Hehe, I just find the idea of driving a little microcontroller with a big motor battery weird. Never heard of it (asides from the computer INSIDE an engine). Then again, I'm just a beginner 
Nevertheless, I just checked a little bit. Motorcycle battery dimensions are somewhere around 15 x 7 x 10 cm or something. Still pretty big. Plus they are heavy with ~3 KG or more. These loggers usually hang somewhere on a ceiling in a warehouse or (clean) production corridors. The price of them isn't that bad though... 35 to 100 dollars is ok. Uhm, if you can recharge them after a year that is, instead of throwing away. Well, that should be possible 
But seriously, do all remote Arduino projects use car/tractor/boat battery's? Sorry if I sound silly
Rick