A long time ago upon the advise of a couple ASA regulars I started using nothing but Coppertops for smoke detectors that use 9V batteries. Before that I tried cheap batteries, other brands, and even expensive lithiums. The Coppertops seem to have given me the least trouble over the years. The other day I was making my routine recommendation to a non-client and he jumped all over me that Consumer Reports says except for generic no-names they are all the same.
It wasn't the first thing he jumped on me about of course. As snowbird he had already pointed out to me how so many things were superior where he came from over Arizona. (I had to bite my tongue to keep from telling him to go back there then. I really hope he doesn't call me back to install his system.)
Anyway, its been a long time since I did a timed load test, but back then there was a definite difference in discharge curve between Energizers and Coppertops. The Energizers would maintain a higher voltage and then drop off suddenly. The Coppertops would maintain useable voltage levels for longer but more steadily decrease.
The summary I came to was that devices that can operate effectively on lower voltage levels would benefit from Coppertops (like incandescent bulb flashlights) where as devices that needed a more constant power supply (like charging the discharge caps on a photo flash quickly) would benefit from the use of Energizers.
All that being said, what do you guys use for 9V batteries in smokes? Why?
I don't actually run into it often except in a few wireless systems I have installed, but it does come up when I get the classic, "Your smoke detector is beeping," call from a client who doesn't understand that if there was a problem with an alarm smoke it would show up on the keypad too.