Electric Off-Road Vehicle - Why Not??

Leisure activities a do not think are in the best interest of a manufacture to create a product for with new technology. Little demand for the product as it is. As the consumer bulks change and question reliability.

That does not stop you from creating your own. Wish you luck! Let us know how it turns out.

I have done extensive research to convert my '72 Commando to full electric. The biggest problem I found is the space to cram the batteries, and the huge weight offset from doing so. You are correct in the torque issue, that was a huge draw for me...what interested me most.

Although...it sets up a whole new dynamic for rock crawling and driving in soft material. Most of the weight would be shifted to the back end. Plus, I would lose my "trunk" and I have no other place to put my "stuff".

The cost is the biggest factor for me, which would be about $4k using scraps and doing the work myself.

Cuba-Pete,

To your point's about weight and space, I suppose a fair amount of thought would need to be placed on which frame layout would work best. Ideally you would want to either place the bulk of the weight directly over the drive wheels or to spread it out evenly while keeping the CG as low as possible. I don't see the additional weight as much of an obstacle for rock crawling but it would come into play if your passion was running in the soup. Of course too light is a problem there too.

So yes, there would be several things to consider but if one could pull it off, I think the idea would take off. Imagine military vehicles using this technology. Afghan sand or jungle mud are no problem for sealed motors that have no gears to wear out.

Lastly, like everything (good) there is that pesky cost concern. However, if I knew how to build an electric off-road vehicle out of the scraps and spare parts you refer to, I'd not have any problem throwing $4k at it. Would there be anything patentable about it???

I think one of the obstacles to overcome would be how to secure the batteries. An off-road vehicle is subject to rough bumps, water, turn-overs, etc. The batteries would have to stay put under such conditions without cracking the cases or leaking acid. The average golf cart would not stand up to those conditions.

I have been looking into a vehicle for use carrying equipment in a large 8 story parking garage. I am being told that the hill climbing will eat up the power in the batteries of an electric vehicle. In other words, build a ICE powered vehicle that can do the ramps at the desired rate, and then build a fuel tank that will allow doing the ramps as many times as you want.

Rock climbing, and operating in sand and mud will also consume power, that will need to be replaced when it is used up. That will require carrying more battery capacity than would be required if operating on hard level pavement.

I have had thoughts about using electric motors but my thoughts were more to the idea of using the gas engine to turn a generator and electric motors mounted to the differential. My idea of the ultimate would be to have a motor on each wheel built and mounted so it would be inside of the wheel rim so that the axles could be eliminated.

My only problem is the brainpower and dollars to build such a setup.

Randy

Randyl - I think you have the right idea about generator-motor drive. To me batteries in a rock crawler offer serious center of gravity issues. In a drag racer you can put them low down around the drive wheels. Obviously impractical off road. Downright scary on a side slope.

How much power does a practical rock crawler (jeep size) need to have both to climb the rocks on the trail and get to their location at a reasonable speed? How much more speed reduction is needed to reach rock crawling speeds?

If you put electric motors in the wheels they would have to have many poles (read expensive to produce) or high gear reductions (also expensive) to get down to low speed and lots of torque. The only simple kinds of motor drive systems that come to my mind here are starters and flywheel ring gears. I seriously doubt that they would hold up to continued rock climbing duty.

Old VW bus/transporter rear hubs have a reduction gear in them. This hardware may deserve a look.

Ed Weldon

The gear reduction hubs were used in the Hummers also. Not the H2, and H3s, just the original ones. Also used in some off road construction equipment.

The gear reduction hubs were used in the Hummers also. Not the H2, and H3s, just the original ones. Also used in some off road construction equipment.

Sounds like you are OK in brainpower. Dollars are what keep many of us from achieving our dreams.

I'm smart enough to know I'd like a shiny new pickup. I'm poor enough to know I won't get it.

Don't give up.

Mitsubishi had a concept EVO with 4 electrical motor on wheel. Real All Wheel Drive.

http://www.instructables.com/id/Make-Your-Own-Miniature-Electric-Hub-Motor/

you might try the electric diy forum there are several people there doing thing's like you would like to do they are doing now. At least one old military jeep and several off road UTV'S of different sorts and also several different tractors with gear reduction drive system.And if memory serves me right there is at least one AMC eagle that has been electrified. leave it to a bunch of "ENGINEERS" to over complicate things. The old method of trial and error will work almost every time. And with electric you are correct you can get a lot more torque to work for you. And I believe the clip you saw was "Walyen" of the White Zombie fame and that vehicle is a Datsun B210. You have an option to use lithium batteries they are a lot less weight and a lot smaller than lead acid. They can also be made into packs of differing voltage and amp capacity. And how do I know this. As I am building a 1960 Falcon for drag racing electric style. I think any one trying to do something different is a step on into the future not just for greener ideas but just to be different. I also have a Thunder Bird Turbo Coupe I race with an alcoholic condition it wont run on anything but home made brew ethanol. So gas is not the only alternative to make a vehicle do what you want. So go have fun building your off road "electric" vehicle and enjoy no fumes and less noise with nature.

I'll say part of the problem is how long the battery will last.

