Keypad batteries die overnight?!?

Has anyone had the problem of getting the "low battery" warning on the keypad overnight? I've never had any problems with my Simplisafe system, but since "upgrading" to a new base station earlier this month (I didn't ask for it...Simplisafe just sent it to me...and there were lots of problems getting it set up), every night that I turn the system on to "home", the next morning, when disarming the system, the keypad tells me "low battery". I've tried 5 different sets of 4 AA rechargeable batteries (charging them all up first) over 5 nights, and keep getting the same message the next morning. If I DON'T turn the alarm to "home", then the batteries seem to last longer (which makes having a security system pointless). I've NEVER had rechargeable batteries last just one night...I think typically, I only get the low battery warning (and recharge the batteries) maybe twice a year? Has anyone had this problem, and if so, do you have any suggestions of how to resolve it?