battery life estimate

[Ridhi]

i have nrf52832 using nrf sdk version_17 and s132.

I have application for logging

i have followed steps:

1). intially device in sleep mode

current: 0.35 micro Amp

2). press button for 5 sec and then device advertises for 30 secs: 

current: 84.29 micro Amp

3). connect on nrf connect app for mobile

displays services and characteristics 

current: 740.40 micro Amp

4). chip erase 5 secs: 14.81 mA

5). takes about 100 logs in interval of 2 secs

each log: 7.03mA 

amidst logs: 2.11 micro Amp

so total 100 logs almost take 3min 22 secs and current: 1.57mA

6). disconnect and then advertise and connect and notify enable to get data: 

data log getting current: 741.20 micro Amp for 52 seconds

I am using coin cell battery CR2450 LITHIUM 3V

attaching power profiler trace.

pls help to calculate the life of device

[Karl Ylvisaker]

That is strange - I have had no problem with this in the past, and I tested this just now on my end by uploading an entire SDK as a .zip file without issues.
Are you getting any error messages or warnings when you do this? Does the upload being after you have selected the file?

Either way, I do not think you will need to upload the trace to make this estimate, since I would need to know a lot more about the regular operation of the device before I would be able to make any estimates myself.

Therefore, I suggest that you make the estimates as described earlier and compare them with the capacity of the specific battery you intend to use, to estimate the battery life of your device.

Best regards,
Karl

[Ridhi]

ppk-20220118T084110-data-logger.rar

[Ridhi]

i have shared you the trace:

functions:

1). unconnected: giving about 0.35 micro amp

2). press button for 5 secs: advertise for about 30 seconds with adv interval as 2000ms

3). connect on nrf connect app for desktop connection interval 1000-1000ms

4). press button for 5 secs put device in data logging mode take about 96 logs each of 29 bytes after 2 secs interval

5). press button and put device to sleep mode giving about 0.35 micro amp again

6). again press button for 5 sec and put in advertise mode

7). connect on app and enable a notification and get data 

CR2450 lithium 3v battery life has to be estimated

[Ridhi]

gentle reminder

[Karl Ylvisaker]

Hello again, Ridhima

As mentioned, it is hard for me - or anyone else - to make any prediction about the battery life of your device based on the provided information.
For starters; while you have detailed the different functions and operation of your device, you have not mentioned anything about how frequent or many of these wake-ups you will have, or how long it will remain in the connected state, etc.

I suggest that you use the PPK II to make some predictions on what the average current consumption will be for the duration of one of these button-logging-connection scenarios will be, then make an estimate for how often this scenario will happen, measure the average current while in-between these scenarios, and then finally calculate how much of its time total will be spent in the power-draw scenario, and how much will be spent in sleep.

To illustrate this, say that the average current consumption during the button-logging-connection scenario is 1 mA, and that the sleep current (in-between scenarios) is 50 µA. Lets also assume a battery capacity of 220 mAh.
If you estimate that each scenario lasts for 1 minute, and that it on average happens once every hour, you will have an overall power consumption of ~66 µA.
If your battery has a capacity of 220 mAh, the battery life expectancy is 220 mAh divided by 66 µA, which yields roughly 3333 hours, or ~140 days.

Now, do the same calculations with the numbers you estimate for your device, to estimate the battery life expectancy for the device.

Best regards,
Karl