The Fob has a long-term battery life but it does occasionally need to be charged using the micro-USB cable that shipped with it, or a similar cable.

How often does it need to be charged?  

You can expect it to maintain a charge for at least 400 transactions before it needs a charge. For the average user, this is approximately two months.

How do I know if my Fob needs a charge?

No LED light when you push the button is a good indication!

How long does it need to charge?

Usually 40 minutes.    It's fully charged when the LED is solid green. Flashing green means charging is still in process.