After Psycho Scooter Scramble, life really wasn't ever the same. The practicality and robustness of the electric wheelchair as a project platform is unparalleled. I have no idea why it took me and my fellow psycho scooter scramblers so long to start messing around with electric wheelchairs. They are simple to hack, lots of fun to use, and are really efficient and well built machines! I am sure that this is just the beginning of fun and impractical things that we re-use the hacked electric wheelchairs for.
Hopefully this Instructable will serve more as inspiration for your own whack-job creative electric wheelchair builds rather than an actual set of directions to follow. I can't say enough how much potential there is for re-using these amazing machines.
Step 1: Get Electric Wheelchair
Now the wheelchair that you decide to buy will determine a lot about how easy or difficult the next couple of steps will be. If you are looking for an adventure, buy any old wheelchair you see in your price range and saddle up for a few hours or days of troubleshooting and hacking.
If you'd like to make things a bit easier on yourself, buy a wheelchair that you can test and make sure it works. If the wheelchair's batteries are dead or don't hold a charge, don't worry about it as that's an easy replacement. The unit should however power on, not give any trouble codes, and drive around. If it does these things, load it into your car and take it back to your cave.
Audrey and I purchased 4 wheelchairs in one day a few months ago and spent an average of $150 - $250 per wheelchair that met these requirements. Some even came with fully functioning batteries!
Bring ramps for your car or truck if you can, and drive the wheelchair right inside. It will make life easier. Otherwise, bring a friend and do some heavy lifting.
Step 2: Triage and Possibly Replace Batteries
We found some old batteries that were part of a very large uninterrupted power supply from a forklift retailer in East Oakland who was selling them at a good price. Battery prices vary wildly - do some research before pulling the trigger on replacing the wheelchair's deep cycle batteries. Used batteries are just as good as new ones if they hold a charge.
Replacing the batteries is electrically pretty straight forward - it's a simple swap, just make sure you hook up the wires exactly as they were on the dead batteries. The batteries are wired in series.
The batteries we replaced on this particular model were just a few inches larger than the batteries that we removed. That's not ideal, but it's not the end of the world. We modified the battery compartment a bit to accomodate the larger newer batteries.
Note - our replacement batteries are sealed and therefore can be turned on their side. If you are not using a sealed battery it must remain upright.
We used plumbers strapping to lock the new batteries in place on their plywood shelf.
Step 3: Remove Chair Part
Remove the chair by unscrewing the locking pins in the shaft of the bracket and pull the whole assembly off the motorized base. I decided to reuse the bracket on the bottom of the chair as a bracket for my work surface, so I removed the bolts from the chair and isolated the chair bracket.
Step 4: Weld Bumper
The bumpers are simply a strip of 2" x 1/8" steel flat bar welded in a loop around some 3/4" square stock. The square stock is welded onto the steel base of each wheelchair.
Step 5: Check Level
Step 6: Make Bracket Level
Step 7: Mount With Sturdy Platform
I recessed the bolt heads to retain the flat work surface. Also went with hex bolts instead of carriage bolts because I foresaw removing these planks from time to time if I wanted to bolt on other tops to the motorized base.
Step 8: Charging
Each battery charges separately and the process lasts overnight. The chair has good battery life when everything is charged and can be driven for several hours.
Step 9: Operation
Simply pick up the controller module and operate the wheelchair while walking along side it. The total load capabilities for the wheelchair are about what a person would weigh. I'm sure it could take a whole lot more, but I tend to make multiple trips rather than overload the thing and risk a problem.
In the future I'd like to put a few tie down points onto the sides of the 2 x 6 work surface so that projects and supplies can be strapped down if need be.
While not toting piles of metal or heavy boxes, the robo pallet is fun to ride around on like the Silver Surfer or Michael J Fox in Teen Wolf.
There's a whole lot of potential here for the electric wheelchair platform. I recommend it to anyone looking for an easily hackable, powerful, reliable motorized base. Wireless control of the electric wheelchair is not easy, but definitely possible. See steps 5 and 6 from Psycho Scooter Scramble for directions how.