thermostat always show low battery
 

I went through my house and changed all of the batteries in all of the thermostats and some of them are already showing a low battery message and the heater doesn't seem to be working. If I take out the battery pack and immediately put it back in it acts like its working for a few minutes but eventually goes back to reading low battery. Any ideas?

Try another new battery?

The thermostat is pulling excessive current from the batteries and that lowers the battery voltage and so gives you a false "low batt" reading?

Check the current draw from the installed batteries with a multimeter or
have the batteries that read low checked in a hardware store or drug store battery checker.

What kind of battery are you using? Rechargeable by chance?

Duracell non rechargeable, I buy them by the case and have used batteries from cases purchased months apart.

I don't have a multimeter and I have never seen a battery tester. I guess I'll have to call around.

Here's one version of a tester
http://www.google.com/imgres?q=%22battery+tester%22&um=1&hl=en&safe=off& client=safari&sa=N&tbo=d&rls=en&biw=1039&bih=765&t bm=isch&tbnid=NGbpV1ZfirwA0M:&imgrefurl=http://www.gd-wholesale.com/chinaproduct/mf63d/av3009to1bv/analog-type-battery-tester-m135254.html&docid=In9WdTm2o6XvGM&imgurl=http://www.gd-wholesale.com/userimg/63/3009i1/analog-type-battery-tester-669.jpg&w=400&h=400&ei=3F6cULbdC4ea0QGyp4GgCg&zoom =1&iact=hc&vpx=775&vpy=185&dur=976&hovh=225&hovw=2 25&tx=154&ty=105&sig=102793154617015424895&page=1& tbnh=148&tbnw=133&start=0&ndsp=25&ved=1t:429,r:18, s:0,i:155

Could also be corrosion on the battery terminals in the 'stat, causing high resistance.