Talentcell 9V Lithium ion Battery, High Capacity 500mAh Rechargeable Li-ion Polymer Battery with Micro USB Charging Port, 1-Pack

I bought this 9-volt-compatible battery for my digital multimeter voltage tester because typical alkaline 9v batteries have become ridiculously priced and just don't last very long and it's especially frustrating when I accidentally leave my meter turned on.It's micro-usb rechargeable and the bottom of the battery lights up red when it's charging, and lights up green when it's done charging. It contains a 7.4 volt lithium battery (like a small cellphone battery) inside so it doesn't actually reach a true 9 volts. But it should charge up to around 8.4 volts and hang out around 7.4 volts for most of its charge life. Many applications should be fine with this, but I would test your device on a bench power supply first if you're not sure.It'd be cool if they added a voltage step-up circuit to make it produce actual 9 volts, but then it'd probably take up precious battery space and have reduced capacity and maybe introduce high frequency ripple that affects microphones and other audio equipment.Yeah, I'm an electronics geek. Hope all of this helps. I'll post an update if this battery disappoints me in the next couple of years.

I received this on Nov. 14, 2020. I put it in a smoke detector that day. It is now April 17, 2021. The smoke detector just started doing its low-power beeping yesterday. I just recharged it for the 1st time yesterday! So it lasted 5 months on 1 charge, which is pretty darn good. It recharged using the micro-USB port in about 3 hours.The micro-USB recharging port is AWESOME! It is SO EASY to recharge them. The bottom glows red when charging, and turns green when it's done. EASY! No need to find a special charger. Just plug it in and you're good-to-go in about 3 hours. Probably close to the best $5 I've ever spent. Not completely sure if/when I will break-even compared to buying 5 cheap 9v batteries from Dollar Tree. But it's nice to have a rechargeable battery that charges so fast and easily.It is also VERY NICE that you only have to buy 1 battery. You don't have to spend $20 on 4 of them. Unless you use a lot of 9v, it's hard to justify spending $20 on 4 of them. Also, a 4-pack of Duracell 9v disposable alkaline batteries costs $14 on Amazon ($3.50/ea). So if this battery lasts longer than 2 of them, then you're ahead. You can buy generic alkaline 9v's for as little as $1 that last nearly as long as a Duracell. However, it is nice not to have to search for a new disposable one in a box you put somewhere. Just find a USB to micro-USB cable (which you should already have, or can buy for as little as $1), plug it into any USB port, and you should be ready to go in 3 hours.

Holds a charge well. Works well.Fits inside my Fluke multi-meter (model 79 III). Please note, the battery is slightly fatter (thicker) than a standard 9V battery. If your device has a tight battery compartment, it may not fit.Gets 4 stars because everything should be shipping with USB-C.

I have a gas detector that runs on power and uses a 9v for batter backup. Unfortunately, where we have the unit can be bumped and will fall off the wall once a blue moon. It won't announce it's on battery until the batter is low, and it doesn't take more than half a day to kill the battery. I bought this rechargeable battery so that if it happens to drain, I'm not out a battery. It's already paid for itself.

I charged this battery for about 4 hours after I received it. I unplugged it when the internal charging light turned green. The next morning I checked it again. It took another hour to bring it back up to full charge. It appears that every 4-8 hours it requires more charging to bring it back up to full charge. Maybe I received a dud?

I bought this battery for my TENS unit, and it fits fine - it is within the standards for a 9v battery size (the standard is pretty generous...). I love that it does not need a separate charger, and lights to tell when it is charging/done. Seems to work fine. Can't speak to its longevity yet, though.

This battery did NOT fit in my Shure wireless in ear monitor receiver pack. I have had this equipment for 4 years, and have never had an issue with (multiple brands of) batteries NOT FITTING INSIDE.In fact, it scraped a small serial sticker inside that I had to peel off just to fit the old battery inside. This battery caused damage.DO NOT RECOMMEND THIS BATTERY.I will be asking for a refund on this.Aside from the unnecessary and difficult packaging on the case AND the battery itself, they seemed to charge easily and quickly. Won't do much good if I can fit it in the gear.

Best battery you can buy, purchased this back in 2019 and still working after 3years