Hello,
We are designing a wearable with TI's CC2541 Bluetooth SoC simply acting as a Beacon (SDK(v1.4.2.2) Example: SimpleBLEBroadcaster). To power the circuit, we are using Panasonic's CR2032 coin cell.
Challenge:
How to rightly calculate CR2032's battery life with peak current (~11mA) during advertising and 1 micro Amp during sleep? We know that capacity of coin cell decreases with higher peak current greater than 0.5 mA as specified by the manufacturer, so how to estimate the battery life theoretically and practically?
Theoretical Method:
To estimate CR2032 battery life for this application we used TI's tool to calculate expected battery life according to 5.6 Using Excel Spreadsheet for Calculations section in the Application Note AN092. We used oscilloscope to get peak current values during different states in advertising for our own custom board and inserted them in the Excel sheet to determine battery life. In this calculation, we used battery capacity to be 220 mAH, but according to SWRA349 we know that the actual capacity will be less than rated capacity due to peak current. Below is the snippet of the excel calculations:
So, WHAT value of battery capacity should be insert in this to get the theoretical result?
Practical method:
How can we perform an experiment to find cell's capacity practically without observing the apparatus for large number of days (2-3 years) to claim exact battery life of our product.
P.S. we are also using 47µF capacitor in parallel to CR2032 coin cell to reduce the effect of high current drawn as recommended in SWRA349
It would be highly appreciable if you can help us out in this as we need to start shipping our product by next month and need to convey minimum battery life to our customers.
Thank You,
Madhav
