Finally got a successful time lapse using the LiFePO4wered/Pi! It's not perfect, but pretty nice for a first attempt. The funniest thing is that my timing was off on the wake-up timer, so the time lapse runs through the night. Oh well, that's pretty cool too. :)
The system took 99 pictures over about a day, on a single charge! I'm very happy with the result! It was done using the 3.2V LiFePO4wered/Pi version.
And all it took was this little script, called from /etc/rc.local :
#!/bin/sh /usr/bin/raspistill -o /home/pi/Projects/timelapse/`date -Iseconds`.jpg -t 3500 -ex backlight -awb horizon /usr/local/bin/lifepo4wered-cli set WAKE_TIME 9 /sbin/shutdown -h now
The call to raspistill takes the picture. The date tool is used to generate a unique name for each picture. Playing with the raspistill parameters can likely improve the quality of the time lapse.
After that, the lifepo4wered-cli tool is called to set the wake-up timer. Then the system is shut down.
As mentioned before, the wakeup timer is not very accurate and varies from chip to chip. On my prototype, the WAKE_TIME value of 9 resulted in a picture about every 15 minutes.