I would think that H-Bridge would be really marginal for a wheelchair. You might consider using these instead:http://www.ebay.com/itm/50A-Single-H-bridge-Motor-Driver-Module-PID-F-Arduino-Intelligent-Car-Robotic-6-/291041496732?pt=LH_DefaultDomain_0&hash=item43c36cce9cThese work really well, and will withstand significant over-load for short periods. I use them with motors that draw up to 85A at stall, and have never blown one, other than when I did something stupid.Regards,Ray L.
Those look awesome I'm also looking for one with higher volts. I am thinking about modifying a 24v scooter.