Electric car idea.

[RobS]

I do recall something about buses with regen some time back. Seems like they had a flywheel that would spin up during braking. Again, a weight issue for an economy minded car.

Regen in an electric car is relatively simple as the car already has the wheel motor and batteries.

For me, the optimal solution is similar to your original idea. A small (probably not tiny though) engine powering a generator powering wheel motors with the addition of batteries to handle peak demands. I'm not positive, but I think this is the layout of the Toyota Prius.

 

[N80]

I'm pretty sure the gasoline engine in the Prius is also used to drive the drive wheels. Electric motor kicks in only when done accelerating. Could be wrong.

I'm also intrigued by jet aircraft APUs. I saw a show years ago showing an electric car that used one of these along with batteries. They are basically simple gas turbines with like 2 moving parts at most. I'd guess the primary drawbacks would be noise and tremendous heat output. In the show I saw, it also seems like the turbine spun up a horizontally mounted flywheel that would continue to spin and generate power when the car was cruising or parked.

 

[BigE_]

Seems like one could take an electric car which has limited range, and put in a small diesel generator, roughly $3K, and add a small fuel tank. Yes it adds weight to the car but it would allow the batteries to recharge while the person is at work for 8-10 hours. Maybe extend the range while driving? Or do electric cars require a huge O amount of power to charge up?

I've seen what looks like a modified golf cart around town. It has license plates, so it must be road legal. Its got a generator strapped into the back. The generator is one of those Honda inverter type, so it is probably fairly efficient.

 

[N80]

I've seen what looks like a modified golf cart around town. It has license plates, so it must be road legal. Its got a generator strapped into the back. The generator is one of those Honda inverter type, so it is probably fairly efficient.

That's the idea I'm talking about!

 

[RobS]

I'm pretty sure the gasoline engine in the Prius is also used to drive the drive wheels. Electric motor kicks in only when done accelerating. Could be wrong.

I'm also intrigued by jet aircraft APUs. I saw a show years ago showing an electric car that used one of these along with batteries. They are basically simple gas turbines with like 2 moving parts at most. I'd guess the primary drawbacks would be noise and tremendous heat output. In the show I saw, it also seems like the turbine spun up a horizontally mounted flywheel that would continue to spin and generate power when the car was cruising or parked.

One of the big downsides to a gas turbine is the speed at which they have to spin to operate. The high speed requires a lot of gearing to get to a more useful rpm and all that gearing adds inefficiencies (not to mention cost and weight).

Any heat engine (gas, diesel, turbine etc.) is inherently inefficient as a good amount of the energy potential of the fuel is lost to heat generation. This is where fuel cells and such have an advantage.

Ultimately, it takes a certain amount of energy to propel a vehicle and it's contents. That energy comes from some source and in the case of a vehicle, must be transportable. The more efficient the conversion of the energy source to propulsion the better, and the less energy loss to braking, aerodynamics, road friction etc. the better.

Side note, saw the famous turbine powered Indy car at the 500 museum over Christmas. Still an impressive machine, after all these years.

 

[Tig]

The energy storage piece of the puzzle may be solved by supercapacitors. Supercapacitor - Wikipedia, the free encyclopedia

 

[Wayne County Hose]

There are basically 2 things which keep this theory from happening. Cost and weight. I was a tech on computerized high end forklifts before opening my shop. The forklift industry has about mastered electric propulsion. With the AC motor technology, regenerative braking, and the motor controllers currently available, I could make an electric car that would out accelerate most gas cars. Problem is, batteries won't last. Install a generator, now we have a weight issue. I've made 8,000 lb.+ forklifts absolutely bake the drive tires.

If you make a generator powerful enough to not need a battery, it would suck up too much fuel. It would be counter productive as you would burn more fuel to generate the electricity than you would have just using the IC engine to propel the vehicle. Remember now, energy can be neither created or destroyed, only transferred. Everytime you transfer energy, there are power losses. Onboard generating would create heat and sound energy. Both result in power losses. Now if you add batteries as an energy reserve, weight is an issue. And, you have to recharge those batteries somehow, and energy isn't free.

These electric drive systems are also pretty expensive. The entire drive system of a forklift, dealer cost, is probably in excess of $4,000. Add a generator, batteries, and the rest of the car and it quickly becomes cost prohibitive. It wouldn't be able to compete with the current automobiles and wouldn't sell.

You may be thinking, "What about the hybrids currently in production?" Well, they are made very light and underpowered. Try putting their drivetrains in a mini-van. The automotive industry is light years behind in electric propulsion. The systems are out there, but with the costs, they never really worked much on them as they couldn't sell and make a profit.

 

[RobS]

Well put WCH. Just curious, can you comment on the weight and lifespan of forklift batteries, as a data point for our study here?

An interesing aside to the gas/diesel hybrid is the solar powered car. If you have ever seen one they are very light, thin, sleek and flimsy. They are remarkable in their capabilities, but only in full sun. There are college level competitions for solar cars and they basically shut down with cloud cover. The answer for everyday use? Batteries, engine or fuel cell. Each adds a lot of weight and we're back to the bane of efficient vehicles.

 

[texbaylea]

One of the big downsides to a gas turbine is the speed at which they have to spin to operate. The high speed requires a lot of gearing to get to a more useful rpm and all that gearing adds inefficiencies (not to mention cost and weight).

Any heat engine (gas, diesel, turbine etc.) is inherently inefficient as a good amount of the energy potential of the fuel is lost to heat generation. This is where fuel cells and such have an advantage.

Ultimately, it takes a certain amount of energy to propel a vehicle and it's contents. That energy comes from some source and in the case of a vehicle, must be transportable. The more efficient the conversion of the energy source to propulsion the better, and the less energy loss to braking, aerodynamics, road friction etc. the better.

Side note, saw the famous turbine powered Indy car at the 500 museum over Christmas. Still an impressive machine, after all these years.

Chrysler put a turbine powered car on the streets back in the 50s or early 60s. Cities were unhappy since the exhaust melted the asphalt paving. Also you did not want to walk close to the rear or you would get burn't feet

I saw one on the streets of Houston but only briefly. I do not know how they handled the transmission of power.

Vernon

 

[N80]

These electric drive systems are also pretty expensive.

I'm sure they are. I used to race RC nitro powered trucks. Brushless electric motors are just now breaking onto that scene and they can outperform the nitro powered trucks, but at a cost. A basic brushless for an RC monster truck can run over $300 with speed control. Larger ones run much higher.

But here's the thing. When gas hits $10 a gallon and there is a market for millions of these units, prices come down, just like anything else...... except gasoline of course.