I know I am just an old mechanical designer who knows close to nothing about electricity but why can't an electric vehicle charge itself? Gen sets can charge batteries, which most are just diesel engines turning a generator that produces electricity, seems as simple to me as hooking a generator to the rotating mass that the electric motors run? Is it that there is just no profit in it? Discuss...

Because it takes power to make power. Use power to keep the batteries charged and you don't have any left to power the car.

this is inaccurate in regards to a hybrid. They have enough power to charge the batteries and keep the car running down the highway. Speed limit is 75 around here and that Escape had no issue doing it.

https://en.wikipedia.org/wiki/Ford_Escape#Hybrid

If you are referring to a pure electric vehicle, then the best way to keep those batteries charged is to not drive it.

When electric motors and generators were invented/discovered, many people thought it would result in a perpetual motion machine. It doesn't work that way. if you're using an electric motor to run a generator, you lose power due to the resistance of the wiring and connections, without even trying to draw power off to do anything extra like power a vehicle.

When I ran the municipal garage, I was trying to get a test program going with my city, Mack, and Parker hydraulics for Hydraulic Launch Assist for refuse trucks. Residential refuse trucks have a crazy duty cycle: from a dead stop, accelerate at WOT for about 70', then stand on the brakes for 50' to get to the next bin. if you install a hydraulic pump/motor in the driveline and use it as a pump to charge an accumulator during braking to store the energy (fluid under pressure), then release that energy to drive the motor during acceleration, you theoretically can use a smaller engine to power the truck, use less fuel, etc. Sounds great, right? There's a similar system for city busses, but the duty cycle on refuse trucks means by pressurizing the fluid you increase it's temperature as well, and when you do it 500 times a day, your fluid overheats in about 100 stops. You end up with a HUGE reservoir and cooler for the fluid, to prevent that, and the weight of all of that equipment and fluid eats up any benefit of the system.

The bottom line is that gasoline and diesel fuel became the common motor vehicle fuels through a Darwinian process that began in the late 1800's. They are (relatively) stable, can be stored at common atmospheric temperatures and pressures (in quantities from small to huge), allow for refueling with VERY minimal training and no protective equipment, and became available essentially worldwide. EVERY alternative has significant drawbacks in at least one of those areas. You can argue that gasoline is a fire hazard, but it's (again relatively) easy to extinguish. Look at the reports on the wrecked Tesla that took over 4 hours to drown (literally) after it sat untouched in a junkyard. Forget your gloves when refusing your propane vehicle and you can lose a hand to frostbite (imagine letting your 16-year-old kid try it on their own). CNG vehicles require complete purging of the pressure tank before any maintenance work is done, OR a completely explosion-free shop be constructed with enclosed electrical systems, no spark-producing tools, etc. Hydrogen shows the most promise but again the technology is not yet mature enough for mass production.

IN MY OPINION, the move away from fossil fuels is another example of politicians trying to legislate technology. They want what they want (and WHY is a different discussion) without concern that it's not practical in today's world.

I know I am just an old mechanical designer who knows close to nothing about electricity but why can't an electric vehicle charge itself?

Some automakers plan to put on board generators as "range extenders" to burn gas to recharge the batteries.

"Some automakers, including BMW, are producing electric vehicles with internal combustion “range extenders.” These are essentially efficient generators that can burn gasoline to replenish the battery while on the road. Ram may be eyeing a similar setup for future vehicles."


https://www.motorbiscuit.com/heres-everything-we-know-about-the-electric-ram-pickup-truck/

I look forward to future "range extender" jokes...

I would have thought that would have been in Engineering 101 !!! You can't get more energy out than you put in. HOWEVER, consider that electric motors are also generators. While the motor is used to propel the vehicle, it can generate power when used as a brake or when coasting down a hill. So, if you were going for a long drive and it was all downhill, the vehicle could charge itself. However it would not generate sufficient enegy to make the full uphill return trip

Electricity is a funny demon. But like the old saying goes: "There's no such thing as a free lunch." Power (or "energy") is ALWAYS lost through friction, heat, resistance, etc.
You'll never get MORE out of what you put in.

A fun experiment is to get a cheapy little 40-amp alternator. Hook it up to a battery source and a regulator and now YOU try to turn that alternator. You might be able to; but not sustainably enough to be useful.
Now, get a 200-amp alternator from a big truck and do the same thing. A small team of dogs wouldn't be able to turn it. You would need the mass of something; like a car - to be able to turn that sucker.

Lots of the electric things have regenerative braking - and this is a wonderful thing. But you can't have it ON all the time - the drag would be immense and you'd be wasting 10x more energy trying to get something out of it.

Why don't race cars have alternators? It's not because they don't have headlights! It's because that little chargin' whirler saps up an easy 5hp. The bigger the alternator, the more hp it takes away!


Personally, I think we should be looking more into Hybrid/Turbine technology. A small Turbine powerplant that has three states: OFF, idle or RUN and therefore can be tuned to run as cleanly as possible. It's only job is to turn a generator that can power an electric motor and maybe a small, backup battery. A multi-fuel Turbine would not only be able to run off of ANY combustible fuel, it can be tuned to run as cleanly or cleaner than any current internal combustion engine; but it's maintenance now drops to ZERO and moving parts/failure rate plummets. Win-Win for the consumer; not so much for the manufacturer.

But I also think we've gotten away from simple reliability. I firmly believe ALL electric cars should have a simple, planetary transmission. Why? Very Simple. A "classic" three-speed or even 2-speed transmission would:

Provide a "PARKing" position that everybody and their dog is used to.
A much simpler reverse function - rather than reversing the electric motor (which requires big, heavy circuit breakers and relays) - just do it hydraulically.
A NEUTRAL position for pushing/towing that not all electrics have!!
Drive for every day driving.
Gear reduction should such an idea be necessary.

But, the other great thing about a simple transmission would be it's fluid pump. I don't think it would be much parasitic loss to have that same pump power a hydraulic power steering unit and a hydroboost brake unit. We could also plumb a heater matrix into the fluid system because the fluid will get warm. Why not dissipate that heat through the cabin rather than have 39 separate electric systems doing all these jobs.

I really think the designers of today believe themselves to be much smarter than they actually are. None of them have ever heard of the phrase "Putting the cart before the horse." They've no idea what a cart nor a horse is.