Do not stand the cold

I ordered several of these switches has built and switches without son; I used them anymore.
The bateries are buttons and batteries last winter with cold batteries did not give enough of that Current to operate the transmitter. In an unheated toilet (home renovations) can not light the lamp. Keep hold of the switch for the heated and sometimes it works. I did not pay attention to it when buying because I have the other with a 12 V battery and there is no problem.