Thermometer battery life?

Just curious, do you guys leave your thermometers on all of the time or just turn them on to check temps? I have a couple of those flukers dual digital thermometers.

How long does the battery last?

Thanks

I bought a bunch of these for each of my enclosures. I am not to happy with them. The battery does'nt last long. For some reason the accurites last longer. I'm in the process of switching all my Flukers back to accurites.

I have indoor/outdoor digitals from wal mart. The only one I have a battery problem with is the one in my 41 qt blanket box rack. The thermometer is laying inside on the cool side because it has a humidty gauge. The problem is the female tends to lay on top of it and the light is always turning on so it kills the battery. But it's still somewhat readable and has been in there almost a year.