ULTRA LIFE, 10 year, smoke alarm battery, U9VL-X

They were as advertised,

I had one of these in a smoke detector that was over 10 feet high.It lasted closer to 12 years. Works so much better than other lithium batteriesBought this new one to go with a new smoke detector.No need to bring a 10 foot ladder into my house every 6 months.5 star product.

These batteries have lasted a long time so far and no annoying smoke detector beeps. My dog thanks you.

I was so excited to find this battery for my fire detector that was supposed to last 10 years because I have very high ceilings. I bought and installed it last September and my fire detector starting chirping in May. It didn’t even last a year. Very disappointed because one single battery costs $20. Better off buying. normal pack of batteries as they last longer and are much cheaper.

These batteries for smoke detectors are the real deal

Our house has smoke detectors that cannot be reached by a tall person standing on the top wrung of an 8 ft step ladder. Unless one has the fine balance of a circus acrobat, the risk posed by changing a battery annually is probably greater than the risk of dying in a fire. So it just doesn't make sense to use the cheapest 9V batteries in such smoke detectors.Four years ago we installed six of these batteries in smoke detectors, and none has worn out to the point of causing the detector to chirp. That's a good start. We recently had reason to change out one of the batteries installed in a 17 ft ceiling, and the electrician told us that the 10 year battery was getting close to being worn out. So we have come to expect four to five years of life out of these batteries, not ten years as the marketing language suggests. If one compares these on just the basis of the cost of batteries, they may seem a little costly. But if one has to hire an electrician with a 12 ft step ladder every time one smoke detector beeps, they can be a genuine cost-saver.For people with smoke detectors in tough-to-reach places, for people who hate to be woken up at 3:00 AM thanks to a chirping smoke detector, and for people who have a lot of smoke detectors to worry about, these batteries can provide good value. For those who have two or three easy-to reach smoke detectors and who don't mind swapping out batteries every year when the smoke detectors start waking people up at night, they may not be.

Product misrepresented for a 10 year life,normally referring to the SERVICE life.Instead the package is clearly labeled 10 SHELF Life.

As replacing the old battery with this still doesn't make the test pass, I am reasonably certain the alarm itself has failed.Will have to have the landlord replace the old alarm.