How long does the battery in the exerspy armband last?

Answer:  The average life of the lithium ion battery used in the exerspy armband is roughly 500 charge cycles.  A charge cycle is defined as the time it takes to charge a battery from 0% to 100%.  As the 500th charge cycle is neared, the battery’s overall performance may drop to around 80% efficiency. However, this can be greater or less depending on the day-to-day operating conditions of the battery.

Other factors can affect battery life, such as leaving a device exposed to extreme conditions (leaving the armband in a car on a hot day) or storing the device for extended periods of time with no use, during which time the battery is fully discharged.

Therefore, ‘topping off’ as much as possible is better for the battery than completely draining the battery and charging.  This holds true for any product that uses a Lithium Ion Battery (cell phone, laptop battery, mp3 player, GPS device, etc.)