USB 9V Rechargeable Battery- 9 Volt High Capacity 650mAh Square Lithium Batteries with Type C Port Cable for Smoke Alarm Detector,Wireless Microphones & More (2-Pack)

Is short time but work ok in the sensors

I bought them for my smoke detectors and they work fantastic

Poor quality. Self discharge. Do not buy. I bought two of these so I could swap them out of my device while the other one charges. I charged them both up. They self discharge over time so that when the one in my device dies the other one is dead too. Why bother?

Works good. I try to use rechargeable batteries as much as I can, to be environmentally conscious. It has a 2 cable charger so both can be charged at the same time. Cannot find rechargeable 9-volt batteries in local stores.

I have several little audio items that run on a standard 9 volt batteries. I was attracted to these rechargeable batteries so I could just charge them with a USB charger and not have to keep buying 9 volt alkaline batteries all of the time. I also liked the little charging port on the batteries, but noticed there were no charge/discharge lights to indicate status. Being an electrical engineer, I measured the voltage on each battery and was happy to see something 9.03 or 9.04 volts, with no load. I assumed they were fully charged already and tried them out in my devices. Nothing. I measured voltage again with my DVM and they both read zero volts. That's odd, first read full voltage, then zero. So I charged them overnight with the a small USB charging device which monitors both output voltage to the batteries and current. Voltage was OK on the charger but the current was zero, which meant the new batteries were not taking a charge. Only when I connected the new batteries to a larger battery pack designed to be a portable charging device for traveling, did both the new batteries take a charge and work when placed in the devices. Bottom line... The batteries are shipped with no charge, but may measure a full scale voltage on a DVM. Huh? If they had battery status lights, like stated in the Amazon ad, I probably could have avoided all of the BS I did at first. I gave this review 4 stars because of the confusion I had at first. I assume these batteries will last much longer that a typical alkaline battery, but that remains to b seen as time goes on.

I thought that one of the two batteries was defective. After further investigation, I found the charge cable was defective on one side. I had plenty of usb c cables so I canceled the return request. I gave it only 3 ⭐️ due to defective charger.

I bought these for my smoke detectors, recharge them when time changes.

Good batteries. I charged them, they are powering my devices.