Some of the plans I've seen say they are able to log the current ambient temperature and notice any increase in it...
In other words if your banks temp is 75 degrees at the start of charging, the switch can cut off the charger when it senses a rise in that temperature. Same thing if it's 30 degrees, it just senses the increase in temp.
I really think I'm going for the circuit that monitors voltage rise and when it starts dropping it shuts the charge off, some of these circuits use the temp switch too as a fail safe backup.
About the dog lite, when I leave for the night and won't be back until after dark is when I use the light, he sleeps in the dark OK but I don't want him sitting around alone in the dark when I'm not home and burning a 40 or 60 watt bulb should be against the law for that reason :-)
I stuck a few cells to the basement window where they can't be seen then wired up through the floor and wall to where I want the light..works great. Think about doing more with it too, like under kitchen cabinets and behind some crown molding in one bathroom that has no window.
It's been alot of fun messing with this, and it hasn't taken a huge investment to get excellent results either.