4-Packs 9V Rechargeable Batteries+Storage Box,1300mAh USB 9 Volt Lithium Batteries 2 in 1 Charging Cable Long Lasting 9 Volt Battery for Smoke Alarms, Multimeters, Microphones,Toys,Guitar

Arrived in 2 Plastic boxes that have room to store the charging cable. 1st charge in a couple of hours. I use them in a voltmeter, stud finder, and various tools. The documentation says to charge them every 3 mos or so to maintain good battery health, so I just set a calendar reminder to recharge them. I've only had them for one week, but they are working as they should at this time.

I got these batteries for my metal detector man they work good they last forever

I cannot address Longevity, as these have only been in service for a few months. They ought to last years, but I don't know that's the case.I fully charged several of these batteries using the included cord. Normal.Output voltage was amazingly consistent during discharge, staying within about 20 millivolts (20 mV) of the nominal 9.00 Volts.in my tests, I discharged them at controlled discharge rates, monitoring them to learn how much energy they deliver. As expected, the higher the current, the less total energy was delivered. At high drain rates, around 50 mA, they delivered about 270 mAh during a five-hour time apan. Later, after recharge and tested at 1 mA drain, they delivered about 425 mAh. That test took 17 days to complete.While the advertised rating of 1300 mAh was not reached in my bench tests of individual batteries, the numbers I obtained are reasonably close to the advertised energy for a single Duracell 9 Volt battery, whose value is given as 500 mAh. These batteries are rechargeable many times; the Duracell isn't rechargeable. Using all four batteries one after another should give you the 1300 mAh of energy -- just not all at once from only one battery.I call it a good buy!

Perfect for my home smoke and CO2 detectors.

Works great

The on-line Amazon description for this battery says that it is "long lasting" and that it is suitable for "smoke detectors". That is just not true. Take a look at the photo I made of the included instructions which state "to preserve battery lifes (sic), use and recharge at lease (sic) every three months."Having to recharge these batterie at least every three months is the antithesis of "long lasting". And that fact makes them utterly unsuitable for use in a smoke detector.My smoke detectors need a rather long ladder to access most of them (as many are located at least 12 feet above floor level). The last thing I want to do it is have to recharge a battery in each smoke detector on a three month schedule (making multiple trips up and down a long ladder). I can purchase non-rechargeable batteries that last 3 or 4 years. A battery that is good for just 3 month is just plain useless.Another thing ... something that they don't mention. I could only make these batteries successfully take a charge by using the included USB-A to USB-C cable. These batteries will not charge or will not fully charge using other USB-C cables (I tried several). So if you buy these batteries, you will need to know where to find that proprietary cable each time you recharge these batteries. Its a small cable ... less that a foot long. It would probably make a great cat toy.And still another thing they don't tell you about in the on-line description ... see the photo again ... you are warned against leaving these batteries charging for a "long time". Well, the chargers I have for my AA and AAA batteries have intelligent charging circuitry which allows the batteries to stay on the charger for weeks or months. That is not the case with these batteries. So that easy to loose proprietary charging cable cannot simply remain connected to a pair of these batteries full time (to keep from losing that stupid cable).These batteries are worthless and they are going back to Amazon.

Good

I use these on a daily basis in wireless audio devices. They last for over 4hrs in my wireless monitor receiver. Definitely worth it instead of buying 9v batteries every day or 2.