Electric Scooter Needed for Hybrid Concept

Ken Gracey

Hey there,

A customer read my article in ROBOT about using a small gasoline engine and an alternator to generate power. This customer is really heavy and uses an electric scooter to get around. I imagine it is one of those three-wheel "Lark" type of scooters.·More than once he ventured out and couldn't make the return trip home when he ran out of power.

So he asked me if there's a way to retrofit·the device·with a gasoline engine and an alternator. As I recall, wheelchairs use big batteries so they should be able to handle the current generated by an alternator if they are in a low-voltage state.

But where can I get a motorized·scooter to experiment with? These things are darned expensive.

If anybody has some tips let me know. I'm willing to do the work for free with Parallax parts to see if I could extend the range of one of those devices, but I don't want to buy one.

Ken Gracey·

W9GFO

Watch Craig's list.

Just two days ago I picked up an electric wheelchair for free. The kind that has two drive motors powered by two group 24 batteries. It's made to carry 300 lbs a distance (claimed) of 19 miles.

Right now in my area there are two others for sale for less than $300.

Here's just one example;
sacramento.craigslist.org/for/382488859.html

John R.

Ken;

Check with the local hospital and/or nursing homes. They may have a "spare" that they would be willing to lend out for testing and development of the concept. Another source might be the fine folks and MD (Muscular Distrophy).

Also, if you can, find out what specific disease/disability your customer has, and see if their organization might be willing to help you out. If you can get this information, you could try his local chapter, your local chapter, and the national group.

I've PM'd you with another possible option.

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John R.
Click here to see my Nomad Build Log

Tiger

Ken - All of those carts I've seen have a range of about 20 miles. Some as many as 30 miles. They generally do have two big 12v batteries. Therein lies the problem. The batteries are in series to get 24 volts so you'd have to have a 24 volt alternator to charge them. I'm thinking that if this guy isn't getting very far in his cart, his batteries are probably shot. They are normally only good for about four years. If the guy got new batteries, he'd probably be fine. If he get the alternator et all, he probably still needs the batteries. I don't think I'd jump into this one.

...Tiger

John R.

Ken;

If you haven't found a scooter/cart yet, another source might be a big grocery store, or one of the "big box" home centers. They usually have a few of these available for shoppers, and you may be able to borrow one, even if only for a day or two at a time.

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John R.
Click here to see my Nomad Build Log

Capt. Quirk

(You all ready have what you need (in parts)). You could do it with one of your exsisting bots. Add a storage area above your engine, so·that you can load it down with 350 - 450 lbs of ballast for testing.

You could make a data aquisition system with a couple current sensing devices, to test your amp draw and charging capabilities and never have to buy a scooter.

<<==Bill

·

Safe Cracker

This is the reader in question. I am a very heavy person and even with a scooter well rated for my weight that 20 miles or 25miles range given in manufacturers literature is pie in the sky. My scooter uses 2, 22NF style 55AH gell cells. I am very aware that the batteries wear and am used to replacing them about every 16 months.

The real world is not where they rate these scooters at. Though ADA has been the law of the land for 15 years I still find obsticles that were never planned for. Curb cutouts that are unusually steep on a wickedly uphill stretch of street puts me climbing ramps that terrain plus ramp are 30 to 40 degrees above horizonal. A uphill stretch of street bleeds the batteries more quickly. Carpeted floors eat up more battery life. Soft ground like a concert in the park or an air show can leave me looking for a place to plug in after a mile or two.

Even having my emergency cord along is no great relief. I sit for 30-45minutes and gain about 3 level blocks of distance. 1 block or a bit more if it is mildly uphill.

Now imagine an emergency, there is no light rail, or buss service. Your ride has had an accident. How nice it would be to head a couple of miles acros town at top speed, 5 miles an hour, but to be assured you would make it home.

Thank you all. The wheeled community needs your ideas.

D Faust

Could you use optoisolators to disconnect the bateries from the series and wire them in parallel to charge them at 12V. (With an alternator) You wouldn't be able to move while charging (unless you want to run the motors off 12V for a little while), but it would get you there.· Let me know if I need a diagram.


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Post Edited (D Faust) : 8/10/2007 12:44:52 PM GMT

Capt. Quirk

What make/model scooter do you have? and do you have a link so we can check it out?

Thanks

Bill

Safe Cracker

Unfortunatly the maker only makes 12 volt grocery store carts at this time. I understand they dropped out of the other side of the buiness because there was a pound of medicare paperwork for each scooter they turned out. Fortunatly they still support my scooter even after 5 years.

Would a tech document from the maker of the speed controller help? It gives diagrams and typical features that are equivalent to my owners manual diagrams.

Email me for the tech document.

Regards
Ray

Bean

Ray,
If it is 12 volt then that is GOOD news. Since most alternators will be setup for 12 volts.

Can you just post the documents here ?
Bean.

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Teacher: What is the difference between ignorance and apathy ?
Student: I don't know and I don't care
Teacher: Correct !
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www.hittconsulting.com
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Safe Cracker

12 Volt is the current version. Mine and most wheel chairs or scooters are 24 volt. How do I post it here? Is there an upload direcory?

Bean

Ray,
· Click on the "Post Reply" button, then at the bottom is a button "Attachment Manager" click on that. Click on "Browse" and find your file. Then click on "Upload File".

· Or you can e-mail them to me and I'll post them for you. "forum at hittconsulting.com" (use "@" instead of "at")


Bean.


