The unit of battery is milliampere. The recording time of some voice recorders is up to hundreds of hours ,and some only have several hours. According to different purpose and scheme, the power consumption is different. When the battery power is same, the high quality of recording will need scheme of high power consumption. please choose the products according to practical needs.
Some voice recorders has integrated with camera at present, used to take video ,which includes audio and video . In that case the power consumption is higher than recording voice only.