I wanted to see how much faster a 48V battery would push the 36V 500W motor. I emailed Jason at ebikekit.com and found out that I need up install Anderson PowerPoles in place of the 3 standard bullet connectors on the controller. Jason also stated that the controller was 48V capable as it is. No modifications needed! The bullet connectors didn't seem to critical for a test so I plugged in an extra heavy duty 12V 18AH sealed lead acid battery in series with the 36V 12AH battery to make a 48V battery. This is the result of an unhindered speed test!
With a 36V battery fresh off the charger, the ebikekit motor did 28.6 mph. With the 48V battery fresh off the charger, the ebikekit motor did 36.3 mph! That's a 7.7 mph improvement. I need to give it a test ride in the morning to see if it responds the way I expect it to. Right now, I can get up to almost exactly 23 mph on level ground. If the 25% improvement holds up in the real world, I should get close to 30 mph at 48V!