel use by 60%?

*Though of course you would not really run the batteries to empty, then run a generator big enough to drive the car, but instead would have a much smaller generator running most of the time.

I only see it as a ~60% ICE Fuel savings if:

• ICE only provides energy for 1/5 of distance
• Generator ICE is equally as efficient as the ICE it replaces.
• ~90% efficient Generator
• ~90% efficient Control Electronics
• ~90% efficient Motor
• None of the generator electricity gets buffered by the batteries

If you buffer the generator through the batteries I see it closer to ~47% ICE Fuel Savings ... If:

• All above
• ~90% efficient battery cycle Charge to discharge
• ~90% efficient 2nd set of control electronics

In your example trip the battery is already providing 4/5 = 80% of the energy for the trip.

60% less ICE fuel + 80% of Trip from Battery = 120% of original energy ... a ~20% efficiency loss.

47% less ICE fuel + 80% of Trip from Battery = 133% of original energy ... a ~33% efficiency loss.

Even if the Generator ICE can be operated more efficiently than the ICE it replaces ... how much more efficient would we expect the ICE generator to be ??? Could we expect more than a ~33% increase in average ICE operating efficiency? ... that seem optimistic to me.

- - - -
My perspective:
The additional size and weight of the ICE means giving up ~50 Miles worth of battery space and weight ... if you are only need another ~20 Miles adding more batteries will be smaller , lighter , and give better vehicle energy efficiency than adding the ICE Generator.

[codenamezero]

Don't forget that, with your example, you will be dragging a 300lbs+ dead weight with your ICE for the entire duration of the 100 miles, and only 20 miles will the ICE be operating... Not only the ICE pusher will obviously consume much more fuel when operating vs 200cc generator, it will be a huge dead weight EVERYWHERE you go as well.

[Christ]

Yup, still siding with a 5kw genset.

Especially a diesel one, because of the available "freebie" fuels.

[Joenavy85]

here you go

Building a high power AC/DC generator system!

[jamesqf]

Originally Posted by IamIan

Even if the Generator ICE can be operated more efficiently than the ICE it replaces ... how much more efficient would we expect the ICE generator to be ???

I think you could expect quite a bit of efficiency increase. Remember that the engine in a conventional car has to be considerably oversized WRT the power needed for cruising at highway speeds, so much of the time it's operating far from its most efficient point. The generator's engine can be much smaller, because batteries provide for acceleration, and can always be run at max efficiency. Plus you have another efficiency (and performance/handling) gain, because you don't have to haul around a massive battery pack to get acceptable range. Look at the Tesla, which is about 700 lbs heavier than the Lotus Elise it was derived from.

The point, though, is that instead of a pure electric with a hard range limit (so if your batteries are drained miles from the nearest outlet, you're stranded), you have one that's much more efficient than an IC engined car, while still having virtually unlimited range.

[bwilson4web]

Compare two, 2010 model year vehicles:

• A - 115.3 cu.ft., 51/48 MPG, 134 hp @5200 rpm, 3042 lbs, 48.9(147) MPG
• B - 115.9 cu.ft., 22/33 MPG, 179 hp @6000 rpm, 3285 lbs, 26.9(15) MPG

Bob Wilson

[JasonG]

Originally Posted by Christ

Hyundai DHY6000SE Silent diesel generator, 5200w, electric start, 230v, 115v

Fuel consumption: .75 - 2 liters/hour, depending on load.

Max continuous output - 4500w

That's what, about 6.5hp? Not quite enough to drive the car at 60mph on it's own, but the 60mph figure for mpg at 2lph:

60 miles using .52gal - 100mpg?

Cost is 1318 British pounds = 2 132.1286 U.S. dollars.

Granted, that's a diesel... Didn't figure they were 10x more efficient than your kohler...

Thanks for catching that Christ.
I accidentally looked at the useage for the 50KW !!

Off the cuff, bumping to a 8.5KW might be enough to hold 60MPH ?
If the cd was in the high teens, it would do it.

[Frank Lee]

From what I've seen similar new gens in the U.S. go for $780 on up.

Kipor KDE5000E Professional Series Generator 5000 Watt 120V 60Hz Single Phase Diesel Single Cylinder Generator Camper Trailer RV

Originally Posted by codename

Not only the ICE pusher will obviously consume much more fuel when operating vs 200cc generator, it will be a huge dead weight EVERYWHERE you go as well.

I don't think it would consume more fuel vs genset because of the system efficiencies.

Any range extender you are pondering is going to add weight- I thought the plan was to only strap it on when embarking on long trips?

Originally Posted by james

I think you could expect quite a bit of efficiency increase. Remember that the engine in a conventional car has to be considerably oversized WRT the power needed for cruising at highway speeds, so much of the time it's operating far from its most efficient point. The generator's engine can be much smaller, because batteries provide for acceleration, and can always be run at max efficiency. Plus you have another efficiency (and performance/handling) gain, because you don't have to haul around a massive battery pack to get acceptable range. Look at the Tesla, which is about 700 lbs heavier than the Lotus Elise it was derived from.

The point, though, is that instead of a pure electric with a hard range limit (so if your batteries are drained miles from the nearest outlet, you're stranded), you have one that's much more efficient than an IC engined car, while still having virtually unlimited range.

So size the engine in the pusher to operate at that efficiency zone and bypass all the conversion deficiencies in mech/elec.

Re: weight: the purpose of this thing isn't for city driving all day long. I thought it was for a long trip? I presume that is highway. Weight isn't much of a factor for steady state cruising.

Sounds like what the guy needs is a Volt.

[Angmaar]

Where do you need to go that's over 200 miles away?