I just got this information about the battery life on the CEO of FOBO. I had asked if I could get extra batteries to keep in stock.

I will try to explain on the subject of battery, which you see, is happening during the winter.
Try to recall the old days of digital cameras; the flash wouldn’t work during winter, it needs to be warmed up before each use. Here’s the gist – battery has 2 parameters, voltage and charge (the amount of current residing inside the cell). I will put these in point forms;

1)A new battery has a nearly full charge, with a nearly full voltage of 3.3V at 23 deg C ambient.

2)Over time, whether in use or not, the charge will normally leak, and so the voltage will drop slowly.

3)When in use, the charge will drain faster per design, and so do the voltage.

4)Upon reaching a certain charge level, the voltage will start to drop ‘disproportionately’, each time the signal is advertised. This signifies the battery is getting near to end-of-life, and the electronic circuit needs at least 2.6V-2.7V to function. (You may experience this disproportional phenomena in your phone battery, the first 10% drop seems to take quite long, and thence, it goes to 50% before you have your lunch! Yaak!)

5)When exposed to cold temperature, the voltage will exhibit a lower level, even the charge level is maintained! Users will see 1-2 bars, though the battery is still new, within a couple of months.

6)The battery will still work, even if it is showing 1 bar. However, it will stop functioning at lower than -40 deg C/F. This doesn’t mean it’s dead, and it will come alive again when it’s warmer. (This explains the camera flash issue.)

7)Please do not change the battery, if it’s still new, as long as you are still getting signal. Wait till the winter is over, and it will show the correct voltage again.

8)As you can see, the battery will work between 2.7V to 3.3V, having a working band of 0.6V, over 4 bars. We programmed each bar to show a drop of 0.15V, and this is very very sensitive. This will explain why the batteries read differently esp during the winter. Also take note, not all batteries leave the factories at the same voltage, some were already 3.0-3.1V when we received them at our factory. This is normal for all batteries. This is why we are giving a spare set of battery as a goodwill for all new purchase.

9)We can ship batteries together with a box of sensors, as part of the inherent component. We cannot ship batteries separately, as we need to declare them as dangerous cargo, and it will cost a bomb. You can get them in most electronic stores, and any brand will do. Model is CR-2032, which is a standard description of the battery size.