Gas powered mobility scooter?

[GreenMantis]

I didn't really know where to put this, but it's an idea I have been thinking about. I know an old man who really depends on one of those things, and he gets around on it. Enough so that the limited range of the electric drive train is something of an issue for him. A gasoline engine would cure that issue.
The most obvious solution I see would be to build a gas powered d/c generator out of an automobile alternator, and mount it on the back of the thing. It could give up the big batteries it has now for smaller ones, to keep the weight down, and possibly make space for the engine. That way the thing doesn't need any changes to the control system, or drive train to make it work. I think direct drive for a gas engine is entirely unpractical, since it would require a complicated control system that would pretty much have to be fabricated from scratch. Also, it could still operate on battery power only for limited periods, whenever it's inappropriate to use a gas engine, like shopping at Walmart.
The first idea that comes to mind would be two small automobile alternators, with the regulator/rectifiers removed, and replaced with full wave bridge rectifiers, instead, with constant power to the fields. The way the voltage regulators for automobile alternators normally work is they attenuate the current to the field pole, so the output remains more or less constant all the time, regardless of how fast the engine is turning it. In addition, they are really 28 volt, 3 phase a/c generators (hence the name "alternator") rectified by a single diode to limit the output to 14v, by shunting half the duty cycle. So using a full wave bridge rectifier and a constant current to the field poles will give 28vdc, and two rectifiers in series would get a maximum possible 56vdc, that will be more than enough to charge any battery configuration. If the thing happens to be only 24 volts, then one alternator would suffice.
I once built an alternator that way to power my cb radio, when I was into that. 14 volts really isn't enough to run Toshiba 2SC2879's, they will only make about half of their full rated power output at 14v, they really want 18vdc to make them sing. It worked surprisingly well, actually, and it was dirt cheap to diy.

 

[Frankenstein]

It would work, probably well too. I've honestly wanted to make a gas powered Gen to power an electric motor for a bike but it's probably not going to happen, but anyway I do have full faith in that idea of yours. How would he start it? I'd assume it's not easy to work from a sitting position.

 

[bakaneko]

Will it be able to provide enough amps for starting from a stop or tough hills? Mebe keep the battery just for that and then less amps for straights or not too bad inclines?

 

[GreenMantis]

They make electric starters for the Predator motors on HF. I found a guy on ebay who has an impressive selection of electric starters for small engines. And one thing it wont be lacking is electrical power, so that should be super easy. I'm thinking that if I added a solenoid actuator for the choke, and wired that to the starter button, that should work okay. That's how GY6's do it.
The other thought I have on this is to convert it from lead-acid batteries to lithium. If the thing is going to be a hybrid, then it should be able to torque up a hill without the engine running at all, at least as well as it ever could have. The drive will all electric, and original. The only changes would be that we'll have a gas powered charger on board. A true hybrid. Ideally, we would want a large enough generator to charge the batteries, even while driving, or riding, or whatever it is you call it when you are getting around on one of those. Or at least provide as much power as the motors can possibly draw, that would charge any other time than when you are using max power.
A long time ago, I got given an old golf cart, without a charger, which was okay, I lived off the grid, and couldn't have used one, anyway. So I did the same thing, I built a generator on the rack on the back where the golf clubs used to ride. Then I put 3 solar panels up on the roof, in series, so it would get a little bit just sitting out in the sun. I got around all over the place in that thing.

https://www.ebay.com/itm/Electric-S...e=STRK:MEBIDX:IT&_trksid=p2055119.m1438.l2649

 

[Street Ryderz]

 

[KCvale]

I want one!

 

[Herman Klutz]

I think something like a 3 wheeler built like the old Indian Tri-Car would be the best bet for someone with a disability. The front part, that was a wicker seat, could be a place to store a walker, cane etc.. It is also large enough that it could be powered by electric and gas.

 

[KCvale]

I think something like a 3 wheeler built like...

....something new?

That build was a rocket sled ;-}

 

[Herman Klutz]

That would work, electric power on the front wheel, gas engine on the back wheels. Electric to get speed to start the engine, then use gasoline power.

 

[GreenMantis]

Not really, to qualify as a mobility scooter, it kind of has to be able to maneuver indoors. At least in public spaces like walmart, or the mall, or the doctor's office, those kinds of places. It also has to be able to get on the bus.