Are you installing a second battery pack on the scooter and need a switch to select which battery pack supplies power to the scooter?
If the vehicle has a transfer switch or power switch that only allows one of the battery packs to be used at a time, then the battery packs will need to be recharged with two different battery chargers.
The reason for this is that each battery pack will discharge to a different Voltage level since they not being used at the same time, and if they were both recharged with the same charger then the Voltage levels between then would become unbalanced and one battery pack would become overcharged while the other battery pack would become undercharged. This over and under charging would damage both battery packs and cause them to need to be replaced sooner than necessary.
However if both battery packs will be used at the same time without a switch to select which one provides power to the vehicle, then provided that the Voltage of both battery packs was equalized before installing, and that both battery packs have batteries that are the same brand and age and size, an adapter that plugs into both battery pack's charger ports and has one charger port could be made so both battery packs could be recharged at the same time with one battery charger.
To recharge two battery packs separately with one battery charger our item # SWT-154 is the one to use. Here is a wiring diagram showing how to wire it for this purpose.
When the switch is in the middle O position, no battery packs will be connected to the charger port.
When the switch is in the I position, battery pack 1 will be connected to the charger port.
When the switch is in the II position, battery pack 2 will be connected to the charger port.
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