RE: "electric power" batt. Brand....any good?
Depends on your motor. Those batteries are 8C which means they can be discharged safely at 8 times their capacity.
Example:
1000Mah battery can be discharged safely at 8000Mah or 8 amps.
You need to match your battery capacity and discharge rate to the amount of current your motor pulls.
TIP: Don't go el-cheapo on your batteries, you will probably regret it.