Micro USB Charge: BESTON 9-Volt batteries can be charged by any USB 5V output like wall chargers, s, it does not need an extra charger Stable Voltage Platform: Unlike alkaline 9V battery's 9.6V to 5.4V output voltage, lithium ion 9V rechargeable battery has stable 8.4V to 6V discharge voltage platform High Capacity: Our 650mAh 9Volt rechargeable battery has more power capacity than alkaline 9V battery (about 500mAh) Long Life: They can be recharged more than 500 times, make them a economical replcement for primary 9V batteries This battery can only recharge to 8.4V. If your devices like e alarm require standard 9V or higher voltage battery, please buy standard Alkaline 9V Battery