Though I did this before the Zero W came out so I had to have that ugly USB hub and WiFi adapter there. Something is being built across the street from me which is what prompted me to set this up.
I used a raspberry pi 2. I was tracking the movement of a plant in my apartment http://imgur.com/a/hoEwO
I used a simple cron job to capture photos in the waking hours of the day and upload to a cloud drive. Was definitely a fun project. I was hoping to eventually expand the project to include image detection so I can keep track of the various animals roaming my apartment. Also, create a mobile app that would allow me to snap pictures or videos remotely, but haven't gotten around to it yet.
And yes, this is one of my favorite Pi projects too; it's one of the few where I can show my wife the results and she doesn't just roll her eyes at me.
How long does the battery last? I'd like a camera at our summer cottage to take a timelapse during the whole winter (in Finland, so snowy), turn itself on each day, take a pic, shut down, repeat for like 6months, not sure it's possible?
I have a similar project for monitoring fruit trees. We use a SleepyPi add on to our pi zero (basically an Arduino with a rtc module) in order to shut down the pi zero during the downtime and save battery. Should be able to run for several months this way.
On my home server/NAS, I use rtcwake to sleep the computer for a few hours, then wake up, check if there's work to do, then sleep again. I'm not sure if it'd work with a Pi, though, since its hardware is different from a typical motherboard.
Alternatively, you could use something like an Arduino, and connect it in some way to an independent camera. Since it doesn't need to process the picture, you don't need a powerful processor or MBs of RAM.
The Raspberry Pi doesn't support power management of any kind. It simply can't go into suspend or soft power-off because it doesn't have the hardware to do it. In theory the C.H.I.P can but I'm not sure if the software support for that feature is there yet.
Something like that is possible, but you'd have to probably build your own battery and power circuitry; most USB power packs shut off after a few minutes without any current draw, and you need to press a physical button to turn them back on.
The AUKEY supply I'm using goes for about 6 days, continuous.
You can also have two packs and judiciously swap them out every week or so. That's my plan for a video I want to record later this year.
https://github.com/bschwind/timelapse-zero
I even have the same carbon fiber case:
http://i.imgur.com/PF5kri7.png
Though I did this before the Zero W came out so I had to have that ugly USB hub and WiFi adapter there. Something is being built across the street from me which is what prompted me to set this up.