I had this idea the other day that could be a brain fart - but would be a relatively easy way to make a hybrid electric pickup truck.
The nugget of inspiration came from a conversion method for big rig trucks ... Concept: Plug-In Hybrid Drive Retrofit for Heavy-Duty Trucks ... Their idea (near as I could tell) was to split the axles at the end of the big rig. There's two drive axles on a big rig, and after the conversion the front of those axles is still driven by the diesel engine while the rearmost axle is driven by an electric motor. Instant hybrid electric big rig. You wouldn't expect it to do a long haul down the highway with the electric, but maneuvering around a parking lot etc could be done on electric power.
My idea was to apply this in a way to a pickup truck. Some pickups have two axles but another way would be to add a second bed to the end of the pickup. The first bed would be the normal drive axle connecting to the gas engine. The second bed would be a second drive axle to which you have an electric motor. It would be a matter of doing some welding, and fortunately trucks usually have a ladder frame under the bed so if you welded those two frames together it should be secure.
Hm?
Oh, and for a different take on a similar idea ... Otmar has this Stretch project where he welded together two VW Vanagon's to make a long one with dual drive systems (gas and electric).
I agree, (I saw something similar on Dodge's abandoned "through-the-road" system) a while back I was thinking about what project would I most want to put together if money was no object.
I'm a fan of diesels, because they only use as much fuel as they need (incredibly lean at cruise/idle) and they can run on vegetable oil (free as waste from restaurants).
I considered a rear-drive car with electric hub motors on the front, or a front-engine front-drive with electric drive in the back.
Hub motors have been made in full-sized car wheels, but they're hard to get. Also, they turn at wheel RPM's, so they are only a mild assist at high volts. Also its hard to coordinate the torque steer with two separate front hub motors.
By choosing a front engine/front-wheel-drive vehicle with an AWD option (VW Golf, Honda Element, Toyota RAV) the shaft can be removed and an electric motor with a planetary drive put onto the stock AWD rear.
When the stock engine is running at 3,000 RPM in a roughly 1:1 top gear, the 4ish:1 rear differential will have the wheels turning at ~1300 RPM. Most (available) industrial motors seem to run best at 3,000ish RPM's too.
Tesla uses a two-speed planetary transmission (yes?) to improve low RPM system heat, motor size, and overall efficiency to also reduce battery amp-draw-heat.
The combination of the 4:1 stock differential and the two-speed planetary gear is in my opinion, a doable off-the shelf adaptation.
from the 3 candidates I like, the golf has a 4-cyl turbo-diesel option.
The controller and back seat full of Li-ions would reduce it to a 2-seat car, but also 80+ MPG average with veggie oil option, and very fast accelleration using the ICE/EV motor at the same time when starting/passing.
Can I borrow $200,000?...(I'll put your name on the side!)
Mr Sharkey has something like your extra bed/axle idea in VW Rabbit. However, his uses an electric car and a gas-powered trailer. Click on the link below to view a pic of his car.
http://www.mrsharkey.com/evgfx/push0.jpg
I've owned too many gasoline powered cars to count on all my fingers and toes. Time to go electric.
Here's a similar set-up. An electric conversion Porsche 944, with a VW rabbit front 1/3rd as a pusher-trailer.
http://www.jstraubel.com/EVpusher/EVpusher2.htm