Ok I have had my arduino for absolutely ages and never really done anything with it (mainly because my first objective was far to complicated involving an unknown LCD screen!). So now I have decided to embark on a small project which I can do using someones basic coding for temperature measurement and data logging.
Going forward the unit will become autonomous writing its data to SD card, but then I thought how long will it last on batteries?
Its at this point I should be specific and say what batteries I am planning on using, I have some Ni-CD D cells from some emergency lighting(13-14w compact fluorescent) which wouldnt hold up the lights for quite 3 hours (more like 2.7 which is still a fair amount of time) The pack is 5 Cells giving 6V 4ah.
I know most people run arduinos off AA batts or similar so I wondered how much life span I might get out of these big Ni-Cd D cell packs?
Long term I will look to add a little solar cell to keep things topped up, but for now I want to be able to just run it off a pack I can charge up, providing it lasts long enough.