Nitecore UMS4 Intelligent USB Four Slot Quick Battery Charger for Li-Ion/Ni-MH/Ni-Cd/IMR 16340 14500 18650 21700 20700 AA AAA and More Batteries, with Organizer

This is a really handy charger. Someone had given me a few rechargeable flashlights that did not come with chargers. I order this thing and it has worked really well. Tells you exactly what it is doing and all of the lights work like a charm now. It also looks like I will be able to charge other batteries that I might have the in the future.

I have 4 of these Nitecore USM4 chargers and use them with 18650, 21700, and rechargeable AA and AAA batteries. They are very easy to use and have lots of great features. I especially like that they won’t overcharge a battery and can be used to reactivate an over discharged lithium ion battery.The only drawback is that the power cable is USB to Micro USB. That seems very old school and behind the times.Important!! The chargers are definitely capable of quick charging batteries but you need a quality QC charging block that supports the QC protocols and not just an 18-20 watt charging block.

great charger, pretty fast too. my only gripe is that its very tight and makes removing the batteries a lil inconvenient. but i think that will become better once the springs loosen with time.

This review is for Nitecore UMS4I bought this to revive a battery for my TT20 flashlight that recently stopped working, and when I tested the voltage with a multimeter, it was like .03, so I figured that was the issue. This recharger was able to revive it, but it was a bit tricky. With only that battery in the recharger, it would not stay on longer than 30 seconds or whatever the auto shutoff timer is. When I put it on the charger, it was recognizing there was a battery there, but would not stay on. I was able to get around this issue, by placing another battery in a different slot, and have it charge while the problem battery was getting recharged. It took awhile, and I had to replace the extra battery that I was using to keep the unit on (swapped to another battery that needed recharging). Eventually, the battery I was reviving had enough charge for the unit to stay on, and it fully charged, and works now.Since a brand new battery of that kind (thrunite 21700 proprietary battery) was almost as much as a charger, I figured I would just get the charger and see if it works, and it did. The charger itself seems decent enough, the display was bright, and it presented all the information that I needed. I really dislike how it uses usb micro, but with all the adapters and bricks I have laying around, it's not a big deal I guess.

I've had this charger for a week now and have used it to charge about 20 NiMH batteries and 8 Lithium-Ion batteries. My impressions so far have been overwhelmingly positive.First impressions: Taking this charger out of the box, I immediately noticed that it weighed at least 3 times what my cheapo Lithium-Ion capable chargers weighed.In use: The display on the charger is crazy useful. Type of battery detected. Level of charge detection mechanism (e.g. dv/dt). Battery internal resistance. Battery voltage. How much charge has been added to the battery. Expected time to completion. Batteries charge pretty quickly. My model has the USB cable, so any reasonable USB adapter or USB outlet will work. None of my batteries got beyond mildly warm, and the charger itself did not get hot. Each slot is independent, so battery types can be mixed and matched. The display cycles through multiple screens for each slot, but two buttons allow the user to rotate to a particular slot and screen quickly.The bad: O.K. this is an expensive charger compared to all those cheap/free chargers you can find bundled with batteries or flashlights. Truth be told, this is the only one that gives me any confidence it won't overcharge, explode, or melt down. Also, this is a pretty big unit, partially because it can accommodate everything from smaller than AAA to larger than 18650. There is also a generous space between slots, which is nice for cooling (and those with bigger hands).The summary: I immediately threw my cheapo Lithium-Ion chargers away, and doubt I will ever use my reasonable Panasonic NiMH/NiCad charger again.

Best charger of this style out there.I use it on a 5 port 60w Anker power brick. If I use it with a good microusb cable and the quickcharge 3 port I can get 2a on every slot and it's not supposed to do that. I instead always use a magnetic disconnect microusb to USB cable so I don't wear out the port or cable and it's been great. Still get 2A on one or 1A on all 4.If you use it on a weaker power supply it will charge slower. It only works very fast with my big Anker, my small 20w one can't kick it up to full speed. I'm assuming any old charger will run at slower speeds. I'd recommend getting a nice anker 5 port (I have the one with the quickcharge 3 slot up top)This charges everything I have. 21700's fit, nimh charges good, if not too fast(have to manually turn it down for AA and AAA) nimh D batteries fit with no modifications, but only 2 at a time.Can't recommend it enough, my only gripe is the screen never dims. But that's not worth deducting anything. Debating getting a second.2022 update: the display on mine died. The first time(December 2021) I was able to bring it back by heating it up with a hair dryer. The second time(June 2022) it wasn't coming back. Still worked though. I ended up going with the faster Nitecore charger, the display on it looks better, but I still miss this one. Still 5 stars

Perfectly works as advertised works like a charm. Doesn't get very hot, just warm.If you look for the ohm symbol on the right hand part of the screen that's the internal resistance that the battery has to charging, and that will give you an idea of the overall internal health of the cell and where it is in its life cycle for whatever type of cell you're using. You can easily Google or ChatGPt you're given battery cell type to find out what level of internal resistance, a new, vs a used, vs a dying cell should have.