####################################################
red---------(+)-----(+)
pack1 pack2
black-------(-)-----(-)
Parallel is where you split your lead wires so you have a red on each plus
and a black on each -, the available amps are added, so if you have two
20AH 36Volt packs, you would have 40AH at 36Volts.
#################################################
red---------(+)
pack1
(-)--------(+)
pack2
black------------------(-)
Series is where you connect Red(+) on one pack to Black(-)
on another pack, then connect your Red(+) Lead wire to
Positive on one pack and Negative on the other pack.
This gives you the same available amps (20AH) but the
voltages are added to get 72Volts