Robert,

I was wondering how long it would take for someone to ask this question!

I was thinking that myself. Though even if I do leave them in the smoke detectors a bit longer, I would want to pull them at no less than 1/2 the usable power remaining. Still could be used for flashlights.

I wonder if there is a timer in the smoke detectors because when I do not replace the batteries at 6 months, they start tweeting at me. When I pull the battery and test it, it shows full or nearly full charge.

Craig T.