The bottom line: NO.  Snopes.com has all the info. Some web pages say it can increase battery life by 3% over 5 years but is not worth the hassle because when you need a battery, it won't work until it's room temp. My bag of 9v, AA and various other batteries are in the closet now....ready to use and not hiding frozen hamburger I will discover freezer burned later and throw away.  You're welcome and thanks for visiting KORD's website.  We do lots of informational and fun stuff here every day!