Nitecore UMS4 Universal Charger 3000mA USB Adult Unisex, Black, L: 159 x W: 107 x H: 41

Since purchasing the charger as a gift to myself I have used it extensively.I waited before writing this review and have been using the charger since June.Charger is in use daily and used to charge AA, AAA, C and 18650 batteries and it is connected to a Quick charge 2 USB power adaptor. This allows the charger to charge at a higher amperage than a standard USB charger. These can be picked up pretty cheaply however the one I use is from Aukey.No manual selections here. Just insert and watch it charge. It identifies the battery type and adjusts accordingly.I have compared the charger with others of a much more expensive variety and I cannot fault this one. It just works.I have no charged over 150-200 batteries in the charger and thus far it has never failed to deliver.Something that is not written in the manual is the fact the charger can recovery batteries that would otherwise be unusable. This is great if a battery has been discharged below an identifiable level. When you insert a battery thats below a meaningful level. It will show EE on the screen. If you hold one of the buttons down it will dump a little charge into the battery and then wait a few seconds and see what the voltages are. From here the battery will be re-tested and charged. This has been very useful on a 18650 battery I had and some C batteries that a light I have discharges to 0 volts.

Great charger. Already have another nitecore charger bit needed a charger that could take the larger 21700 lithium cells and this does.Easy to use, The display tells you all you need to know regarding the charging process.All in all an excellent piece of kit.Please note that this charger unit uses a USB to micro usb cable as it accepts fast charging so you will need to buy a quick charge usb plugin adaptor plug. The fast charge does make a massive difference with charging.All in all a great charger unit.

