One of the banes of our existance is the false reporting of battery levels by many GPS bike computers. Simply, voltage fluctuates under load and the ANT+ message of low battery may reflect that fluctuation, but it does not correct when the level returns to normal. This leads to many riders changing batteries much too early. Your InfoCrank® will run with voltage per crank down as low as 2.7v and report accurate numbers. Below 2.6v the results are more problematic and it is time to change.
The PC/MAC/Linux firmware updater app available from www.vervecycling.com has a front page that essentially is a line by line check of your crank. It shows details of all the important parameters including battery strength. You do NOT need to do an update using the programme, but you can easily check the battery level. It will tell you also if the batteries are dangerously low and if they are finished, it will not find the crank.
The Android apps - VINC and Firmware updater - also show in simpler form the state of your InfoCrank. These are available from the Google Play Store - search for infocrank. Also upload the ANT Tester so that it can check your device to see if you need to upload any drivers, though most Androids have ANT installed.
VINC does a test when the cranks are paired and shows the crank number, length, battery level and firmware level. Once again, easy to see if your batteries really need replacing. Android Firmware updater is designed for total simplicity and just does it checks and tells you whether the cranks have enough charge to do an update. Clue...if they have enough charge for an update, they have plenty for reading your InfoCrank®
Remember to replace both batteries in a crank when the level gets too low. Right cranks often use more battery than the left because they transmit to the left crank - and the bike frame is not a conductor and the messaging is difficult - while the left crank transmits to your bike computer, which is relatively easy. That is also why they are harder to "find" by the apps and the bike computer.