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.

First; I am suspicious of the mAh claim.It works well and holds a charge. I use my 9v powered multimeter quite frequently and got tired of looking for new batteries and borrowing them from smoke detectors. A terrible place to take them from when working with electronics but I had to do *something* to keep working...then I saw this. Now I never have to worry about scrounging around for batteries and it's easy to charge when I'm finished using it.

These have been working fine with my IR lights for ghost hunting. Ran fine for a few hours and still had some juice left. I may end up getting more of these because of how they charge. Very happy with purchase. As with any battery, if it sits for a very long time, they will eventually die. So make sure you use and charge them every so often.

The idea is really nice and I like the product.But it's slightly wider and slightly longer than regular battery.Basically it's plastic case seems to be exactly within the regular battery dimensions, but the transparent plastic heat shrink tube on top of it adds about 0.04"/1mm to width and height.I did read other comments about the dimensions before purchasing, but did not pay attention to it. Well, I still like it, but the size really matters. It turned out not to be as universal as I expected. I still buy regular batteries in addition to these.

Great battery, I use it to light up some lights and I’ve left it on by accident over night and it was still running the next morning. It’s worth the purchase. Just make sure you have a cable to charge it. It does not come with one. I used my PS4 controller cable to charge it.

It was working fine for a few cycles, charging up to the full 9V. However a couple months later it will charge up to 8.2V and not go any higher. When this happens the light on the battery is green so it thinks that it is fully charged.

I needed a good battery option for my TENS unit and this is perfect. It’s basically the cost of a couple batteries but will last MUCH longer. It recharged quickly and holds a charge as long as a normal battery lasts.