I do NOT recommend. They work ok but i had 2 NEW ones that stopped working and their customer support was HORRIBLE.
Does anyone know if the add-on camera comes with a battery as well?
Yes, the add-on has the camera battery.
I have remote properties in two states and have the Arlo Pro2 six camera system (mothership purchase) on both homes. Cannot say enough good things about the Pro 2s and the customer service. Nothing moves on either property without me knowing about it. The videos of the wildlife …
, 
, 
, 
, etc, are amazing! This is a great deal for the Arlo Pros (!), but I prefer the better resolution (1080p) of the Pro2s.