I have been rather surprised when I found out that my car battery pi died after about 3 days with raspberry pi running.
A bit of a disappointment since my projects is no go until power issue is figured out, but what options do I have?

I assume that average idle power consumtion of raspberry pi and all of it's accessories (HSPA+ modem, wifi sleep mode, gps, bluetooth) will be 2 amps at most which is 24W.
With 64 amp hour rated battery I will get around 12 hours before battery dies. Not sure what to think of my project now.