Hi. First post here, please be gentle!
Having recently discovered the Arduino, I've set about my first project - a fairly simple dual battery voltage monitor and indoor/outdoor temperature gauge for my campervan. My knowledge of electronics is basic at best, but I know my way around a page full of code and I've made surprisingly quick progress so far.
My question is about building a voltage divider, to drop the 12v battery down to a range the Arduino can cope with on its analogue inputs. I completely understand the principle, but am concerned about the consequences of bridging the positive to negative terminal on a 110Ah battery with a couple of tiny resistors like suggested on this page and other tutorials I've read.
Is this safe? Won't the resistors melt with all that power? Do I need special resistors?
If it is safe, how much power will be drawn from the battery by the voltage divider?