Looks like my poor mans Hybrid just might have merit!

[ttoyoda]

The freewheel you are looking for is called an
overrunning clutch

http://en.wikipedia.org/wiki/Freewheel

[ttoyoda]

And you *are* planning to wire this up so that when the brake lights come on the motor shuts off automatically, right?

[Nerys]

No. It will be a dead man switch. I will have to HOLD the button in order for it to go. If I am hitting the breaks clearly I will not be pressing the button :-) Thats why I canned the "foot switch" concept. I fear I may mash the break with my right foot and "mash" my left foot in instinct as well and if its on the switch .... so its a dead mans hand switch for safety.

ttoyodaa thanks for the link EXACTLY what I was looking for. Now to find one and see how complicated it will be to retro into my design :-)

[ttoyoda]

Well if it was me, I might mess up and hit the button by accident, if I was in the "learning" phase of using this device.

I think your basic idea is sound. If you had some additional way of controling the connection of the motor to the axle, then you might be able to recharge your batteries. Maybe you could sense manifold vacuum to detect coasting or slowdowns to to the engagement. There is something called a magnetic clutch that can be engaged or disengaged electrically. Then wire it up so you only try to charge ONE battery at a time, and make a selector so on the next slowdown the next battery gets charged.

[getnpsi]

I think a minivan is the perfect candidate for its rear payload area. I do not want to see this thread die, or your plans Nerys

[IndyIan]

Originally Posted by Nerys

I am not sure. My original idea was a free wheel like on a bicycle. IE spins freely when no force is applied. I figure "heavy duty" version of that must exist??

You might get away with using 1 or 2 good bicycle free wheels, my rough calcs say one deals with 400ft/lbs of torque quite well. Me at 220lb mashing down one pedal while pulling up on the bars must be around 400lbs of force, doubled by the crank arm diameter vs the sprocket diameter into an equal rear sprocket diameter, heck maybe its 800 ft/lbs but that sounds a bit high.

Do all of your torque multiplication after the freewheel and you should be ok. They might not like high rpm though, bike wheels are big and don't see 50mph very often. If you can't find a heavy duty free wheel right away these might be good enough for proof of concept anyways.

Cool idea!
Ian

[dremd]

there is also a similar (one way) part in many starters, might be worth a look.

[Nerys]

Some questions. BUYING an electric motor may not be too far out of the range of feasible. HOW MUCH Horse Power do I need? How do I even figure this out? I see even 50 and 60hp electric motors for under $500 !! thats a lot of money More than I have but maybe in a few months I could scrounge it up.

WHAT type of Horse Power do I need? How do I figure it out? Vehicle mass 3700 pounds.

[IndyIan]

Originally Posted by Nerys

WHAT type of Horse Power do I need? How do I figure it out? Vehicle mass 3700 pounds.

Thorough bred hp is good for topspeed, clydesdale hp gives you more torque...

As for how much hp your motor should be, what does a Prius have? 25hp? You have probably double the drag and weight by the time you add everything so double a Prius. I guess it also depends on when you will be in electric mode. 35mph and under? 60mph up hills? For most industrial application the general rule is that you need half as much hp using an electric motor vs a gas motor. But if you only need 30 hp to go 50mph on flat ground and thats acceptable maybe its all you need.

Not to burst your bubble, but maybe something like a late 80's dodge shadow that shared many parts with the late 80's caravan would be a better platform for this. I seem to recall that there was an AWD caravan back then and hopefully the rear axle is interchangable with the shadow? I don't know for sure it would be a simple swap but it would put you ahead in aero drag and lose over 1000lbs in weight.
I'll bet a good running dodge shadow is sub $500 to get you started.
Ian

[DifferentPointofView]

When the motor is assisting the ICE, it's pushing it down into a less efficient part of the BSFC map. You'll be getting considerably less power from the ICE, but it will only be using a little less fuel.

Just to clarify, but the same EXACT thing happens when you do aeromods. Less load on the engine= less on the BSFC map, but you still use less fuel because you use less air, and you need a correct air/fuel mix for it to burn correctly.

Sounds like a good Idea to me. Would this be possible with a 4wd vehicle?