How can I tell whether or not a doorbell 2 is currently charging its battery?

I’ve checked my wiring on my Doorbell 2, and I have good voltage to the terminals on the back of the unit. Unfortunately, batteries discharge continuously over the week, and I have to recharge the battery manually, including the two batteries that I just purchased. Is there any indicator in the app, the battery, or the doorbell that indicates whether or not the voltage is making it to the battery itself? I.e. - is it actively charging?