4 Pack Rechargeable 10440 Batteries, Lithium 10440 Batteries?Not AAA Batteries? Rechargeable Lithium Ion 3.7 Volts 10440 Battery with 4 in 1 USB T...

The pros: Easy to charge, and with the split cord that can charge all 4 batteries at once. It's pretty convenient. The cons: The charging ports on the batteries are cheaply made. They aren't straight, and you have to be careful to not break them when charging them. All in all, for the price I paid they're worth it. Even if they only last for 10 charges, you still save money.

I found a 4 D cell battery flashlight in the garage. The batteries were dead, but it was nice and clean. Decided to upgrade it, switched it to Lithium rechargeables and replaced the old incandescent bulb with a LED. Works great, nice and bright, lighter too... Batteries can recharge in about 2 hours. It was nice to repurpose an old flashlight and bring it into the 21 century...

These are EXACTLY the same as "Lankoo USB D Lithium ion Rechargeable Battery, High Capacity 1.5V 12000mWh Rechargeable D Battery, 4 H Fast Charge, 1200 Cycle with Type C Port Cable, Constant Output,2-Pack," or the "VARWANEO Rechargeable D Batteries 2-Pack,Recharge up to 1200 Cycles High Capacity 1.5V/12000mWh, Fast Charging with USB," ZeeBooth also sells. I expected them to be the same batteries, and they are. The design and material construction is EXACTLY the same. Unfortunately this includes the worst designed, cheapest, and most flimsy positive terminal someone could design. Both brands are equally bad. I wasted $30 (3x$10/ea.) on 3 D-cells by both brands (2 of these and 1 of the other) that are useless because the positive terminal either broke-off or crushed/smashed into the battery so deep they can't make contact with the inside of a D-cell Maglite. The two that are crushed were the result of dropping them from 2-3ft while INSIDE a 2xD-Cell Maglite flashlight/torch. The flashlight is fine, not a dent. But the positive terminals are shot, dead, useless, trash! How can that even happen when they were protected by the flashlight which took most of the impact?? And especially for $10/ea! On the positive side, they appear to hold a charge for about 10 months. That's not bad. The 3 that still work, work well 2 years later. The USBC port makes them simple to charge, but they take more like 8-10 hours to charge. I don't know where they came up with "4-hour charge." That's not even close!. They are ALWAYS VERY BRIIGHT in a flashlight/torch. Unfortunately, they DON'T dim before they die. They run until they can't sustain 1.5v and then turn off, instantly. Conclusion: All brands of D-cell "lithium rechargeable" batteries (at least the 12,000 mWh models with a USBC charging port) appear to be the same, just re-badged. They're really not useful for much unless you have a device that uses lots of D size batteries, and frequently. Although a shelf life of 10 month is relatively good for this type of battery, it's not great for a flashlight or other low-drain devices unless you use them A LOT. 10 months may sound like a long shelf life, but trust me, 10 months goes by faster than you think. Another problem with using them in a flashlight is the "instant-off" feature. You get NO notice that they are about to die! It is nice that they are always 1.5v and always very bright in a flashlight, IF they are working. For something like a Maglite flashlight, just buy disposable alkaline batteries that are durable and have a shelf life of 10 years! Otherwise, plan to write on your calendar every 4-6 months "recharge your D-cells" so you don't have to worry about them just turning off unexpectedly, most likely when you need them the most. One last thing, these batteries HARM THE ENVIRONMENT MORE THAN THEY HELP IT!! 3 out of 6 of these batteries (50%, made by 3 different brands, which is a fairly good sample size) didn't even last 6 months before I had to toss them in the trash because of the cheap construction. Not only did I waste $30, it's HORRIBLE FOR THE ENVIRONMENT!!!! The remaining 3 probably have to last about 20 YEARS before they break-even with the waste created if I had just bought 4 alkaline D-cells that last 10 YEARS!

I purchased the four D cell pack for use in my Mr. Heater Big Buddy portable propane heater with fan. The fan ran continuously for 13 hours before I needed to recharge the batteries. I realize the fan is not a high drain device, did not pull a lot of power (mWh) but I was still very pleased.

Was very pleased. Rechargeable batteries (x 2) arrived and I just plugged them n with the USB cable. (You need somewhere to plug in the cable. Charger not included. Batteries charged in under an hour as red flashing light turn solid red. Nice product!