PowerWalker LiFe Battery System 48-100 Mode D'emploi page 26

(d) Use battery cable to connect the battery module and inverter
module. Make sure the polarity of battery module are correctly
connected.
RED connector to the positive terminal (+)
BLACK connector to the negative terminal (-)
If more than one battery modules are connected, use battery
cable to connect master battery module and remaining battery
module one by one.
#1
Master battery module
#2
23
#10