Rechargeable Lithium D Batteries with 4 in 1 USB-C Charge Cable,4 Pack D Cell Li-ion Battries,LR20 1.5V D Size Cell Battery Replacement 7500mWh fo...

They seem to have excellent power, and work well in my 3 c cell flashlight that has a super bright led bulb and can focus the beam. Hi is almost too much for most things, low is usually best. I put the batteries in before charging, and they worked well for over an hour on low. I then took them out and they are re-charging now. I will put them back in, and I expect they will last a long time. if after awhile they fall short of expectations, I will come back and review them differently, but I don't expect that to happen. I like these batteries a lot, and I recommend them. At $5 apiece, they seem expensive, but when you charge them many times at very little additional cost, they become very reasonable!

The media could not be loaded. USB-rechargeable Lithium-ion batteries like these Messule AAs are truly game-changing tech. They rock my world in ways that no other type of battery ever has. Just as an example, with a 1.5-volt output instead of the 1.2 volts of rechargeable NiMH cells, theyve even resurrected an old power-hungry digital camera that I quit using years ago because it ate alkaline AAs so fast and wouldnt even turn on with NiMH batteries. Lithium-ion chemistry and USB-rechargeable technology definitely elevate the small household battery genre to a whole new level with their utility and convenience. The four batteries arrive in a convenient hinged, snap-closed transparent plastic box along with a short hydra-headed cable with a USB-A plug on one end and four USB-C plugs on the other. Plug the A-side into a wall outlet transformer, a laptop or desktop computer, a power bank, a car adapter or any other appropriate power source. Green LEDs near the batteries charging ports flash when theyre charging and go solid when theyre fully charged. They worked perfectly in every device I tested them in, including a wall clock, a TV remote, a weather station temperature sensor, a flashlight and the aforementioned camera. Yes, theyre quite expensive, at (currently) $19.99 for four, or $5.00 apiece. Five bucks for one AA battery? you may exclaim in stunned disbelief. Well, true, but you dont just use them once and throw them away; theyre rechargeable more than 1000 times. Thats a lot of juice for not much juice, if you get my drift. I love these batteries. They work great, they charge conveniently and quickly (supposedly five times faster than traditional AA Li-ions, whatever that means), and they reduce hazardous waste. What more could anyone ask for? I most enthusiastically give them my strongest endorsement and a well-deserved five-star rating.

The build quality of these batteries seems high. The usb-c charging ports are very firm and snappy, able to support the batteries dangling as they charge. This "dangle" (or even just being spread out by the included charging cable) also helps them dissipate heat compared to a cradle-style charger. Though I'm not sure how important that is for modern, lithium batteries, or at what temperature it becomes important. These batteries come with no documentation and no power brick - I see nowhere on the product page that indicates how much fast-charging USB current these can take advantage of. The images on the product page list "2H Quick Charging" while the text on the product page says "With 90-minute fast charging." Because these batteries are reported to hold (collectively) 18 watt-hours of energy, a 2.4 amp (12 watt) charging brick would charge them in 90 minutes, if you disregard any inefficiency factors. Which is to say: the manufacturer should provide better documentation, and if your charging is slow you should check the rating of your USB power brick. Devices that monitor voltage will not be able to estimate remaining battery life due to the design of these batteries. Because they output a (nearly) constant voltage until they die suddenly, most battery meters will interpret them as fully charged until the moment they die. This is the case in my Pentax K-50 (one of the few DSLR cameras that can accept AA batteries with an insert). I lack the equipment to test the 3000 mAh capacity, and I lack the patience to test the claimed 1000+ charge cycles. If these are as claimed (or close), these are good batteries.