Battery life

When transmitting data, an nrf52840 dongle consumes around 1000 uA (1mA) In sleep mode, it consumes 20 uA. A Good coin cell battery can have around 200 mAh. So sleep battery life. 200mAh/20uA = 10000 hrs in deep sleep mode. 10000hrs > 416 days > a bit more than a year.

In transmitting: - Single press activates advertising, and if there is no next activity for half a second then advertising turns off. - So we have a consumption of 1mA during half second for a single press. So about Coin cell has 200 mAh -> 200 * 3600 mAsec or 7200 single presses.

But in general, cheap batteries will have less capacity.

Consumption can also vary on different boards. My measurements were made with the nrf52840 dongle.

How does this compare with HID?

2532 uA (2.532 milliamperes) constant draw is seen on an HID connection with an nrf52840. So it consumes more than 2.5x more power.