Upgrading my ebike battery to give more speed and longer range
To increase the speed you need to increase the voltage. To do this you need to be sure that both your motor and your controller are rated for this. It is very unlikely that your motor is rated for > 36 V so you will burn it out.



Figure 1. The Freego Hawk with rear-wheel hub motor.

If the motor is in the hub (which it is in the Hawk) then that leaves you with no ability to speed it up. My Kalkhoff / Panasonic drives the chain of the bike from a motor below the front chainwheel so I was able to reduce the rear sprocket from 21 to 19 teeth to gain more speed.

I can't comment on the batteries other than to say 0.5 of a battery bank isn't going to be any good. I imagine you're going to have trouble with charging.