Electric Truck with std. drivetrain?

[nickw]

Always thought this would be an interesting "Hybrid" solution. Std axles, std. manual or auto trans throw out the ICE and slap a EV motor up to the input shaft of the trans, which may end up being motor + planetary reduction unit to get it to work with the ICE drivetrain. Adds complexity for sure, at least relative to the std. motor + planetary gearing at each wheel, but seems like it may be easier to retrofit or re-engineer current platforms vs going fully proprietary vehicle ground up route. It would likely make packaging of the battery's difficult with drivelines and transmission interference....but we've solved more complex problems.

Based on the Porsche design, they are currently using a (2) spd transmission to make the most out of the EV drivetrain. Makes complete sense given the limitation of having only one power curve to work with....obviously EV's can get away with it since they can run a 0 RPM and have a wide RPM band to work with, but still have limitations.

I started thinking through this when I was discussing the Alta motorcycles with a buddy. I'm of the firm opinion that having a clutch and the option of selectable gearing (may be limited to 2 or 3), particularly on a offroad motorcycle, is vital for control. Alta couldn't take this route due to packaging and weight limitations, but for a 4 wheeled vehicle, seems like this could be worked around.

Any thoughts?

 

[Lovetheworld]

Yes, this is what people do when retrofitting.
Usually just an electric motor bolted to the gearbox. So you need to mate that. And there is usually a gear in there that does nicely with RPM band of the electric motor.

Downsides are that you will still have all the drivetrain losses, which are quite big. And since propelling a 4x4 costs a lot of energy and therefore needs a lot of batteries, it is important.
I also thought about it for our 4x4 campervan but it would need so many batteries.
Nice that you have all the gear options, including low-gearing, but that is hardly needed as you have plenty of torque all the time.

The Porsche design idea is nice, but in reality that car doesn't have any higher top speed, nor does it have a greater efficiency.
However, looking at EV conversions rather than expensive cars, you can see that people usually find a 2nd or 3rd gear doing nicely.

An alternative is to go with wheel hub motors.
With motors at each wheel it has serious advantages in 4x4. And you could dump the drivetrain.
That weight reduction of dropping engine + drivetrain is welcome since you need to place batteries.
However, wheel hub motors are usually limited in power and top speed. So when heaving a big 4x4, I doubt it is going to be useful.

 

[luthj]

A traditional 4x4 drivetrain doesn't take full advantage of the electric systems advantages. That is, having a motor front/rear, so no driveshafts to deal with (more room for batteries and a nice flat belly pan).

As mentioned all those seals, bearings, U joints, etc, are system losses (heat generators) as well as breakage/wear points.

But there is no reason you can't just fab a plate, and attach a electric motor to the transmission. It would need to be a manual trans, or you could possibly attache directly to the transfer case. It may require a gear reduction depending on the motor used. This was a common way to do EV conversions before production EV parts became available.

I think the cybertruck is a good example of what can be done with the motor/axle combo. Already lots of modders are using Tesla drive units (motor, axle, suspension, combo units) to convert vehicles. When the cybertruck starts coming into salvage yards for stripping, the entire drive unit can be removed and mounted to a donor vehicle. This gets you an adjustable air suspension, high output motor, and steering all in one.

 

[Lovetheworld]

That is great if that complete axle is easy to fit in your car, which is sometimes the case.
But more often it is not, and you have a working car, you just need the electric motor in there.
Then you just want the motor, which is already happening with Model S drive units as mentioned.
However, the Rivians could be nice too, as they have a motor per wheel, but not in the wheel. Could be more simple and more capable offroad.

 

[javajoe79]

With appropriate final drives I’d think a tesla drive could be used front and rear. They’re a pretty simple gear setup so maybe someone could make some alternate ratios that would work well with larger tires and more weight. I’ve talked about it with my electric Porsche customer and he’s considering a classic 4wd electric truck build next. 2 tesla drives in a 80s blazer or bronco maybe. Turn the drive units downward for more clearance and build 4 wheel independent suspension for it or use junkyard parts. Could be a really fun build so it’s exciting to think about doing.

 

[luthj]

With appropriate final drives I’d think a tesla drive could be used front and rear. They’re a pretty simple gear setup so maybe someone could make some alternate ratios that would work well with larger tires and more weight. I’ve talked about it with my electric Porsche customer and he’s considering a classic 4wd electric truck build next. 2 tesla drives in a 80s blazer or bronco maybe. Turn the drive units downward for more clearance and build 4 wheel independent suspension for it or use junkyard parts. Could be a really fun build so it’s exciting to think about doing.

Indeed, lots of good options for medium duty IFS out there. Custom CV axles, tesla drive motor/drive, maybe leaf batteries? Sounds like a good option.

 

[DaveInDenver]

What you're talking is the concept this company is doing. They call it a "crate electric V8" and it's essentially a motor built into a frame the size and shape of a small block Chevy to make it easier to mate and mount. There exists a lot of aftermarket for doing those swaps so transmission adapters and motor mounts are common.

As I understand it you'd probably pick 2nd or 3rd gear in a standard transmission and it would be about right. Seems like a lot of wasted space that could be batteries but the simplicity is clearly an advantage.

https://forum.ih8mud.com/threads/electric-tlc-fj-40-build.1040022/
https://electricgt.com

 

[gatorgrizz27]

I’ve wondered why the hybrid systems like Land Rover is coming out with in the new Defender don’t just mount an electric motor to the transfer case, like how some of the older ones had a PTO output. You’ve got the transmission going in the front center, front driveshaft coming off the front side, and rear driveshaft coming off the rear center or side, leaving space for another coupling.

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For running around town or on trails, it seems you could have the engine running to power the steering/AC, etc, but just idling. Put the transmission in neutral, and flip a switch to move the signal from the existing throttle position sensor on the pedal to control the electric motor.

If you end up needing more power, just bump it into drive, the engine is already running, and the throttle position switch could automatically flip back over to operating the throttle body.

It might even be possible to switch over smoothly while cruising on the highway if the electric motor had enough power to maintain your speed. Accelerate with the gas engine, let off the pedal, bump it into neutral and hit the switch, back into the pedal.

 

[Lovetheworld]

@gatorgrizz27 That would be a very rude solution from a car manufacturer when (for example Toyota/Lexus) have been building better systems for years.

I don't even understand why some car companies have been developing 48 volt mild hybrid systems. Or develop new hybrids without a plug. Yeah they can work nicelY (see 20 years of Prius) but just skip it when developing something new. It seems like a wasted effort.

Also, you really don't want all the drivetrain losses, so it would be great if you can skip that.
With full electric you certainly don't want the classical drivetrain, not only the losses but also the weight needs to be saved.