Sometimes it is necessary to start using the SBM board by connecting the charger to P+ and P-. The SBM module is internally disconnected the same way as it is when it protects the battery pack from overcharge or overdischarge.
It is also necessary to use a suitable charger - chargers for LiFePO are inappropriate, because they need to sense the voltage first to start charging. For four LiFePO4 cells it is enough to use standard charger for car-starting lead acid batteries, or any 12V small power source from modem or stereo for example, or any other small consumer electronic which uses 12V power source.