I was just thinking the same kind of things yesterday. I was thinking about converting a Ford F150 Crew Cab, Eleventh generation (2004–08) or Twelfth generation (2009–14); they look very similar, I doubt most people can tell the difference between them. I have seen some sell in the classifieds for $1000 with a blown transfer case, transmission or engine.
This is a very unique situation because you are getting away from the older style looking trucks, Ford 1992-1996 generation and the 1997-2003 more rounded generation, which tend to sometimes be rusted out. Cops or as I like to call them PIGS are always on the hunt for "bums" who drive those "older" vehicles, yet they let the newer vehicles slide. I have been victim to it, the vehicle prejudice.
These era of half ton trucks tend to be in the 4500 lbs curb weight category.
Ford Ranger is a popular EV conversion, weighs in at 3600 lbs.
Suzuki size type SUV's 2400 lbs.
You do not want to go with a strictly 100% electric vehicle because you are limited in the range. You want to be able to use gas/diesel if necessary to dramatically extend your range, but use electric when you take off from a stop, or speed up.
I do not think gas prices are where they are at in North America for a good return on investment.
The average driver puts on 20,000 to 25,000 km a year (15,000 miles), which uses $3000 to $3500 per year in gas.
A DC or AC motor is $1500, controller is $1500, batteries will easily be another $1500+.
You would have to see the benefits of going 48V or 72V, 96V or 144V. The more voltage the faster you go, but using it for stop and go you dont need 144V speeds, which is related to the wind of the motor (kv). The more amperes the more torque. And remember if you go 48V you can drastically increase your batteries Amp-Hour, and thus increase its peak amp output (the more strings in parallel).
I think your best bet is to use a series wound DC motor, 48V - 144V
check out this website
http://www.electricmotorsport.com/
They got a 85HP series wound motor 26kW!!!! Series wound motors are used to get moving large loads.
Think about that, a F150 is V6 4.2L and 202HP, while a V8 4.6L is 248HP. Dont need horsepower anyways for acceleration, what we need is amps, and the torque is instant, not curved like ICE.
This is my thoughts, have a "hybrid" system. Where you use the regular ICE (Internal Combustion Engine) at cruising speeds. You might want to look into if gasoline or diesel get better fuel mileage at cruising speeds.
Gasoline/Diesel is consumed most when you stop & go so an additional boost of torque with the electric motor would reduce the gas consumption.
How to install, get a machine shop to custom make you a rear axle yoke that has an added chain ring on it. Chains have been used in transfer cases for a very long time. The most durable is of course geared, like the NP205, chain NP203. There is something called a twin-stick, NP203/205 used by offroaders.
http://www.fourwheeler.com/how-to/129-0710-11-best-transfer-cases/
You install the motor ontop of the transfer case, with the custom yoke, or motor ontop of the rear axle with a custom yoke. Those are solid and never move, while everything else is meant to articulate.
I just dont think its feasible with gas prices currently. But the sooner you do it, maybe the sooner its paid off.
But remember, what is the consumable parts?
Motor Brushes and Batteries.
So going with a motor lets say 50kW at 48V if they make one, is your best bet.
http://www.motenergy.com/me1002.html
http://ep.yimg.com/ty/cdn/yhst-129399866319704/ME1002data.pdf
http://ep.yimg.com/ty/cdn/yhst-129399866319704/SCAN0071.JPG
The ME1002 is a Series Wound DC motor perfect for lite truck and small car EV conversions. It is 10 inches in diameter, weighing 190 pounds. Continuous current of 200 amps, and 550 amps for 2 minutes. Voltages from 48 to 144 VDC. Efficiencies of up to 92%. Perfect for use with the Curtis 1231 Motor Control. The power is 26 KW (35 HP)continuous, and 63 KW (85 HP) peak. More powerful than the NetGain Warp 9 and ADC FB1-4001 motors.
Typical shipping cost in the Continental USA of $150 by LTL truck. Motor Weighs 190 pounds. Motor in the shipping crate is 203 Pounds. The motor is shipped on a pallet measuring 48 x 40 x 30, weighing 240 pounds.