Would double battery = double mileage?
 

Got a question about pure electric car (EV), their mileage kind a sucks right now, like 200-250 miles per charge. I'm wondering, if i can retrofit/double the capacity of the battery pack (like build a layer and leave them at the trunk), won't it effectively double the mileage it can go (ignoring the weight factor here)?

What i have in mind is that... Honda Fit is coming out with an EV next year, and i'm thinking perhaps i could just use the stock battery for daily commute, but when i need to do long trip (say 400-500 mileage range), i could flip down the backseats and load an extra battery pack into it...

Also, you know those gasoline electric generator... what if i run a small generator in the trunk, with crazy sound isolation, won't it be able to charge the battery faster/enough to make it go further? So instead of loading a battery pack, i could temporarily pop-in a portable generator to continuously charge it while i drive.

Just throwing out ideas.

...unfortunately, their additional WEIGHT would hold you back from ever achieving the 2X-milage that you assume they'd provide.

Yea, I did said "ignoring the weight factor" though...
Which is why i also think of the portable generator method, but that won't be as green as the added battery of course.

I'm thinking since the EV already have a battery charging inlet, it should be quite easy to tap the wire and just hook up the portable generator to the existing wire to charge it. Something like this perhaps? Honda EU2000i

I read it else where that the EV require 240v/16amp (some uses higher amp like 40) to charge, i think what's important is the amp?

Actually, i just discovered that using a portable generator method had already been done like 10 years ago! :O
A Portable Generator in Your Electric Car

The amp rating is what is required on the circuit at that voltage to keep you from blowing a breaker.

You can charge with a generator on the fly, but you'll want to isolate where the generator rests in the vehicle, for exhaust fumes. Generators are also generally air cooled, although forced air, and will require d some fresh air source.

Good idea would be to charge on your rest stops, and stop about every 2 hours for 30 minutes.

Of course, you probably won't do that, so just make sure you properly vent the generator, out run it behind the car in open air.

In some states, a generator trailer doesn't need to be registered, which means you get some extra storage space, as well.

It would be nice to see you build the generator as a boat tail extension to the rear of you car. And maybe go with steam, that might make it possible to use fuels that are both free and renewable.

and how would you get the steam? build a fire in the space to boil water?

Suggesting that ...motors... don't already produce enough heat to generate steam?

Even electric motors, under load, generate quite a bit of heat. Maybe not enough to replace a fueled generator, but still something to extend range.

the cars can produce steam from water. but no where near the volume needed to make any returns. power generation is my field of work so i think looking at a car. Putting a low RPM high output wind generator linked to the output shaft of a turbo would but out more. then again the returns would not really worth it on the return. but then again every little bit helps.

It is 2011 and we are talking about adding portable generators to EVs? :confused:

...so, was 2010, the year-of-the-extension cord?

What is the point of that comment? Unless you have a palm size nuclear reactor, I don't think there are any other economic way of increasing the battery capacity or generate more power.

I did also think of converting the entire roof top of the car into full solar panel, but that means we will need to cut the car open, and fab cost will be expensive. Plus it is unlikely that solar panel will generate nearly as much as a gasoline generator could.

As for the other poster, regarding to the fume issue, I don't think it will be a problem at all. I have been modifying my integra for a ling time, and I know most cars it usually have a vent at the back of the trunk area to allow interior pressure escapes, so I think we could easily route the fume out from there.

As for the idea of using steam, I have no idea what you guys are talking about lol, sound a bit messy?

Nobody remembers all the conversations about how inefficient it is to burn gas to turn generators to make electricity to charge batteries and/or power electrics motors, instead of just using the gas to make the whole mess go down the road? :confused:

...in Franks' defense: does that simple fact that "...90% of 90% equals 81%..." ring any cranium bells?

So how would you generate electricity then? The only other alternative energy source are:

• solar power
• wind power
• hydrogen fuel
• nuclear power
• steam power (as other suggested)
• gasoline

solar not powerful enough
wind you have to be moving
hydrogen, i won't think i will be playing with hydrogen
palm size nuclear, yea right... in 50 years?
steam power, show me an example of using the electric motor's heat to boil the water into steam then convert the steam into power, otherwise this is just way too inefficient.

so the only other option to GENERATE power, is using gasoline...

What exactly is going to drive the turbo in an ev?

Frank, the point was using something that's already an ev, and reliably making it have an extended range when necessary.

Nobody is talking about making a car that always runs on a generator, or any thing like that.

Doubling the battery pack size isn't viable for several reasons, including weight/vehicle capacity, and shelf life of the batteries when they're not being used.

A generator is relatively cheap, and has an alternative use, and probably weighs less than 250 miles worth of batteries anyway.

While backing Frank (as usual) didn't Metro or was it Paul do that for the "Instructables" contest ?

Remember all the ruckus about Chevy Volt and how their propaganda machine said the genset would only generate electricity, but then the real thing used the ICE to directly power the wheels? Chevy did the right thing.

