Universal Smart 2 Slots 18650 Battery Charger Set,4 Pack 3400 mah Rechargeable Button Top Batteries Battery for LED Flashlight Headlamp, Remote Controls,etc.

I have a flashlight that came with one battery of this type, with a built in usb-c charging port. These are a little shorter than that but still fit the flashlight. And the charger works on all my other batteries so far. Good product for the price.

Works perfect for battery powered flashlight.

The batteries work as expected.

Received package as described with the double-bay charger and four 3400 mAH type 18650 batteries similar to the two shown in the first picture in the product listing. Batteries were packaged in two separate re-usable plastic storage cases with two batteries in each. One 18-inch / half-meter length charging cable was provided with a USB C connector interface on the charger body and a USB type A male connector on the other end to plug in to a mating DC power source. The charger body was in a small plastic bag. The small (about the size of a 3-inch by 4 inch documentation 'card' is a folded-in-half with the crease on the long edge) sheet of white glossy paper and small but legible (with vision corrected to standard 20/20) writing in black font on it. The outside pages are written in some variant of Chinese (simplified Chinese, perhaps) with the other side in English. While it appears to have been translated to English by someone whose first language is not English, the contents are good enough for a fluent speaker of English to comprehend what is attempting to be communicated in the contents.As far as the technical specifications that have been checked since receiving this product - Open circuit voltage of the charger (i.e., plugged in, no batteries in the charger) was 4.199 VDC on one charging bay and 4.238 VDC on the other. I am in FL, so I am not inclined to test cold charging. Charging indicator is green with no batteries in the bay, turn red when charging voltage conditions are met. The red color of the charging indicators is very dim to see even in a fairly well shaded or dark room. One pair of batteries is this is being written that were started overnight in the charger now, having been charged overnight, and are still charging. Current voltages seen across each cell are 4.071 VDC and 4.043 VDC as measured at each battery's terminals. The documentation claims that the charger is capable of providing maximium charging voltage and 1 A of current on each bay. This corresponds to the documented power input from the USB source being 5 VDC and 2 A. My source USB port is capable of providing more than 2 A. While the charging profile is likely on a tapered curve of current as voltage increases, more than 8 hours of charging a partially charged 3.4 AH battery leaves me questioning whether it ever charged at 1 A.Still, for the price, my initial impression and rating is that the charger functions effectively enough to meet my needs. Time will tell if it was a good by, so I will not make any recommendations until I have had the product long enough to determine if it meets my criteria to recommend it.

Good for charging battery

Seem to work good and hold charge

This works very good. It shows you all green when batteries fully charged up.

The batteries look great but I found to cells that were no good. I contacted Amazon and they will be sending me a new set, but the main issue is the poor fit of the batteries to the supplied charger. I went ahead and purchased another charger and they fit slightly better and I can monitor the charging status. I will update my review once I take delivery of the replacement set and can charge and test them.