Rechargeable 9v Batteries USB 9 Volt Battery for Smoke Alarms 3700 mWh 9v Lithium Battery with 2-in-1 USB-C Charging Cable and LED Charge Indicator, 2-Pack

Works great in a metal detector that takes two 9V batteries. Also works great in an Ethernet/phone line tester. Easily recharge. Lighted notification of when the battery is fully charged. Definitely worth buying vs buying 9V batteries every time you need a new one. They also weigh a lot less than traditional 9V.

They hold a charge for a long time and it doesn't take long to recharge

3 batteries worked great, one was DOA after one use..... Will not recharge. Plan to call company next week

So far so good. Recharges fast, works fine. They are lighter than I thought they would be. They seem as tough or tougher than a regular 9v, despite being plastic. I looked at a lot of rechargeable 9v batteries since I couldn’t find a single one that was a “name brand” and these have met my expectations so far. I’m happy with my choice.

Great price for these powerful. Huge storage batteries? They're working well in my safe and seem to be very. It's strong and well built

These are perfect! I need to change my 9-Volt batteries quite regularly and with these I'm saving a lot of money. I just take them out and recharge them. It is very nice that they charge using USB-C since I have a lot of USB-C chargers. However, it came with it's own USB-A to dual USB-C cable! How nice is that! Battery life has been great so far and it works just like a regular 9-Volt battery. I wish I bought it sooner!

Decided to give these a try for a lifepod safe since that's about the only thing we have that uses 9v batteries. We have two of the lifepods and replaced the regular 9v batteries that were in them for about the last 2yrs. The standard 9v batteries were pretty much dead however they had enough juice left to enter the code one more time to open the pods one more time. Ordered these in middle of March, charged them up and installed. Have only opened the pods twice since that time so barely any use with the electronic key pad and today 4/29 went to open one of the pods and it was completely dead so had to find the key for it to get in. Decided to check the 2nd pod and completely dead as well as the first. Batteries didn't last 2mo with barely any use so can't recommend these batteries. Maybe just a bad set but the standard 9v random brand name that was in there before lasted over 2yrs without issue and these crapped out in less than 2mo. Not sure why truthfully as most reviews look good but can't risk trusting these if it came down to needing what's inside the lifepods in an emergency.

The item came with a charge but is not compatible with use in a smoke detecter. It would have been helpful if this was disclosed in the product description. For other uses, it probably is fine. In a smoke detecter, the unit acts chirps to indicate the battery needs to be replaced.