No, do not disassemble battery cartridge.

No, DongCheng chargers have a overcharge protection. For example, the DongCheng Charger (FFCL20-04) communicates with DongCheng 20V MAX Lithium-Ion batteries to detect its charge level. Upon reaching a full charge, the charger goes into a maintenance mode and actively monitors the battery's charge level to keep it fully charged.

No, the use of a converter or power inverter may cause damage to the charger and will void the warranty.

Some rotary hammers can do light demolition work, like chipping tile. But for heavy or extended demolition work, a demolition hammer is the better tool for the job.

In order to use a cut-off wheel, the DongCheng grinder must be equipped with an approved cut-off wheel guard for the particular grinder. Consult the grinder's Instruction Manual to determine the proper guard. Also, grinder accessories must be rated for at least the speed recommended on the tool warning label.