The options I would pursue would be either a battery trailer or an ICE pusher trailer. (P.S. Or have an ICE long distance cruiser). Perhaps another use could be made of the battery trailer when not used on the road- power the house fr'instance. Then there's the ICE pusher, which has been done with what I understand are good results. Then you have virtually unlimited range and you won't ever have to sit there and wait for it to charge the battery pack up either. Either way, the portable generator route is pretty much the least efficient way to put the juice back in the boxes.

If this whole thing isn't about efficiency, then what is it?

So for a few long trips a year, its better to buy, register, and insure another car?

Build a heavy battery trailer to pull around, including registration and the cost of another battery pack? Power the house? Where do they recharge from?

Buy a parts car from which one could build a pusher with an ICE, including conversion expenses, and registration?

5 kw generator, used for less than $1000, no registration, no trailer, only basic maintenance costs, and alternative use as a HPU when the power goes out...

I know my choice...

I understand what Chevy did, and for them, it was the right choice. Were talking about an EV that already exists, and is driven, and making a simple way to extend the range of it. Cost of mods, as always, is something to consider, even though some don't think so.

Point 1
For $1000, Craigslist has lots of nice cars around here.


Point 2
A 5KW genset running flat out burns 4-5 gal an hour (mine in the sig pic is a 2006 Kohler) that's 10-15MPG @ 60MPH. Heck, the truck pulling the 40 footer can beat that.

Another car? You bet! Especially considering how numerous those trips will probably be. Could have a '91 or older subcompact with collector plates on it (like certain Tempos I know of) only activate the insurance when it's gonna be used, pick it up (or already own it?) for dirt cheap (I won't launch into my success at finding those again).

No, build a light battery trailer :) Or just go get one from Harbor Freight for cheap.

They can recharge from wind or solar I reckon. Or not mess with it and go ICE.

Yes. Buy a wreck that would make a good ICE trailer. You got it! :thumbup: I wonder if it would qualify for the same sort of permanent registration my HF trailer has? That's a small one-time fee.

Someone should charge up an EV battery bank with a portable generator sometime and let us know how long it takes and how much gas it uses.

4-5 gal/hr? Something doesn't sound right about that?

In any event, here, a trailer is $6/year to register.

Classic and antique plates come with restrictions, usually barring them from long trips or frequent leisure use.

If you don't have insurance, you must turn in your plates. Your driving privilege can be suspended if you don't.

If the trips occur more frequently than a couple times a year, it's probably worth looking into those options. Once or twice a year, I'll just use the generator I already have, and stop for a charge once in awhile.

You could do the math for a pack that goes 250 miles on a charge and figure out how long it would take to charge with a 5kw genset. Nominal output on mine was around 4250w continuous. I never ran it long enough at high output to pay attention to consumption.

Oh wow, i had no idea about the ICE pusher concept, thanks for the input.
I've just googled it now, and that's an interesting idea. Interesting, but after analysed the cons, I think ICE pusher is far from cost effective and far from environmental friendly though...

Here is why:

• All the hassles that Christ mentioned above
• The money to purchse used or scrapped car with a running engine, $500?
• Time and money to make the pusher, DIY will be cheaper, paying someone to do it would be expensive
• Ugly, dragging such a weird thing at the back is not visually appealing
• Not aerodynamic, extra wheel drag
• Dead weight, the pusher itself weight more than a 5kW generator
• Pollution, the ICE pusher, I'm sure it won't be a 2010 < 1.5L small displacement engine, and most likely off some scraped 2000 car... and the displacement will most likely 1.8L+

Even if i buy 2x brand new Honda EU2000i, it will only be 200cc (2x98cc), 1.1 gal/ 4 hrs = 0.25 gal/hr x 2 = 0.5 gal / hr max, and it will give me 4kW, and will cost me 2500$.

Building an ICE, will most likely cost you 1500$ minimum.

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...

Here, this reply from the another Ecomodder thread stated clearly the drawback of the ICE pusher. http://ecomodder.com/forum/showthrea....html#post1446

After everyone's input, i think adding additional battery into an EV would not be viable... I think having an electric generator would be the way to go...

I also have this concept of a underbody air turbine electric generator... wonder if this concept would work. Basically installing a brunch of small turbine at the end of the car, at the rear diffuser area...

http://2.bp.blogspot.com/_QLoH0OqxER...arDiffuser.jpg

^ At the spot where it begin to curve up, we install 2 rows of small air turbine, so as the car move, it would generate electricity, but i doubt this would generate much power.... lol

Saw an interesting quote from a physic forum:

It would likely increase drag, defeating itself by magnitudes.

The charging energy needs to come from somewhere.

The cops never look twice at collector plates. In fact it was a cop that told me to get them after he busted me for expired tabs on my collector car.

Well go ahead and try the generator; personally that would be my last choice. If I was willing to sit around at various points during the trip to wait for a charge, I'd just pack an extension cord and glom onto someone's unguarded outlet for a while. ;)

No, they didn't.
Because they use the ICE to both drive the car itself, and fill the batteries, it's way oversized as a generator.

Audi is going for a small, compact wankel in their electric A1.
I expect it to be somewhere in the 150-250 cc (equivalent) bracket.
15 kW would easily keep that small car going.

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.

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.

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.

Yup, still siding with a 5kw genset.

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

here you go

Building a high power AC/DC generator system!

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.

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

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.

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

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?

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.

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