battery car + towable generator = ??

Tell me if this is madness or genius...

Picture owning something like an i-Mev or Leaf. It's a great second car, but you can never take a road trip in one.

Now put a trailer hitch on one of those cars. Add your typical HF small trailer, with one of these generators on it. Maybe not out of the box, but modified specifically to act as a battery charger.

Add the capability to remote-start the generator from within the car while moving. Better yet, add remote start to the computerized function of the car's "brain", so when the battery gets down to, say, 20%, the gennie fires automatically.

So... am I brilliant, or insane?

Didn't the original Tesla have a similar setup?

why get a trailer when it will fit on one of those racks that slide into a receiver hitch? build a little bit of aerodynamic body work out of fiberglass to negate the aero penalty, and there you go.. of course you'd have to keep track of your fuel usage to see what kind of fuel mileage you are getting, and would the generator be powerful enough to charge the battery while the car is draining it?

Thats pretty much what the chevy volt does, so yes, the idea seems to work.

Well, that's a 5kw generator, which is at least what a home 240VAC charger would use, so I think it could charge pretty well on the fly.

isn't that called "what production hybrids do already," but without the hassle of towing a trailer everywhere?

on the other hand, towing a trailer with a generator on it behind a Leaf is an EXCELLENT way to make a normal Leaf move up one spot from the "ugliest car on the planet" position it currently occupies.

true, Irish, but I don't know of any production hybrids that:

a] use diesel gensets - which are way more efficient at a single RPM that any gas engine can be

b] use the liquid fuel engine solely to run a battery charger.

We have hundreds of them. A 5.9 cummins spins a generator and an enectric motor pushes the bus.

Wally wrote: We have hundreds of them. A 5.9 cummins spins a generator and an enectric motor pushes the bus.

sweet. now I want one of those in 1/8 scale :)

they have them for boats too.

EvanR wrote: a] use diesel gensets - which are way more efficient at a single RPM that any gas engine can be

Two things, diesels don't like to be started and shut down often to run based on battery state, which is how the Volt gas engine runs. The engine in the Volt for eample, runs at different RPM depending on load. In a genset, no, you run at one rpm, and don't shut down and turn back on regularly. In the variable load realm of a car, you do.

Secondly, if you are running on the genset, you are only using the HP of the genset to move the car. You can't produce more power than you're using to say, climb hills. Trust me, if you could ue a little genset runig at a constant rpm to move a car, the GM engineers would have done it in theVolt. There was a LOT of study on this, and the power the engine puts out is it. Otherwise your getting more energy out of the system than you are putting in.

Notice that in those buses, the diesel engines are pretty big. They have to be in order to provide the power necessary to move the bus, even though they are JUST charging the batteries.

b] use the liquid fuel engine solely to run a battery charger.

In fact, the Volt does just that, with the exception of two situations: Running up a mountain, and running 100+ mph, the engine kicks in to assist the electric drive motor. At ALL other times, if the engine runs, it's only to keep the batteries charged or the battery temp regulated.

Diesel trains have been doing this for years. Put the the generator in the trunk with ample sized intake and exhaust piped outside. Add some 'room' air to keep it cool and get rid of any extra fumes. Then seal up the cabin from the boot. You can even find controllers to start and stop it depending on the batteries' conditions.

In reply to RossD:

But again, you're not going to get more hp out of the system from the batteries than you're putting in to start with. Which means that at any given time, if you're charging the batteries while driving, you're only using the hp of the generator to move the car. How many small gensets do you know of that put out enough hp to move a car effectively? At idle?

Agreed on the total power.

But with the batteries storing energy, you should able to get a higher peak when needed, with less being available afterwards. (Does that seem right?...)

In college, I calculated something like 12 hp to propel a Ford Contour 35mph or a flat road.

RossD wrote: But with the batteries storing energy, you should able to get a higher peak when needed, with less being available afterwards. (Does that seem right?...)

If you're running the generator to recharge the batteries, they aren't storing any extra power. This was the problem the Volt engineers ran across, and why the Volt works the way it does in "hold" mode. AND why it runs a high compression gasoline engine as the "generator."

Chris_V wrote: Notice that in those buses, the diesel engines are pretty big. They have to be in order to provide the power necessary to move the bus, even though they are JUST charging the batteries.

I would think that a bus is probably the smallest vehicle where this system is practical. Like you say even though it's half the size of the standard engine it is still big and runs all the time powering the hydraulic, air and A/C systems in addition to running the generator. The Volt type system is probably as close as you could get in a car.

Like this local guy did with his Metro? http://www.thedailypage.com/isthmus/article.php?article=33188

In reply to Chris_V:

At our cabin, we have 260 watts of solar panels charging (4) 6 volt batteries in 12 volt configuration. We have a 5000 watt inverter. We've had more than 260 watts worth of electrical load at one time. The electric toaster is something like 1000 watts by itself.

Could we sustain this amount of load? No. But you can get more out of of the system at peak load but you will have less power afterwards until your charging system to bring it back up to it's maximum potential.

Can't believe I'm first with this!

Yes it's been done:

https://en.wikipedia.org/wiki/AC_Propulsion_TZero

There were originally plans to make something like this for the Tesla Roadster too.

irish44j wrote: isn't that called "what production hybrids do already," but without the hassle of towing a trailer everywhere?

Sure if you planned on doing it all the time making it into a pseudo-hybrid.

Now if you only need the range once or twice a year... then... rent something else.

5kw isn't going to get you but about 6 hp out of a electric motor. If your car is using more than that at cruising speed, you are fighting a loosing battle. It's doable, but it might need a larger generator.

The Volt is one of a very small number of GM cars that interests me. I thought the price was silly when they were new, otherwise I would've really considered holding my nose and buying one. A Leaf is useless for me in my current situation, but a Volt would save me a lot of gas money.

T.J. wrote: The Volt is one of a very small number of GM cars that interests me. I thought the price was silly when they were new, otherwise I would've really considered holding my nose and buying one. A Leaf is useless for me in my current situation, but a Volt would save me a lot of gas money.

It's one of those cars that right now, make a lot of sense to lease. The tax credits come right off the top, so you're technically leasing a $30k car or less, and you only pay for about $12k of that during the course of the lease. You're not stuck with a high tech car out of warranty, and you can commute on 0 gasoline, while still being able to use gas to go longer distances if necessary or desired (like this last weekend when my wife went down to central VA to visit friends, a 400 mile round trip).

EvanR wrote: Tell me if this is madness or genius...

A bit of both....

You'll have to violate that pesky first law of thermodynamics. Any time you convert states of energy you lose a bunch.

Locomotives use diesel to run generators not because its the most efficient but because it is necessary. Using a diesel engine and a clutch to get a locomotive moving would generate so much heat that the reliability would be horrible. Since an electric motor makes peak torque at zero RPMs, its pretty much a requirement of train propulsion. Since batteries wouldn't be effective at storing enough energy, they need a way to chemically store large amounts of BTUs for long journeys. For that reason, they carry diesel which runs engines which generate electricity, which moves the train.

Let's say you need 30 hp to maintain cruise speed. If you want to generate 30 hp worth of electrical current, you'll need more than 30hp of engine to make it since electrical generation is only about 80% efficient. And, since the engine driving the generator is only about 30% efficient at converting chemical energy to kinetic energy at the crankshaft, you'll need three times the BTUs worth of fuel to generate the electricity required to maintain cruise speed.

Electrical energy to kinetic energy is one step. Its very efficient. Converting from chemical to kinetic, then to electrical, then back to kinetic is highly inefficient. You'd be WAY ahead just buying a fuel-operated vehicle.

Top Gear already did it.