Let me just throw out some advice to new people who haven't bought one yet.
You will likely need at least a 36v15 AH SLA pack or 36v10AH lifepo4 pack before you are satisfied with the range. You need almost twice as much AH in an SLA (lead -acid) battery as you do in lifepo4 because of the peurkert effect. If you have to get SLA, I recommend getting the EB-20-12 which is the B&B 12v20ah SLA's. They've been specially made for electric bikes and have been known to last to 5000 miles if taken care of correctly. I started out on 60v9ah SLA pack and it sucked really bad. I could barely get 6 miles out of it and that's with 50 % pedaling so more like 3 miles without pedaling. I would also say capacity over volts. I got a 36v20ah lifepo4 now. I chose capacity over more volts because I found that with the 60v pack, I rarely went over 25 mph anyway. I'd much rather enjoy a 1 hour ride on a 20AH lifepo4 pack than a 5 minute ride on a 60v9ah SLA pack. Nothing worse than seeing a gas scooter blow by you on the road because you ran out of battery. I plan on adding another 12v20ah Thundersky later this year, though.