# Question about using a gen to charge while driving.



## PaulDent (Aug 4, 2009)

I am doubtful that the battery problem will ever be completely solved to make EVs perform as well as gas. on range. The reason is, packing more and more chemical energy into a smaller size and weight is what making a bomb is all about.

On the otherhand, using a small diesel (or better still, a samll auxiiary gas turbine from an aircraft) to run at maximum efficiency and charge the battery, even while parked, is a possible way to go.

I don't know if this is accurate, but in school physics we learned that a steam engine was 10% efficient; a gasoline engine was 20% efficient; a diesel was 40% efficient and a gas turbine was 60% efficient. Hence the ides to use a small gas tubine running continuously at maximum efficiency to charge the battery while driving or parked. I have seen these small auxliary gas turbines from aircraft fairly cheap on E-bay. They drive an aircraft grade, 400Hz, 115-volt 3-phase alternator and you can get maybe as much as 20kw out of them.


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## Guest (Aug 4, 2009)

If you were to go with the diesel route your alternator would need to provide max pack voltage if you wanted to charge the pack too. Otherwise it would not be the best thing. The turbine is a fine idea and some turbines run on diesel or oil. Problem is heat and FOD. You must keep debris from entering the the turbine and that is the main reason turbines are not used. Any junk makes its way in can spell disaster for your little turbine. They have to be able to breath and the requirements are far more critical than with an internal combustion engine. 

I like the idea of a range extender bio-diesel powered generator that will power your motor. Hybrid. It can be done. You could even import a small 3 cylinder TDI motor from Europe and use that to power your generator and use the power to power up your electric drive motor. Make sure you have a good lithium pack to drive on electric alone and make it good enough to go further than 40 miles at 45 mph. Make sure you have a real nice looking vehicle to install it into. One that is efficient too. Plenty to choose from I think!


Pete 

Still I like the all electric and just plug in but may be a range extender trailer with a diesel engine and generator. No batteries and make it large enough to haul stuff too but easy to tow. Thinking of a small one for the ghia.


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## DIYguy (Sep 18, 2008)

I plan to have an option to pull one of these.................










mounted on a steering trailer, like this........











The welder puts out 8kw and is driven by a 20hp Kohler LPG engine. I will run 30 amps at 240 volts directly into my onboard charger... To extend range, when I want.

The rest of the time, it will serve as back up power for my house...oh yes, and a welder too!


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## PaulDent (Aug 4, 2009)

They tried using a gas turbine to drive a car in the 60's. The Rover company in England developed the Rover 2000 as the test bed for that. They abandoned the turbine, and I bought one with regular gas engine in 1966. The reasons they abandoned the turbine as direct drive were multiple: First, it doesn't like to start and stop, so stopping at lights and then accelerating away was a problem. Secondly, where do you blow the hot exhaust? Actually, they solved that with a ceramic heat exchanger. I had not heard of the problem of debris entering the air intake, but think that that would surely be solved with a suitable filter, like insect screen or finer. However, an even better solution might be a fuel cell. They also do not like to start and stop, so having a battery to absorb the output while stopped and provide a big kick for acceleration seems right. Fuel cells are getting more practical - there are various cells of residential size available - but they are not very flexible on fuel. At least they can run on propane or natural gas now, rather than just pure hydrogen.


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## Guest (Aug 6, 2009)

Running a turbine was suggested to operate a generator, not run the vehicle. A generator only needs to be run at a constant speed and the turbine would like that very much. Heat was a problem but damage to debris can be extensive. Turbines are very precise and must maintain that precision, small or large. A screen would be best but you'd have to keep that screen from being able to pick up and debris from the road or above. They are large vacuum cleaners and will suck any thing they can. FOD is a big problem. It was on of many and you pointed out some of the other. Slow to get started. No afterburners on those. They are however reliable if kept clean. A turbine to turn a generator need not be huge at all. In fact it could be quit small and could be made quite quiet. Get your hands on a small one and it would be worth the try. Blow the hot air up if need be. 


Pete


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## bbbowden (Apr 13, 2009)

Wouldn't it be cool to put one of these on a trailer:

http://www.microturbine.com/_docs/C30 Liquid Fuel.pdf


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## JRP3 (Mar 7, 2008)

PaulDent said:


> I am doubtful that the battery problem will ever be completely solved to make EVs perform as well as gas. on range. The reason is, packing more and more chemical energy into a smaller size and weight is what making a bomb is all about.


