I have a Turbo Vado 5.0 SL purchased 1 1/2 years ago. I have ridden only about 1500 miles due to a surgery. I am now getting back to riding regularly and would like to add more power with the Range Extender battery. When I purchased the bike the salesman said it would be best to get an extra battery at that time so the batteries age and power are evenly matched. I know that can be an issue when two batteries are used in tandem. I would appreciate any helpful information.