Review: FirstPower 2pack 6040mAh ring replacement batteries with charger

Amazon Affiliate Link: https://amzn.to/4sltmcx FirstPower 2-Pack Replacement Battery for Ring Doorbell - 6040mAh Rechargeable Camera Batteries with Charger Station for Ring Video Doorbell 2/3/3 Plus/4, Spotlight Cam, Stick Up Cam and Peephole Cam' These batteries plugged into my Ring Peephole Cam and powered it just fine. I opened one up and capacity tested the two 18650 cells inside. They are marked at 3.1 Ah capacity, and tested at 3.2 Ah, meaning that the 6.040 Ah (6,040 mAh) rating on the batteries is accurate. The charger works with a USB-C cable (they include an A to C cable, or you can power it will a power delivery cell phone charger, as it successfully negotiates USB-C power delivery) but only draws 5 volts at 2 amps max. (It will take around 5-6 hours to charge a fully discharged battery.) The charger can charge Ring OEM batteries, but I found that the dimensions were just a tiny bit larger than the batteries that came with the charger, so it takes a lot of force to insert/remove the Ring OEM batteries. [The FirstPower batteries slide into the charger easily, and also worked just fine in my Ring device...] So overall the batteries meet their power specification, the internal construction looks good with a proper BMS and charging circuit, and they run ring devices correctly. The charger fits the included batteries, but is just a little tight on OEM batteries, although it does successfully charge them.