Estimated battery life with NFC and a writable BLE service?

[espruino-discuss]

Posted at 2020-07-21 by DanTheMan827

I'm working on a project that simulates NTAG215 tags from the puck.js which will communicate over BLE for managing the NFC tag data, but my question is how long would the expected battery life be in this situation?

I've read that with just a simple BLE beacon that the battery life is 1-5 years but I don't know how that would be affected by having NFC enabled.

[gfwilliams]

Posted at 2020-07-21 by @gfwilliams

Hi,

Actually NFC shouldn't affect the battery life noticeably at all - in fact I think the power usage measurements were taken with NFC enabled.

I think 5 years is very optimistic (if that's on the Espruino site could you let me know, as it'd be good to fix that) but I think 1 year+ would be absolutely fine.

Only thing to watch out for is to use NRF.setConnectionInterval(200) or similar as by default Puck.js will enter a high bandwidth mode when connecting/being connected to. It'll go to a low power mode after 1 minute of inactivity but depending on your use case, that could cause you higher power draw

[espruino-discuss]

Posted at 2020-07-21 by DanTheMan827

Oh, I misread, it was potentially 5 years without advertising...

http://forum.espruino.com/conversations/297334/

My usage when actually connecting to the puck would be to connect, transfer about 572 bytes of data, then disconnect... I definitely don't need high-bandwidth mode so that's good to know.

I suppose I could also increase the advertising interval and lower the BLE transmit power since it'll only need to function within a foot or two of the device that's writing to it and it doesn't need to be detected immediately since the application itself will be scanning in the background for it.

I don't have a target for the battery life, but I also don't want it to go flat prematurely if I can do simple things to prevent it.

[gfwilliams]

Posted at 2020-07-22 by @gfwilliams

Ok, that sounds perfect then!

My usage when actually connecting to the puck would be to connect, transfer about 572 bytes of data, then disconnect...

To be honest you might as well leave the connection interval alone then. It's only an issue if you were planning on staying connected to the device - if you connect and disconnect you're unlikely to have any problems