Material tracker using GPRS+gps

Hey! :slight_smile:

I'd like to build a tracker for my trailer.
I wanted to use the sim900 gprs to send the position of my trailer (via gps module) when I send an sms.
But the problem is the battery. I need a small system that can be hided in the trailer. So, i can't take a car battery or something like that.

Is it possible to put the sim900 into powersaver? With a arduino pro mini?
I don t want to change my battery every week...

So, if someone has an idea it would be nice!

Thanks a lot!