Is heart rate service the correct thing to use for power consumption efficiency?

[tyler]

I am developing some firmware using SDK 8.1 where power consumption is absolutely critical. The firmware will make a ble connection between the central and peripheral device and after that does almost nothing except for every couple months the peripheral will send it's battery level to the master device. I am wondering if it makes sense to use the heart rate service for this? My gut tells me know since I figure it probably is a power hungry service. I could be wrong though. Basically, I am asking what the most power efficient way to send a small piece of data from the peripheral to the central every couple of months would be.

[endnode]

First note: if power consumption is so critical why you don't use the best available HW and SW (= nRF52, S132 stack and nRF SDK v14 - in case you really really need to stick with nRF51 then S130 and SDK V12.3.0)?

To your main question: it seems that you know what is exact profile of your application activity over time (what adv. interval you want to use, when the device will be ACTIVE/POWER ON SLEEP/POWER OFF, when/how long/what parameters will be used when under connection) then you can do some modelling and find out which of these modes will contribute dominantly to your power consumption. Then optimize your profile with this in mind. It would be kind of dumb to advise just based on feelings (which is what we do here right now I'm afraid... "my FW does almost nothing except little bit of this and that...")

[tyler]

Using the best HW and SW is a good idea, I should look into that. Do you have a ballpark estimate of how much better the power consumption would be using better HW and SW, i.e. would it be a large decrease like 40% or a small decrease like 1-2%?

[endnode]

Come on, you won't get any reliable judgments by asking some random folks on and internet forums;). You need to build some prototypes and measure it, that's the only real way forward. Looking to the specifications and doing "back of an envelope" guess based on numbers there you should expect (if you know how to optimize the HW and FW!!!) anything between 10 and 50% of lower power consumption when going with nRF52810/52832 instead of 51x2x, but real numbers depend on so many factors that it's useless to discuss it further here.

[tyler]

Is there a reason you would stick to sdk version 12.3 instead of upgrading to sdk 14 on the nRF51 device?

[endnode]

Sure, nRF51 is not supported in nRF5 SDK after v12.3.0;)