4100mWh Rechargeable Lithium AA Batteries, Variable Voltage 1.5V with Low Power Alarm, 2500+ Cycles for Smart Door Locks, Toys,Flashlights and Game (AA USB-C 8-Pack)

I bought these specifically for my smart door lock, which has been going through standard batteries way too fast. It was becoming a constant expense, so switching to these rechargeable lithium batteries has already been a great move. They provide a steady voltage, which is exactly what a smart lock needs to function properly without those "low battery" warnings you sometimes get with old-school rechargeables. The most convenient part is the built-in USB-C port on each battery. I don’t have to keep track of a separate charging dock; I can just plug them directly into a phone charger using the included cable. So far, they’ve been holding up well and haven’t given me any issues. Being able to recharge them up to 1500 times means I won’t have to buy disposable batteries for a long time.

These USB-C rechargeable AA batteries work great. Easy to charge with the included cable and no separate charger needed. They provide steady 1.5V power and last a long time in my devices. Very convenient and a good replacement for regular batteries. Would buy again

It's well-made, has a large capacity, and charges quickly. It's perfect for use in remote controls, toys, flashlights, and other electronic devices. Even after multiple charge and discharge cycles, the battery life remains stable with no noticeable degradation. It's environmentally friendly and saves money.

It can be charged by using different charger. And it works good for all the devices. The best thing is it won't leak.

They work

These cells do hold more energy than any other cells I have tested, except single use lithium cells. I'll try to include those in my test result, just for fun. Test 1. Constant current (CC) load. 400mA, stop at 0.8V. remGretivon 4100mWh was able to deliver 2586mAh or 3313mWh and took 06:25:05 to do so. Similar 3600mWh was able to deliver 2312mAh or 3203mWh and took 05:46:46 to do so. Standard Alkaline was able to deliver 1667mAh or 1908mWh and took 04:10:05 to do so. Single-use Lithium did not test. Test 2. Constant power (CP) load. 0.48W, stop at 0.8V. remGretivon 4100mWh was able to deliver 2670mAh or 3468mWh and took 07:13:34 to do so. Similar 3600mWh was able to deliver 2220mAh or 3135mWh and took 06:32:00 to do so. Standard Alkaline was able to deliver 1500mAh or 1728mWh and took 03:36:05 to do so. Single-use Lithium was able to deliver 3458mAh or 4688mWh and took 09:46:02 to do so. Test 3. Constant resistance (CR) load. 3.75 ohms, stop at 0.8V. remGretivon 4100mWh was able to deliver 2571mAh or 3354mWh and took 07:27:20 to do so. Similar 3600mWh was able to deliver 2204mAh or 3081mWh and took 05:56:03 to do so. Standard Alkaline was able to deliver 2133mAh or 2433mWh and took 06:54:36 to do so. Single-use Lithium did not test. Test 4. Portable CD player. Volume at max, play full CD on repeat until shutoff. remGretivon 4100mWh played for exactly 47:52:01. Similar 3600mWh played for exactly 44:32:13. Standard Alkaline played for exactly 44:39:30. Single-use Lithium played for exactly 66:06:13. Test 5. My contraption. A mechanical counter geared to a motor. More turns scores more points. remGretivon 4100mWh scored 7744 points and took somewhere around 86:20:15. Similar 3600mWh scored 10071 points and took somewhere around 74:25:12. Standard Alkaline scored 11257 points and took somewhere around 106:24:16. Single-use Lithium scored 12198 points and took somewhere around 100:49:22. Of all these tests, the CD player is probably the most realistic. Since these do really good in that test, I'd say they do indeed store more energy than the 3600mWh cells. I don't claim that my test equipment is super accurately calibrated, so the capacity measurements are as good as I can get them, but probably off by some factor. Even with that, these cells are not made to actually be able to deliver 4100mWh. They drop in voltage as they discharge. That means they have a harder time delivering high mWh values in any of the tests. Personally I think they should have labeled and sold these as 2500mAh cells. I don't like that you cannot charge them with USB-C power delivery chargers. I didn't time how long it takes to charge, but it is less than 4 hours. It's pretty obvious that the statement of "They maintain stable 1.5V output and alert you with an audible alarm before depletion" is a lie. The cells themselves do not make any noise, at least I have not heard any while in the same room for 6 of them completing their tests. And for the "stable 1.5V output" just look at the graph. Conclusion: I'm giving them 4 stars because they do have a lot of capacity for rechargeable cells. The non-sale price for these is competitive. I don't like the false statements in the product description, but I'm not going to dock them hard on this review for them.

Used these rechargeable batteries for my coffee mixer and wireless mouse. It's easy to use as normal batteries and recharge them when they ran out. The fastest charging is super quick.

So far, so good