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 LumenTac Battery Organizer

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.

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

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 have a couple of Nitecore D4 chargers and they’ve been great. Looked at getting the Nitecore SC4 charger but saw reviews that while charging, it does make a hissing sound. I didn’t want to deal with a charger that makes any noise and wanted to be able to charge 21700 batteries. The UMS4 met my needs. It comes with a micro USB cable but you have to use your own power supply which can be a power brick you use to charge your phone or tablet, etc. It does support fast charging but you have to have QC power brick to do so. You can also increase or decrease the rate of the charging for each bay. Example would be to charge small batteries like AA or AAA batteries at a lower setting so the batteries lifespan is not shortened.

Works on many rechargable batteries. But I primarily use them for 18650 batteries. And, they not only work great, they tell you everything you need to know about the batteries you are charging. Easy to tell if something is wrong, or going wrong with a battery.

I was stunned at how many different types of batteries this unit can charge. And the display gives you the charge status.