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

[Roger]

Hi Jørgen,

Thank for the quick response.

For advertising I set the BLE interval to 10.24 seconds which equaled 3.5uA. Please see the following image: nRF52 Advertising - Current Consumption Example.png

For a peripheral connection I set the BLE interval to 2 seconds which equaled 5.4uA. Please see the following image: nRF52 Peripheral connection - Current Consumption Example.png

The power consumption is now significantly less. You're saying once the slave advertises and pairs/bonds with the master, devices must communicate between a minimum and maximum interval of 7.5ms to 4s in order to keep the connection alive.

The way I understand then the power consumption is as follows: (neglecting the advertising current consumption, this I assume will only happen once till a connection is established with the master)

Radio power consumption = (5.4uA * 3V) * 1/2s = 8.1uW

System power consumption = (2uA * 3V) = 6uW (Assuming RTC running and I have RAM retention)

Total power consumption = 14.1uW

Battery life = ( (300mAh * 3V) / 14.1uW ) * 0.7 = 44681 hrs = 1860 days

I hope I'm on the right track?

Kind regards,

Roger

[Roger]

That is absolutely awesome! Thanks for the great answer.