Hi there, I recently purchased a scooter that comes with a external battery back. But due to weight, I've unplugged it from the scooter and ride without it. But after talking to multiple person, leaving the battery not charged up and sitting flat would make it useless after while, so that being said... what do I need to do to hook it back up? I heard if I need to hook it back up, I'll need to make sure the voltage are the same aka charging them both fully before plugging it back in. Or should I just plug it back in to the scooter and charge it from the scooter main port? Unfortunately, the scooter does not come with the charger that the battery takes and I'll have to either get an adapter to charge both of them to 100%. Please help me! Thanks!!!