Amiable Upgraded 5V 5000mAh Li-Polymer Rechargeable Batteries, Suitable for Heated Gloves Heated Scarf Heated Socks, Heated Slippers Spare Battery (Black)

Great

Used them once and they didn't work the next time I tried to use them. Apparently, you need to continue charging them - even when you're not using them. I hadn't charged them in three months and they wouldn't charge. I guess it's my fault for not keeping them on a charging schedule. I never heard of anything so stupid. Rather than buying these, I'd suggest you burn your money and use that fire to warm you. You'll be warm and less frustrated.

These do not work with the app, and they were hard to adjust the temp.

Update: dropping to two stars. These held a charge for a surprisingly long time. I was able to do my daily dog walks for a few weeks before they finally ran out of battery. As noted below, they were a slightly lower output than my gloves call for, and they didn't seem to get them as warm, but it was enough to keep the chill off. Unfortunately, when they finally ran down, I tried to recharge them, but they wouldn't take a charge. So now they're just toxic junk that I need to dispose of responsibly. I still have use for the two headed USB-C charger, though, so that's kind of nice.My original review:I have Snow Deer heated gloves, and before that I had Vasion and Volt gloves. All three use 7 or 7.4 volt lithium-ion batteries. I decided to try these as a replacement battery, since my old batteries have started to wear out. They don't hold a charge long. Having done a little research, it appears that lithium-polymer batteries (like this model) are not considered as good as lithium-ion, so I'm not sure this will be a better replacement, but so far so good. There are a few features here that I prefer to the old ones:I like that they're chargeable using a standard USB-C cable. They come with a 2-headed cable so you can charge both at once, but if you misplace that, you can just use any USB-C charger. The other batteries require a specific charger that I have to keep track of and can't use for anything else.I also like that these batteries have indicator lights to tell you when they're fully charged, or to view their current charge level. My other batteries are a black box, so to speak. I know they're running out when the power button on my gloves starts to flash, or when they just turn off. And I know when they're fully charged when the indicator light on the charger changes from red to green, but there's nothing on the battery to indicate its charge level. They also strangely have what looks like a red power button, but that appears to be decorative. It doesn't do anything.These are slightly larger than the older batteries (comparison picture attached). But they fit my gloves, and they're actually slightly lighter than the smaller batteries (6 grams instead of 7).Perhaps the most important difference is that these output 5 volts, rather than 7 or 7.4, like my older batteries. They still seem to work in my gloves, but my gloves think they're running out of power, so the on/off button on the gloves flashes while they're in use. Slightly annoying, but not a big deal, and they do heat the gloves.

These do not work in my heated coat or my heated socks and you cannot use them for battery banks so they are useless to me.