For a while, I’ve had an idea rattling around in my head….
A couple years back, I picked up an old Mercedes 240D as a parts car, to use the engine to convert my pickup truck to diesel. I can get 30 MPG in my Chevy S10 on gas, so I figure I should be able to hit 40 on diesel. More recently, I’ve kept helping out friends on their electric car projects, and for a while there even ran my Electric Geo Metro as a propane hybrid.
This summer, I was amazed to have been invited to Vienna, Austria to be a participant in a brainstorming/think-tank to help design the car of the future.
Somehow, I’ve managed to stumble my way through the school of hard-knocks in clean transportation design.
When two of my friends started converting pickup trucks to electric with large forklift motors we pulled out of a junk yard a couple years ago, it gave me and idea. The DIY Plug-In Hybrid Pickup Truck.
Where I live, everything is either really close by, or an 80 mile round trip. I’d actually be a good candidate for a Chevy Volt, except that I actually do use a pickup to tow a trailer, haul firewood, transport motorcycles, and do the things that trucks do. Now I don’t want the Volt to take this personally, but it’s also a bit out of my price-range, and still runs on gasoline. (They are nice cars though, if you are in the market, take one for a test drive.)
If I built my own hybrid, I could design it the way that I want – my choice of fuel, engine, and motor.
Once I had that concept in my head, I really couldn’t shake it out of there. I’ve come up with a couple ideas, including using a 4×4 Geo Tracker or a classic VW Rabbit Pickup Truck. Both of which would have some limitations. Finally, I’ve settled on a Mercedes diesel engine, a forklift motor, and a two-wheel drive truck. Here’s why.
1) I already have most of that stuff! People sometimes talk about “ideal” ways of designing something, using very particular parts, but the costs add up. By mostly making do with what I have, I can afford to make the project happen.
2) DC Series-wound forklift motors have already proven themselves to me. The Electro-Metro runs great on a $50 forklift motor. A couple of friends are driving EV trucks with forklift motors, and I’ve always been impressed by the hotrod motors that Jim Husted makes from stock ones. While a series-wound DC motor is not usually that good for regen, it IS possible to do it. More importantly, a series-wound motor has the TORQUE to spin the differential directly. Also, forklift drive motors typically have a driveshaft and a tailshaft. By shortening the drive-shaft and inserting the motor there, I’ll be able to to connect the transmission output to the motor. In effect, the motor itself becomes the “power-split device” required to connect two power sources to one set of wheels. (Think of it as a really low-tech planetary transmission!)
3) The diesel engine is pretty obvious. Not only do diesels get better fuel economy than gasoline, but you can also run them on bio-diesel or waste vegetable oil. The Mercedes 240D was very popular for veggie oil conversions.
So, the over-all concept is to be able to drive the truck on just the electric at low and medium speeds, around town, and general use. With the manual transmission in neutral, the engine is no longer connected to the motor, and doesn’t even need to be on. When I want to go on the freeway, or need additional power (towing, etc) I can turn on the diesel engine. The engine goes through the transmission, spins the motor (unpowered) which spins the driveshaft, and the car goes down the road.
What I showed in the video is a basic overview of the driveline. Of course the big trick is going to be all the details. The mechanicals of hooking everything together will be a fair amount of work. After that, it’s just a matter of dropping it in the truck. Then it’s on to modifying an Open Revolt motor controller to make it work in a plug-in hybrid instead of just an electric car.
I know this project is going to take a while, but it will be exciting, and with a little positive input from my friends, we’ll build something great.
A few questions already from YouTube:
Q) Not an AC motor?
A) No, I haven’t seen any that meet the magic ingredients of having a tail-shaft, enough torque for direct-drive, and are affordable.
Q) What system voltage?
A) As high as I can afford – aiming for 144V, but that also means changing the timing, so I wouldn’t be able to have reverse gear in electric (as timing would then be retarded.)
Q) Where would the batteries go? Going for Used batteries again?
A) The batteries would go under the bed of the truck, similar to most EV pickup conversions, but I’ll have to work around the exhaust system and fuel tank. I might put a smaller fuel tank in there to make more room. I’ll have NEW batteries in the truck this time, lithium if I can get some sort of sponsorship, otherwise just new lead-acid will give me proof that everything works the way it should.
Q) How about having the diesel engine run a generator, make it a series-hybrid?
A) I already experimented with the Electro-Metro as a series hybrid when I added the LP generator to it. My making the truck a PARALLEL hybrid, EITHER system can push the truck down the road. If I ever have trouble with either system, I can drive home on the other. As a parallel hybrid, I’d also be able to get a power-boost by using both systems at once – think of having an electric turbo-charger on a diesel engine!
Q) What are the “weird details”?
A) It’s things like the accelerator. Since I have two different drive systems connected to each other, do I need two separate pedals?!?!? I don’t know, but figuring it out will be half the fun. Also, in one of the photos below, I mocked-up where the driver and passenger seats will go. In the truck, it’s got a bench seat. I might have to convert to bucket seats just to cut a hole in the cab to make the motor fit!