Review on 5-Pack EBL 9V Rechargeable Lithium Ion Batteries With 600MAh Capacity And 5-Bay Charger For Smoke Alarm Detectors - 2A Input by Chris Willis

I purchased this in August 2019. I use the batteries for smoke detectors throughout my house, alarm clock power supply backups, and a guitar distortion pedal. The batteries have been reliable and the charger works just fine. Some reviews discuss measuring the battery terminal voltage and how it's not 9V. Firstly, measuring battery terminal voltage when it's under load is more meaningful. Secondly, complaints about it not being 9V betrays an ignorance of the different battery chemistries. It's possible that there are some applications for which these batteries are not suitable, but I would expect such devices to note the compatible battery chemistries in the user manual. And some devices have a user setting to specify the type of battery being used. Don't blindly buy a product, do your due diligence.