Hi Marcus and
to the forum.
48V is much too low for a freshly charged 48V lithium battery, as it should be between 53V and 58V dependant upon the cell chemistry and the number of cells in series.
It sounds to me like the charger is not charging correctly
(unless your voltmeter is reading very low ), so make sure you have the correct input voltage selected on the charger
(if there is a switched 110V/220V option to select it).
Most chargers usually have the maximum charging voltage marked on the casing, so it will probably be 54.6V, 58.8V or 58.4V, and you might be able to check the charger's output voltage with your voltmeter to see if it is correct.
If the battery is full, all three LEDs on the throttle should light up, if you only have the single red LED lit, the battery voltage is too low.
A 500 Watt battery is not ideal for a Magic Pie Edge running on the default 18 Amps maximum current setting, as it can pull up to 1000 Watts under heavy load. You would need to reduce the maximum current setting of the controller to 9~10 Amps to prevent the battery from being overloaded.
I suggest that you contact your supplier directly and explain the problem to them.
I'm assuming that you have the BAC-601 Smart Display, in which case there are two types
(early and late) and you need to have the later type to be compatible with the Magic Pie Edge controller.
Torque arms are not supplied by GM and are not part of the motor kit, therefore if you have ordered and paid for these in addition to the kit, you will need to contact your supplier and inform them that they did not arrive.
Alan