VARTA Lithium 9V Block 6LR61 Batteries (1-pack) - ideal for digital cameras, toys, GPS devices, sporting and outdoor applications

This is an excellent battery, expiry 2031 !

After reading all the reviews, one reviewer pointed out that most alarms report a low battery at about 9.2 volts. This is based on the discharge functions for alkaline batteries. My Lithium battery in a smoke detector alarms at 8.8V and works well with Lithium batteries. These batteries do not list smoke detectors as suitable applications. Modern alarms may have too high a low battery alarm threshold.My new CO detector specifically says NO LITHIUM BATTERIES.Possible solutions:Replace alarms for ones that that recomend lithium batteries. They should be replaced every 10 years anyway.Use batteries recommended for smoke alarms. Ansmann smoke detector batterieshave a 850 mAh charge but lower than that of a Li metal one. The shelf life is 7 years compared with that of a Li at 10 years.Hixon rechargables also hold 850mAh. Other brands are only 600-650mAh. Do not use rechargable alkaline as they only hold 170-200mAhSome recommend Zinc Chloride batteries at < £2 and about 5 year storage life and 1 to 1.5 Ah capacity. E.g. Panasonic 1148 so it will cost pennies per year for 2-4 years.Li batteries are rated at UP TO (i.e., LESS THAN) 10 years of shelf storage. but will last a much shorter length of time under the current load of a detector. They usually hold 1200mAh so should last much longer than alkaline batteries with their shelf life of as low as 1 year. They might need to be replaced 5 times as often as Li metal.Use Zinc Chloride, 850mAh alkalines or lithium metal batteries in recommended detectors. Good luck.

Bought mine in 2012, and it was still working when I tested just before writing this review!However, these batteries do have an expiry date from the date of production. So if you get an old one, then it won't last as long. So unless the online seller can guarantee that you get a "fresh" battery, it's better to buy it in a physical store so you can confirm the expiry date before buying.

I ordered this in April 2013 for my smoke alarm. Checked my smoke alarm recently. Still OK, but I noticed best before date not marked. Its a mains smoke alarm so its only "shelf-life" which is important. Having to replace based on 7 year shelf life stated in product description. Would have preferred a date stamped on battery. Disappointing for a "professional" product. Going to replace it with another brand.

dont know yet have to wait and see how long it will last it is being used out side so we will see