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Teacher: What is the difference between ignorance and apathy ?
Student: I don't know and I don't care
Teacher: Correct !
- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - -
www.hittconsulting.com
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Safe Cracker

Ok here is the document.

A few thoughts on the project so far. Ideally the device would be usable while on the move. This would prevent a carbon monoxide problem where a user parked in a relatively enclosed space because cold or inclemate weather. Is there a chance to replace the diodes in a 12 volt alternator with a voltage doubler circuit? As was pointed out earler most wheel chairs/ scooters have sufficent battery capacity to sink most of a alternators current in a quick charge mode while using the rest to drive down the street. Think clean spill free fuels like the propane cylinder.

Thanks

Gadgetman

Why modify a 12V alternator when there are 24V versions available?
(Many trucks use 24V systems... )

What you really want is a 'hybrid' gas-electric system, something like what is used in the Toyota Prius or similar models.

That is, a small engine running at all times to produce electricity both to drive the scooter, and to recharge the batteries. Then when you enter an area where the exhaust or noise is 'undesired', you can switch off the engine, and run just from batteries.

To get this, you need an engine(rated to produce enough power to match the electric motors at a normal 'easy terrain' consumption), a 24V alternator, the charge regulator or relay from the same truck you nick the alternator from, and finally, a small computer to 'keep an eye' on the battery.

You CAN run without the computer, but having one may help with fuel economy.
(I assume that you don't want to bring more gas than necessary.)

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RickB

Quirk:

That > is < an electronic speed controller. PWM at 19.5 KHz. The pot adjusts the pulse width.

Rick

Capt. Quirk

My mistake,

I thought the·Wig Wag was the sole controller.

Bill


Post Edited (Capt. Quirk) : 8/13/2007 12:53:30 AM GMT

Safe Cracker

As you can imagine the project could be configured as anyting from a emergency device to a system that uses a fuel as the primary energy input. Both systems would have their places.

As for the speed controller, yes it is pretty through in its functions. Regenerative breaking, fault detection, battery monitoring and PWM controll. I especially enjoy the way it scavenges energy with the regenerative breaking.

I believe that I was caught expecting a lot more distance one time I was in a convention hall that had been setup with rugs for sound control. The breaking effect of the rugs left me recharging before I left the convention hall with the show half covered. My stop and start for he exhibits had killed my batteries very early where I was acoustomed to reusing the energy scavenged on each stop.

Gadgetman

Just thinking...

In convention halls and such, they probably wouldn't like it if you started a gasoline engine...

What about a fuel-cell using Metanol?
http://www.efoy.de/index.php?option=com_content&task=view&id=13&Itemid=56

They claim that it doesn't make more noise than a typical computer...

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Bean

I agree with Gadgetman, a gasoline engine is going to have very limited use. With the fumes and noise you may not even be able to use it outside if other people are around.

How about using a new battery technology ? Ni-Mh, Li-po, etc.

I guess there is not such thing a boost converter for that much current (to run the battery down further).

Bean.

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Teacher: What is the difference between ignorance and apathy ?
Student: I don't know and I don't care
Teacher: Correct !
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www.hittconsulting.com


Post Edited (Bean (Hitt Consulting)) : 8/15/2007 5:15:48 PM GMT

Gadgetman

Li-po tends to have 'heating issues' if you're not careful...
(Read: burst into flames... )
Most battery-techs doesn't like the stress and abuse this kind of vehicles pose.
(Most electric cars use Lead-acid)

Besides, even with new tech, he may not get much more than 50% boost, and will still get stranded on the carpets.

A liquid 'supplement' will dramatically increase range without adding too much weight to the scooter.

Gasoline will work OK outside, so if he KNOWS he can do whatever he needs to do inside while running on batteries, that is one solution. (Gasoline is easily obtainable)

Methane fuel-cells are quiet, produces no hazardous wastes(unless someone gets P! O! because of the water-droplets...) but the fuel may be slightly more difficult to obtain.

Propane? I don't know what kind of engines/generators are available, and their characteristics, but big canisters(gallon or more) are awkward to handle, so he may need help with replacing empties with full ones. Small canisters used for camping are nice, but are comparatively bl**dy expensive. (I do a bit of camping... )
That said, a 'friend' of mine - who lived in Florida before - rebuilt his classic Beetle to run a 'trifuel' setup.
(Injection system using gasoline mixed with propane, and also had a catalytic converter for Hydrogen, to give it 'a bit of help' during accelleration. He claimed 146mpg on the gasoline... )

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walice_drel

You can get them at pep boys auto for around $199 here in NY.

http://www.pepboys.com/transportation/personal_transportation/9485022_pal_pt.html

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Safe Cracker

Thinkingfrom the emergency use standpoint I was thinking the fat version of the propane camping cylinder would be perfect. It combines as large a cylinder as is easily swaped and a reasonable weight. I understand that an internal combustion engine will not be usable indoors but will still have value. The scooters normaly come with gell cells so that they are safe to carry on aircraft. I assume that the propane system would be aircraft carryable by removing the cylinder. You buy a cylinderr when you land and you are set.

The smell issue, leakage, and safety issues make me think that a gasoline system would not be usable, but the basic research done on one might make a usable emergency power system available in the future.

Thanks all

MarkS

To answer Ken's original question, check out local pawn shops. I'm endlessly surprised by the number of power chairs I've seen in pawn shops. I guess they were hard up for money, but anyway...