I have a iPhone 4s, the last version of 17" macbook pro, mac mini 4.1 purchased in early 2010 I think, with multiple trackpads and multiple Apple BT keyboards.
When using a keyboard with the 4s (which I know is BT 4) my keyboard battery lasts for months, the same with my macbook using external keyboard and trackpad (I thought my macbook was BT v2.xx but cannot find the product page for some reason), my mini (which I use most often) the batteries last about a month or less.
From system report My minis BT firmware is v41 c822, the macbook is v41 c821, not really my main question but have these machines been upgraded to BT 4 via firmware update?
So now to my real question, when looking for BT devices how does one know if the device will take advantage of BT 4s' low energy features.