Scratch Build

[Frosty]

I have been looking at a number of websites and info regarding Li powered power chairs. So far I wonder about the balance for the chair mods I have looked at. My requirements include a seating system custom from AMY built for me and would have to be fitted to any new base. I really like the Li concept and conversions since I am looking for increased range and 'off road' capability.

There is an electric bike shop just next to me and I have discussed a number of options with the owner, but what I see now makes a whole lot of sense to me and the shop owner is will to work on any project I might have. Any thoughts on balance for power chair base with a tilt/recline/recline leg lift configuration? Are there thoughts on a new build?

[JoeC]

Lithium batteries are great, but they're light- that raises the chair's center of mass. I understand that powered seating is an absolute necessity for some people, but it often has a negative effect on your center of gravity- often moving it up. If you want offroad capability, my advice would be to do whatever you can to keep your center of gravity LOW.

[ex-Gooserider]

Agreed that you want to keep the center of gravity as low as possible, but you also may need to think about having some sort of way to move the seating system back and forth on the chair as you do tilt / recline stuff... It is very important to try and get as much of your weight over the rear drive wheels as you can - BM results seem to suggest that a balance of about 80% on the rears and 20% on the front casters seems like a good target. (assuming you can lean forwards when going up ramps and such) Problem is that if you have that much on the rear when sitting upright, your center of gravity will shift behind the rear wheels as you tilt back, and tip you over backwards... Thus you will need to have some kind of linkage that will move your seat forward as you lean back so that your balance stays in the right place.

ex-Gooserider

[Martin O Refurbisher]

I would commend you to read everything that Burgerman (BM) has written on the subject. It is still at an early stage, and there are many points that you will need to cover. If you are in UK, then the obvious route to follow is that that BM has taken and start with a Sunrise F55.

Good luck, and do post your progress.

Best,

Martin

[Burgerman]

Have a read here - my lithium setup. Batteries are almost half the weight, but 3x the usable watt hours. (2 or 3 times the speed and about 3x the range)
You may also have error messages, and battery meter errors to contend with.

http://www.wheelchairdriver.com/BM-MK3- ... rchair.htm

and charging these properly isnt simple.

http://www.wheelchairdriver.com/BM-MK3- ... rchair.htm

and... to take full advantage (speed for free!)

http://www.wheelchairdriver.com/BM-MK3-roboteq.htm