I'm not sure I understand. Correct me if I'm wrong but isn't a battery tender used to maintain the charge on your battery when you're NOT riding it? If so, you may have misunderstood the issue I'm having. The charging system in my scooter doesn't work (but I can't pinpoint what has failed). So I can only ride until the battery dies (I've figured out how many miles I can go on a full charge). So my hope is that I can ride longer on a bigger battery than a normal scooter battery.