[madderscience]

go for a fully enclosed frame AC motor if you can. That way the motor won't get full of sand/dirt/mud. The 144V HPEVs AC system would provide plenty of power for a lightweight dune buggy when mated to a VW transaxle, but I think it is an open frame AC motor. No brushes, but still not ideal given the use case. Perhaps forced air cooling and filtration would be enough depending on how you want to use it. Another option would be to try and reuse the complete transaxle out of a production EV like the leaf, but you will need to either modify the inverter (replacing logic boards) or replicate the necessary CAN bus signals needed to make it work. Lots of people are working on both these angles for common OEM evs so monitor relevant threads.

Battery size would be very dependent on your use case. bombing around in the sand is going to use a lot more wh/mile then cruising on the street so the best way to estimate run time might be to compare gallons/hr energy burn how you like to drive and convert that to likely electric power endurance. For example if a dune buggy burns 4 gallons/hr of gasoline that is equivalent to 125kwh of energy. However off road where you are constantly varying throttle and not cruising steadily it is likely that the electric drive train would be 4 or 5 times (if not more) more efficient, meaning you would need a battery with usable capacity of 25-30kwh to get the same run time assuming same weight, conditions, driving style. The 2016+ nissan leaf at least in USA has a 30kwh / 24kwh usable battery. The 2018+ leaf will have a ~60kwh pack.

It is likely the dune buggy will gain signficant weight over its gas counterpart owing to the battery pack weight (there isn't much weight to take off in an air cooled buggy during the conversion except the engine and gas tank) so factor that into your calculations.

Good luck.

 

[alanhalley]

Use cases for a buggy:
1. Driving less than an hour to lunch on Sundays
2. Driving on the beach after lunch for an hour
3. Occasionally take it to the dunes for fun

The Super Buggy weighs 820 kg with a 100 hp VW Golf 1.6 liter water-cooled engine. It does zero to 60 mph in 10 seconds, which is adequate. A bit more power might be nice for climbing sand dunes.

It looks like the Leaf drivetrain might be suitable, but after watching the video of a Leaf running on a bench with the maze of wires, I’m wondering what I need to control the motor in a buggy with no power steering, no A/C, no navigation, etc.

Or can I buy something similar to the Bosch eAxle today that would be easier to drop into a buggy?

 

[brian_]

The Super Buggy weighs 820 kg with a 100 hp VW Golf 1.6 liter water-cooled engine. It does zero to 60 mph in 10 seconds, which is adequate. A bit more power might be nice for climbing sand dunes.

I think expecting comparable or better performance than the Golf drivetrain with the drivetrain of a commercially-produced EV such as a Leaf would be reasonable... at relatively low speeds (true for the dunes), and if the vehicle is the same weight. Unfortunately, I would guess that the electric version would be heavier.

 

[brian_]

Or can I buy something similar to the Bosch eAxle today that would be easier to drop into a buggy?

When a component supplier such as Bosch announces a product at an industry show and says it is "available", they usually mean that an auto manufacturer can negotiate a deal to buy tens of thousands of them, after spending a hundreds to thousands of engineering hours to determine the right specification and redesign the vehicle to accommodate the system. Bosch isn't offering these for sale to individuals... which is why people who want state-of-the-art electric drive systems salvage them from wrecked production EVs.

The situation is a little bit like conventional car engines. It isn't practical to buy most of them for installation in anything other than a car that it normally comes in, because the control systems are integrated with the car. Some engines are offered by some manufacturers as "crate engines", set up to be installed in other vehicles (usually for racing, or upgrade of old cars not subject to current regulations). I haven't heard of "crate drive units", such as a Leaf system-in-a-box from Nissan, or a Bosch eAxle direct from Bosch or from any auto manufacturer using it.

 

[alanhalley]

I think expecting comparable or better performance than the Golf drivetrain with the drivetrain of a commercially-produced EV such as a Leaf would be reasonable... at relatively low speeds (true for the dunes), and if the vehicle is the same weight. Unfortunately, I would guess that the electric version would be heavier.

The batteries will increase the weight of the buggy, but I think that the torque from an electric motor will make the buggy more responsive at low speeds, which may make it feel "faster". Fast is relative, of course. Where I live I have to drive 30 minutes or more to get to a stretch of road that has a speed limit above 60 km/hr.

 

[alanhalley]

...which is why people who want state-of-the-art electric drive systems salvage them from wrecked production EVs.

So I can buy a drivetrain (motor, inverter, charger and gearbox) from a wrecked EV and then I need a motor controller. Where can I get a motor controller?

Or I could buy a new motor, inverter, gearbox and controller.

New components cost more than used parts, but probably require less tinkering to get everything working, I would guess.

 

[brian_]

So I can buy a drivetrain (motor, inverter, charger and gearbox) from a wrecked EV and then I need a motor controller. Where can I get a motor controller?

Other members of this forum who have done this often use the controller as well... as much as everything electronic from the accelerator pedal to the motor.

Others who have done this sort of thing can provide a much better idea of the complexities of these choices.

Or I could buy a new motor, inverter, gearbox and controller.

New components cost more than used parts, but probably require less tinkering to get everything working, I would guess.

As long as the salvaged parts are not damaged, I don't think new parts would change the tinkering level at all. If the new parts are for a production vehicle, they will not come with any information to assist with non-standard use; they are sold to be swapped directly in place of failed parts. Figuring out how they work together well enough to make them work in a different vehicle is not easy, used or not.

New parts intended for people building their own vehicles should come with more information and simpler interfaces, but cost is definitely a concern, and the number of people in this forum taking the do-it-yourself route is evidence of that.

I think most people would find the cost of new parts from a production vehicle to be wildly excessive. With the cost premium of parts compared to new vehicles (buying an entire vehicle part-by-part would cost far more than just buying the vehicle), and with subsidies in some areas for purchase of an EV, it might be cheaper to buy a new EV and throw away everything other than the desired electric drive parts than to buy just the parts. I'm not suggesting that anyone do that, of course, but that's the economic reality.

 

[alanhalley]

it might be cheaper to buy a new EV and throw away everything other than the desired electric drive parts than to buy just the parts.

Yes it probably would be cheaper.

Michael Bream at EV West said that his customers typically spend $17k on parts to convert a VW. That's almost the price of a new Super Buggy. So I could spend something like $35k on an electric buggy with new motor, inverter, charger and batteries. I'll look more closely at using used parts.