I used to play with electric RC cars. They're much faster then their gas brothers but run time is only about 5 minutes. Those electric motors do have lots of torque but it also draws lots of current. A good motor speed controller is rated for over 400A. With this kind of current draw, you'll need lots of batteries.

I don't think it'll be fun if you ran out of power in middle or top of nowhere.

A can of gas is a lot easier to carry then a spare set of battery.

Maybe a really log extension cord

Really "log" cord?

I don't quite understand some of your comparisons. If an electric motor produces over 800 hp, and a substantial amount of torque (equal or superior to the fossil fueled dragster) it would perform nearly the same feat.

The difference is where the motor/engine produce their respective powers. Electric motors have a nearly instantaneous torque curve of maximum but a log curve for horsepower. Fossil fueled motors have complex h.p./torque curves which vary widely depending on the method of application.

A rock-crawling 4x4 would need a substantially different engine than a top-fuel dragster, but could have idential HP/torque numbers (at specific points along a curve). The curve would be totally different. This is the fundamental difference between old-school RV cams and high duration long-overlap bump-stick Saturday night cruisers who drag from light to light.

Rock crawlers don't spend all of their time at 10,000 rpm, and a dragster is useless at 4,000 and below.

I don't quite understand some of your comparisons. If an electric motor produces over 800 hp, and a substantial amount of torque (equal or superior to the fossil fueled dragster) it would perform nearly the same feat.

Right. We agree, pretty much. Actually the "substantial amount of torque" is not required, depending upon what you mean by substantial. Any amount of torque will do, if it is offset by high rpm -- only the product of the two counts. For example, the electric motor could produce its max HP at 50,000 rpm, with low torque. To get the speed appropriate for the wheels, (circa 1000 rpm part way down the strip) the torque would be multiplied by 50, and the speed would be reduced by 50 (by a 50:1 ratio in the transmission). So in the Datsun, it's not that the motor is producing magic amounts of torque, it's that the product of torque and rpm creates a large amount of HP. (Actually the shaft hp is probably more like 640: 80% of the 800 HP input.)

There is an analogy in lighting a room. Its not the voltage that is the determinant of brightness... it's not the current... it is the wattage -- the product of the two. Your twelve volt headlights are just as bright as your 120 volt room lights.

Part of your not understanding the comparisons probably has to do with the ranting nature of my post... they are probably not written clearly. The rant is answering a question not asked in this thread: There used to be (and still is, to an extent) an old hot rod debate re torque vs hp. The only determinant of acceleration is hp (if an appropriate transmission is used). A formula one car with low torque but high rpm produces loads of hp and accelerates like a rocket. The Kreidler out-speeds and out-accelerates the scooter. A 250 cc Yamaha road racer with 15 lb-ft of torque out accelerates 1200 cc Harley with 60 ft lb. (In real life terms, this means that the high-revving high hp [peaky] engines need more speeds -- the Kreidlers had 12 speeds, if I recall. With enough speeds -- or a CVT, all engines can become effectively constant HP devices -- for drag strip purposes, with pedal to the metal.)

The difference is where the motor/engine produce their respective powers. Electric motors have a nearly instantaneous torque curve of maximum but a log curve for horsepower.

In general I agree, although there are several different types of electric motor curves. The motors on my trike are permanent magnet, and as a result produce torque in direct proportion to current, and speed in proportion to voltage. So hp is a straight upwardly sloping line and torque is a straight horizontal line. AC induction motors are instead nearly constant HP devices, with very high torque at low speeds but falling torque at high speeds. The permanent magnet motor needs a multi-speed transmission, to produce adequate low speed hill climbing ability, without sacrificing top speed operation.

An AC induction motor is better than a permanent magnet motor for use with a single-speed transmission. However, as the Tesla demonstrates, such a configuration gives you near super car acceleration to 60, good 1/4 mile times for a street car, but a dismal (by sports car standards) top speed of 120 mph. Gear for the 160 mph that would be supported by the car's 250 hp, and then the 0-60 time suffers. So even the Tesla, with the electric motor type best suited to single speed transmission, really needs two or more speeds to keep up with a Porsche.

A rock-crawling 4x4 would...

I agree with all of this

In a modern train they use a high current-low voltage to produce the high torgue needed to get moving and then they change to a high voltage-low current to get the speed. (Torque then HP) This is done with diesel-electrics and modern electronics. After the diesel engine typically is an AC alternator, the power converted to DC, and inverted to 3 phase AC to drive the traction wheels.

You could make the same comparisons for every diesel-electric or nuclear powered Naval vessel. Those combinations are used due to the quick response necessary for high-speed maneuvers, along with huge gains in efficiency.

Instant torque available by using electric motors is very useful for this.

The modern diesel-electric locomotives don't use transmissions to start moving. They use the high torque produced by using the high current- low voltage. As I understand it, at 0 RPM you can have all the torque in the world but you have no hosepower and therefore you aren't going to go anyplace. As the locomotive builds speed he needs power but now his power comes from less torque but more RPM which ends up giving him the power he needs to travel at the speed he needs. So to do that they switch to a high voltage-low current. Now that I've said all that read the link below. The author does an excellent job of explaining it all.

http://www.houseofthud.com/cartech/torqueversushorsepower.htm