Keyboard and Trackpad automatically go to sleep?

I think they sleep (in terms of the bluetooth connection) all on their own. I don't use a wireless keyboard, but in my experience my trackpad lasts about a month, using rechargeables. And I strongly recommend rechargeables!

 

How long the battery lasts depends on your amount of use. If I remember correctly, I only had to change batteries once a month on my old iMac's magic mouse and keyboard.

 

I don't use my BT keyboard as much as some so I only change the batteries once every 6-8 months or so. I do use it everyday, I just use it very little, mostly to type in a TV show name or use the arrow keys in iTunes. I bought a Magic Trackpad last night to go with this MacBook which is a 2008 black MB.

My BT keyboard was bought in 2008.