You mean like driving around with a tank full of energy dense gasoline? The nice thing about EV's is since the motor is so much more efficient than an ICE you don't need a battery as energy dense as gasoline or diesel. 200+ mile range EV is possible right now which means if all we do is come close to doubling the capacity of a battery we'll have all the density and range we'll ever need. Build a lighter weight more aerodynamic vehicle and you won't even need that.


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## Woodsmith (Jun 5, 2008)

It was something I have thought about too, to have a small genset to top up the battery charge to extend range.

However, I have been told that if I didn't carry the extra weight of the genset and fuel then I wouldn't need to extend the range either.

I was thinking about a built in generator inside the vehicle body so it would only be additional weight.
If you were to tow one on a trailer then you would have the extra aerodynamic drag and rolling resistence as well as the weight eating into your electrical range.

Also you don't get something for nothing so if you look at the capacity of your pack you will need to find a genset that was able to put that much capacity back in without having to wait 8 hours for it. That would be a big genset. It would also need to use fuel so you have fuel weight to allow for. Then there is the emissions and noise from the genset reving its head off charging your pack.

Given all that, if you needed that sort of range extension then you may as well buy a good factory design hybrid or even a very efficient ICE car. Mine gives me 60-65mpg on diesel.


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## JRP3 (Mar 7, 2008)

Putting the genset in the vehicle means you are always carrying around that weight, when most of the time you don't need it, plus it takes up room for batteries. With a trailer at least you only hook it up when needed. Genset trailers have been done successfully, though I agree for the most part you're better off sticking with an ICE or hybrid if you often need more range than a reasonable pack can give you.


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## DIYguy (Sep 18, 2008)

Lots of good points.... I have a few thoughts as it relates to my circumstances....



Woodsmith said:


> However, I have been told that if I didn't carry the extra weight of the genset and fuel then I wouldn't need to extend the range either.


Would be a more valid point if carried all the time...but is meant as an option in my case & would be used about 5% of the time I estimate.


Woodsmith said:


> I was thinking about a built in generator inside the vehicle body so it would only be additional weight.
> If you were to tow one on a trailer then you would have the extra aerodynamic drag and rolling resistence as well as the weight eating into your electrical range.


I started off thinking that I would have one in the back of my pickup...but thought more and realized it makes little sense to carry it all the time. I also use a truck a lot so I want the box space. For 5% time, it makes more sense for me to hook up when I need it. BTW, extra weight is also increased rolling resistance.....



Woodsmith said:


> Also you don't get something for nothing so if you look at the capacity of your pack you will need to find a genset that was able to put that much capacity back in without having to wait 8 hours for it. That would be a big genset. It would also need to use fuel so you have fuel weight to allow for. Then there is the emissions and noise from the genset reving its head off charging your pack.


An 8 or 9 kw genset can still extend range significantly. Additionally, it can run while parked on a longer trip. Example, some of my son's hockey games/tournaments are just outside of the PEV range, running the genset would make these trips possible. As far as emissions, ok...but LPG on the Kohler is one of the best for small ICE's. You can run them inside building with people present for example. RPM's can be throttled for certain locations also.


Woodsmith said:


> Given all that, if you needed that sort of range extension then you may as well buy a good factory design hybrid or even a very efficient ICE car. Mine gives me 60-65mpg on diesel.


Finally, in my case, this genset is a welder (i'm a journeyman welder) so, that makes it dual purpose, and finally it would be backup power for house in case of power outage.....which makes it triple use. 

The single biggest deterent for people buy/wanting PEV is range. 40 km may be all you need for 90% of the time...but that other 10% is something that can not be tollerated by most. This helps to bridge that gap I believe.

But hey, it's a free country...so ppl can buy what they want and do it any way that suits them.


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## Woodsmith (Jun 5, 2008)

If you have to carry the genset welder anyway then why not. That makes it seem like a sensible proposition.

I'm a furniture maker and teacher. My journeys are split in to taking myself to college with just a bag of books or towing a 1.5ton trailer about behind my car with either timber or furniture in.
The college commute is 70miles round trip at 60-70mph and the furniture can be anything from local to 250miles.
Like you it has to be a case of what does work in reality I guess. The UK EV people suggested to me that my lifestyle wouldn't suit what I could afford in an EV.


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