I tried rechargeable (NiCd and NiMH) batteries and they were basically unusable. The voltage from them at full charge (~1.25-1.3 V) is not high enough to have any usable life. The so-called 9V replacements actually only run about 7.8V at full charge. Using four GOOD NiCd AA cells in a camera gave me maybe 2 or 3 shots. I sure as hell wouldn't rely on them for a smoke or CO detector. Use a GOOD quality Alkaline battery or cell and be SURE that they will do the job you need done; at least 6 months in a CO detector. Change them at DST and standard time changeovers. For cameras, use the Lithium AA (or AAA) cells for best life. Consumers Reports recently published a recommended list of the Lithium-Ion cells and Eveready checked out tops. Check it out at your local library if you are not a subscriber. * * * * * * * * * * * * * ** D C "Mac" Macdonald ** * Grand Lake & OKC - OK * ** AGLCA (#217) & USPS ** ** USAF & FAA, Retired ** ** Amateur Radio K2GKK ** * * * * * * * * * * * * * > Date: Sat, 14 Jan 2012 10:56:11 -0800 > From: circumnavigate06@bellsouth.net > To: great-loop@lists.trawlering.com > Subject: GL: small batteries > > Fellows, > Many of my devices/toys use small batteries, like AA, AAA, 9v. Does anybody > know where to find valid information on what is considered a full charge & an > empty/time to replace charge for these batteries? We have smoke alarms and > carbon monoxide monitors that I want to be sure do not go unattended. > Thanks, > Tommy