nRF52 'online power profiler' battery life calculation check

[Roger]

Good day everyone,

I would like to utilise the nRF52832 BLE chip in an application that requires radio communication between a master and slave. The slave needs to be powered by a coin size battery and ultimately I would like to explore an energy harvesting circuit that might replace the battery.

To test the initial phase of the concept, I made use of the 'power online profiler' on devzone.nordicsemi.com/power to determine the energy consumption during a broadcast event by the slave. Once a connection is established by the master to slave, I then would like to exchange data only once a minute.

My calculations are as follows (please see image):

nRF52 Current Consumption Example.png

Power = (161uA * 3V) * 1/60s = 8.05uW

Using a 300mAh @ 3V coin size battery with 70% efficiency:

Battery life = ( (300mAh * 3V) / 8.05uW ) * 0.7 = 78261 hrs

Does my calculation bare any fruit? It seems to be a bit unrealistic to me.

Looking forward to someone's response.

Regards,

Roger

[Jørgen Holmefjord]

Why are you multiplying by 1/60?

P = U * I => 161 µA * 3 V = 483 µW

This should give approximately 54.35 days with your battery.

[EDIT:] Maybe you divided by 60 since you mentioned you wanted to send once a minute. If you are in a connection, the devices will need to communicate more often to keep the connection active. The max connection interval is 4 s. From the image you provided it looks like you have calculated the power for advertising. It is possible to set an advertising interval of up to 10.24 s.

Best regards,

Jørgen