电池组的英文：
battery

It is the positive of the battery.
这是电池的阳极

The battery is flat.
电池快没电了。

The capacity of the batteries depends on the brand and type of batteries used.
电池容量决定于所用电池的类型和牌号。

The bacteria battery could become as small as a household battery.
微生物电池可以像一般家用电池那么小。

It is mains or battery powered.
它是由电源或者电池供电的。