Reddit reviews Tenergy 9V NIMH Rechargeable Batteries, 200mAh Low Self-Discharge Square Battery for Smoke Alarm/Detector (2 PCS)

LONG LASTING POWER - Tenergy's Centura 9 volt battery for smoke alarms offers the best long term performance. Generate energy savings by switching from standard single-use 9V size batteries to rechargeable batteries.LOW SELF DISCHARGE - These 9 volt size battery experience significantly low power loss when properly stored and unused. Unlike typical NiMH batteries, Centura low self-discharge 9V battery can retain up to 85% of capacity even if stored for 1 year!EXTENDED CYCLE LIFE - Rechargeable up to 2,100 times without significant capacity lost. Tenergy's Centura rechargeable 9V batteries will work like new even after a year of daily usage.ECO-FRIENDLY & MONEY SAVING - Being one of the most cost-effective batteries, the Tenergy rechargeable NiMH 9V battery pays for themselves after 10 cycles. Avoid wasting time and money on the disposable alkaline batteries and replace them with our rechargeable Centura Rechargeable 9V Battery to decrease the waste disposables leave behind.PRECHARGED READY-TO-GO - Use these rechargeable NiMH 9V batteries when first received, or fully recharge them for the best experience. Purchase with confidence, these batteries are UL certified for safety and include 12 months warranty.