Electric drive with an ICE generator or ICE drive with supplementary electric drive?

[Boostermoose]

Alright you have two identical vehicles. Say, two small size diesel cars.

Car A, Diesel-electric: Rig up an electric motor to the non-drive axle, extra batteries that can be plugged in, extra throttle pedal, wiring, etc. At low speeds the diesel ICE runs at low idle and thats it. This charges the batteries to run the electric motor which would move the vehicle. You keep the diesel in neutral during these times so you can still steer. At higher speeds you just use the normal ICE engine to move the vehicle, shutting off the electric motor. You would have two throttle pedals and would have to make the decisions of when to change between motors. Which is in contrast to a production hybrid where a computer does that.

Car B, Electric-diesel: Gut the ICE, do a basic EV conversion with extra batteries that can be plugged in and all. But, add a very small diesel motor somewhere to top up the batteries when needed. The electric motor would be doing all the work at all speeds.

So which would be more efficient?

[mechman600]

Depends on how much low speed driving you are doing (using energy from the wall) in car A and how much diesel battery charging you are doing in car B.

[Ryland]

Chances are that the all electric drive with the diesel pusher or diesel trailer generator is going to be your better option, unless you tend to drive long distances most of the time, then you'd want to keep the diesel engine in the car.
I would not however idle the diesel engine, I'd size the battery pack to give you the around town range you want and install electric power steering so the diesel engine is off when you have it in electric mode, then connect your pot box for your electric motor speed controller to your regular foot throttle and either a switch that cuts the main contactor when the engine is running or a manual switch on the dash, the manual option would allow you to use the electric drive to boost mileage on long trips by supplementing power to drive the car, at this point I'd add a trim knob on the dash so you could have a little electric boost or a lot, depending on how far you were driving, over time you'd figure out how much boost from the electric drive you wanted to add to say drive 50 miles or 100 miles with the goal of ending your trip with a near dead electric drive battery.
Other option of course and if you didn't do long cross country drives this would work great with the electric boost option, remove the alternator from the diesel engine all together, have all electronics run off the electric drive pack that gets plugged in, this will take load off the diesel and give you better fuel mileage, only thing is, if you have the electric boost option you need to size the battery pack for the longest drive you plan to make running lights and everything, not often an issue, but I'd have the low voltage cut out on the drive pack cut out the main contactor when you still have enough battery capacity left to run your lights for say 2 hours.

[Ryland]

A year or so ago I started a thread describing in greater detail a plug in hybrid of this sort, only using a Ford Ranger pickup truck, because if you get a 4 wheel drive version and remove the transfer case, connect the transmission to the rear wheels with the drive shaft from a 2 wheel drive truck and replace the transfer case with an electric motor you end up with electric front wheel drive, gas rear wheel drive and enough space behind the drivers seat of the extended cab truck to have 12 golf cart batteries all sitting below the window with enough space to water them and for a plexi glass enclosure to keep the driver separated from them, lithium batteries would of course be a better option but I was looking at doing it cheap with stuff anyone could get easily.

[Boostermoose]

Thanks for the input. The AWD hybrid ranger sounds great, did you complete that project? If I could find a light duty AWD drive diesel truck or suv then it would be perfect.

[GreenHornet]

Originally Posted by Boostermoose

Alright you have two identical vehicles. Say, two small size diesel cars.

Car A, Diesel-electric: Rig up an electric motor to the non-drive axle, extra batteries that can be plugged in, extra throttle pedal, wiring, etc. At low speeds the diesel ICE runs at low idle and thats it. This charges the batteries to run the electric motor which would move the vehicle. You keep the diesel in neutral during these times so you can still steer. At higher speeds you just use the normal ICE engine to move the vehicle, shutting off the electric motor. You would have two throttle pedals and would have to make the decisions of when to change between motors. Which is in contrast to a production hybrid where a computer does that.

Car B, Electric-diesel: Gut the ICE, do a basic EV conversion with extra batteries that can be plugged in and all. But, add a very small diesel motor somewhere to top up the batteries when needed. The electric motor would be doing all the work at all speeds.

So which would be more efficient?

There is so much that plays into this that it really makes it difficult to do a comparison to be honest. Either set up works and each setup has current vehicles taking advantages of these setups.

Your pure EV individual will not be in favor of this at all as they will argue it is not as efficient as an all electric conversion. Which is true however batteries currently on the market do not have anywhere close to the energy storage of diesel or gas for that matter. They also cost more up front which is a big hurdle for most individuals.

This is why there are hybrids and why there will be more hybrids in the near future.

If engineered properly you can have a successful hybrid that is very economical and has solid performance at freeway speeds. The problem is there are to many options and most people do not get it right and end up over engineering and spending.

If you are trying to get an idea as to which route you should go then I would be more in favor of the series route using a small diesel/generator and having an electric traction motor to propel the vehicle. I kicked this around for years as to which approach would be best for my project. I think the ultimate way to go would be to use a power split device so you could have the best of both worlds. This allows you to have a series/parallel hybrid and gain the benefits of both. Maybe someday I will build this setup but right now I have settled on the series route as it offers some advantages for my project I would not get with the parallel configuration. Of course this all might change a month from now LOL :-) but right now the series for me is looking like the best option.

Take care,

GreenHornet