"Petroleum Battery" engine drives wheels without mechanical transmission

The Robot Cantina Channel has a bunch of projects that could be adapted to all sort of projects for vehicles and small scale farm equipment. In their recent videos, they did some tests with an engine running an alternator, which then powered an electric golf cart. They posted an update indicating they made a mistake with the figures and actually got much better fuel mileage than they originally posted. This short video tells the story:



You can go back and see the build videos as well as previous experiments that led this far. It is pretty impressive that it isn't quite as inefficient as one might think to convert to electricity and back. I particularly like that by only tethering the engine by wires instead of a drivetrain, you can put the engine wherever it makes sense for stability and different configurations you don't normally see.

For instance, I'm thinking of a 6x6. Something that can reach those otherwise inaccessible areas or pull a structure on skids. You can tuck a larger engine down low in the center and run 3 larger alternators, with each set up as a separate system for each axle. If uptime is critical then you mostly need to stock a handful of items that could be swapped out in the field.

Or something more lightweight like a reverse trike. There are lots of designs less common in the US that are already well suited to carrying cargo, and there is potential to carry more with a trailer. Adding a standard ebike kit would allow for quieter usage without the engine running. It should be possible to get a trimmer motor, and a small alternator and power an ebike motor, perhaps even be able to use one motor and switch between power sources.

Or maybe you need something more along the lines of an oversized powered wheel barrow, or something that can tow equipment around. I really like the DIY aspect of people grabbing what they already have and seeing what they can make work. It could be used with a biodiesel engine or even powered with wood gas. You could modify the vehicle design so the gasifier isn't fighting for space since the engine can be mounted almost anywhere. The sky is the limit, and I'm sure we will see more updates with the project they currently have going.

Okay, I was momentarily confused -- I now see you were talking about substituting a mechanical gearing system and instead taking energy from a conventional fossil fuel engine and turning the wheels with alternators and electric motors.

It certainly is possible. There are energy losses in every conversion. It also adds a lot of heavy and expensive hardware. I wonder if there is a sweet spot where the benefits outweigh the costs. Thoughts?

Heavy equipment has been doing this since the 1950,s. RG LeTourbeau who has made some of the largest earth moving equipment in the history of the world put electric motors in the hub of each wheel and used diesel engines to power them.

I worked for years on the railroad and they have the same set up: engines that power electric motors direct to the driving wheels.

Dollies that move RVs around use batteries instead of gas engines and work well, as do electric forks trucks.

I’m not sure what is so novel here, but maybe I am missing something?

Most times on the smaller scale of things direct coupling a petro engine to hydraulic drive motors work best. My mini bulldozer and zero turn lawn mower have this with no mechanical transmission. For smaller stuff, because of the torque driven and flow control in terms of speed, this is a very efficient combination.

You have just reinvented hybrid-electric vehicles. The drive train runs from electric, and has a battery which can be charged by plugging in, or kept topped up by a smaller onboard generator. As you have observed the energy efficiency doesn't make it unviable, as the conversion of chemical energy to forward motion in a standard car is pretty poor to start with.

I'm unconvinced by the logic that it is going to be better than a pure electric vehicle as a small onboard generator is going to be less energy efficient than a larger grid-scale generator which are highly optimised for efficiency, or compared to any renewables like solar or wind.

40 miles per gallon , thats less than i used to get driving my 1200 cc ford anglia 105 E , which although basic ---had a roof , wind screen and wipers ---a heater ---seated 4 people comfortably ---and a boot for some luggage----now i did nt play golf ---so i cant recall that it could be used as a golf cart---but it did  go fairly well on the highway  and keep up with the flow---so i can not see the major advancement to this design

You would figure that I would learn my lesson about posting new topics, but brain damage got me again. My apologies.

I hope the following isn't hijacking the thread, but the idea of one electric drive motor per locomotion wheel is new to me.  I've only recently seen some of the newer EV cars/trucks that are starting to use this,......and now several here have mentioned it not really being that new.  This is encouraging to me as we are looking into replacing a gas UTV 4X4 with a possible newer electric unit.  It appears some operate more traditionally with a single motor operating through mechanical transmission to power the wheels, whereas a few are starting to use the one-motor-per-wheel approach.  Do those with knowledge of these systems feel that one approach is more desirable than the other?  I was leery of the one-motor-per-wheel approach as being to 'new' and untested, but apparently not so...? And what about efficiency of electrical power use between single motor + transmission vs. one motor per wheel?  Thanks!

This has been around forever...

I remember when electric vehicles came out there was this gasp at the creativity of using "regenerative braking", that is where the inertia of the vehicle is used to turn the electric motors back to generators to help recharge the batteries. I rolled my eyes because locomotives have had this since the 1950's. On the railroad we called it "Dynamic Braking". It is a bit different because locomotives don't charge battery banks, they turn the electric motors driving their wheels into generators and pass the electricity through big rectifiers which slows down the train without having to apply the air brakes. The resistor creates a lot of heat so a fan blows the heat away. It is seen at the top of a locomotive. Locomotives are VERY big but also VERY simple machines.

John Deere has been using motors in the hubs of their bigger tractors for 40 years or more. They chose not to call it "four wheel drive" by "four wheel assist" instead. They use hydraulic power to do it, but it enabled things like combines and tractors to get power to the steering wheels without driveshafts, universal joints or CV joints that all cost money compared to one hydraulic motor with hydraulic lines going to it. I did not think it was quite as good because there was some torque loss when you got into deep mud, but it was better than no power to the drive axel at all.

Today the technology is way better on motors in each individual wheel because of computers. Whereas before vehicles had to have mechanical limited slip differentials to get traction to the more tractive wheel, today sensors detect when a wheel is spinning and apply power to all wheels individually. This makes a huge difference in corners where the inside wheels are rotating at a different speed than the faster outside wheels. A computer is fast enough to control this giving you better traction and control. This is the biggest difference between four wheel drive and all wheel drive. And you can feel it in the car. My 2003 Honda CRV has mechanical four wheel drive, whereas my wifes 2017 Honda CRV has synchronous all wheel drive, and hers is much smoother. The latter car literally is giving her traction on all four wheels. And when it is too much, like when stuck in a snowbank, the computer knows to limit the torque so you get traction and not just spin the tires, often giving the tires power in limited bursts. If you need more power though, this can be manually overridden. Because of computers it can sense more, sense situations faster and react, giving the car and driver far more control.

By the way... when I say "when electric cars first came out"... I meant in my lifetime. I am well aware that electric cars were huge in to 1920's.

They were big because of one reason, they did not have to be hand cranked to start. When the electric starter was developed and reached a price point where they could be put on most cars affordably, the electric car was phased out.

Thank you, Steve, for this illuminating description of 4X4 and AWD via electric motors.  Very much assists my analysis of what to get down the road for a utility vehicle for our small farmstead.