I purchased a 500 watt front wheel motor kit last April and obtained my own lead acid battery configuration. The existing bike with the 500 watt motor is a dream. I have been running it at 48 volts (instead of the system designed 36V). I’m using 4 x SLA 12v 9A/h batteries and have put them into a custom designed box you can see from the photos. It does just under 50 km/h with the increased voltage. I burned off a stinky 50cc petrol bike the other day. Running at 48 volts, I believe the motor is delivering around 750 watts at an average speed of around 25 to 30 km/h. I am getting a good 25 km with some pedal power before the batteries drop to 40 volts. The batteries have never dropped below 36 volts. I notice that some of the yanks are using Dewalt 36v power tool batteries in series at 72 volts. This almost doubles the power of the motor, amazingly without detriment to the 36 volt motor system. I have been running mine at 48 volts with no problem whatsoever. It is my belief that increasing the voltage increases the range as well as the power without increasing battery amp hour. I am game to try 72 volts. The yanks seem to be going for smaller batteries at higher voltages. I bought a managers special bike from Big Dub, reduced from $250 to $150. It is fully sprung, I thought it might fall to bits but its been great. I have belted it around everywhere over the last nine months, even over rough ground. The only thing that went wrong was the control wire to the hub chaffed on the forks with the up and down movement and I came to a grinding halt. I rejoined and insulated the wires and re-routed them, all ok now.