So, yes, there are battery chargers that money can buy that are better than the UMS4.Stuff like the SKYRC MC3000 is better (well, it's really the best charger, currently), albeit expensive and not simple to use.Stuff like the Opus BT-C3100 V2.2 or the XTAR VP4 Plus Dragon are excellent, easy-to-use chargers that are somewhat comparable in price to the UMS4. They are probably better than the Nitecore UMS4, although not by that much.What the Nitecore UMS4 offers is a nice product, but specifically one that charges via USB instead of mains, which was the key selling point for me.Having a battery charger that charges via USB is really nice for me, as it's much easier to move around my desk and work area, and to connect in different places, or put it away when needed. I can just use a USB cable I have already out to connect the UMS4, rather than flaffing around trying to find the mains cable and a spare mains plug.If you travel a lot, the UMS4 would also be a great option for that too, although you'd probably be better off with something smaller - the UMS4 is big. (Around 16cm x 10.6cm x 3.8 ish cm, give or take.)This size is good though, as it can accommodate basically any battery, from a AAA/10440 to a 26700.(The UMS4 says what batteries are compatible on the back, in case you forget or lose the box or whatever, which is nice.)The design is very nice. It looks and feels like a classy, high-quality unit, and I like the design a lot.The charger also has a lot of cooling fins, which is much nicer than having fan noise.Despite this, the UMS4 is made of plastic, although doesn't feel cheap, and it is light. It's quite a bit lighter than I was expecting.There are four extremely grippy rubber feet on the bottom, so it won't slide about at all.The charging times of the UMS4 are potentially not quite as good as many other chargers with 4 cells installed, as it can only do 1A on all 4 slots, but that's the tradeoff you get from it being powered by 5V USB (18W max) instead of a 12V (or 240V) mains supply.The UMS4 can do 1A for 4 cells, 2A for 2 cells, or 3A if there is only one cell installed.Charging times are still good though, and I doubt too many people would have complaints unless they were already used to a good mains charger.The display is clear, and the buttons are intuitive - the left button changes which cell is selected, and the right button changes what info is shown about the selected cell.The display does auto-dim after a while. It doesn't go out completely, just dim. This saves a tiny bit of power, and I don't mind it, although having an option to keep it on would be nice.Similarly, the charger cycles through each cells and its information, even if you have recently changed either of them, which means you will sometimes find yourself cycling back through to what you want after it has tried to move on. A small wait time where it doesn't auto-progress would be really nice. For the most part, this isn't too problematic, but it's annoying when I am trying to monitor cells at the very beginning of their charge cycles and find myself fighting with the display.The charger can charge Ni-Mh and Li-Ion, in any combination (i.e. it has individual cell charging), and charging Li-Ions wors very well. It can do 4.2V cells, as well as 4.35V and 3.7V LiFePo4 as well. It can also un-trip protected Li-Ion. It's a really nice Li-Ion charger.Charging smaller cells also works fine electrically, however the charger really doesn't take them overly well physically.The sliding terminal that connects to the bottom negative terminal of the cell has a small protrusion on it, and is flat metal otherwise. This protrusion is quite high up on the metal, and none of my AA's and AAA's touch it when the battery is in the bottom of the slot. Instead, you have to sort of clamp the cell in the middle of the slot (vertically) so that the pip can actually connect to the bottom of the cell.This is a problem because the contact for the positive terminal of the cell is quite wide, but the edges are rounded, so cells tend to spin (as they aren't perfectly centred) then slip off of the positive contact.This can lose contact with the terminals, and thus stop charging.This means that for thinner cells it can be extremely annoying to charge them, as they are somewhat tedious to clamp into the charger and it can take a bit of wiggling to get them stable, and even then I never feel that they are secure.This affects thin cells, but not wide ones. My 16340's are perfectly fine, for example.The charger detects cell type (Ni-Mh or Li-Ion) based upon Voltage, which is fine. It assumes Li-Ion above 2.0V and Ni-Mh below 1.7V.The charger trickle charges below 0.8V.The charger defaults to charging Ni-Mh cells at 1A, which is too high. 0.5A would be better. You can change the charge rate in 0.1A increments between 0.3A and 2A.Similarly, the charger defaults to charging Li-Ion at 2A, which is too high for some types.You can adjust the charging rate, but I'd prefer it if defaulted to something low and safe with me adjusting it higher if needed, not defaulting to high with me making it safer when needed.Many Ni-Mh cells I have charged have become hot as a result. I haven't tested them with a thermometer, but hot enough that I would consider it worrying.I had a display issue with some extremely old Ni-Mh 2,500 mAh AA cells - the charger reported 0mA as the charging current for all of them, despite charging them just fine and putting over 2Ah into them.Some of the older Nitecore chargers had some issues with reported charging currents, so it might have been that they didn't quite squash that bug with the UMS4. I did only have it on one batch of very old cells though, so it may have been very bad cells and not the charger.The charger can show you the capacity it has put into the cell, the charging current, the current cell voltage, the time the cell has been charging, and the internal resistance, with a "Good" or "Poor" reading based upon that.As with basically all chargers, the IR reading is not accurate. It might be a good ballpark figure to some, but it's too inconsistent and inaccurate to be particularly useful, I think.The only real omission this charger has in terms of testing is the inability to test discharge capacity. It can tell you the charge put into a cell, but can't do discharge capacity testing, which is a real shame.Personally, I will use the UMS4 for Li-Ion primarily, which is fine for me as I don't use 10440's or 14500's, with the knowledge that the UMS4 can do Ni-Mh as well when needed, albeit perhaps with some tweaking of charging rates.Overall, the UMS4 is a good USB charger provided you don't need either IR ratings or discharge capacity testing, don't want to charge very thin cells, and either have good cells that can charge at high currents or don't mind tweaking charging currents.The UMS4 is a good charger, but those are some very hefty flaws.There are probably cheaper chargers that are still perfectly fine for most people, but the UMS4 is probably still one of the best (if not the best) USB-powered chargers if you know what you are doing, but it's very much not for everybody, and if you only want to charge AA/10440 or AAA/14500 then you should very much look elsewhere.

Charges batteries fairly quick as long as you have a fast charging plug which I already had, can fit the large 21700 batteries which is why I specifically purchased it, clear display & easy to verify if it genuine with the scratch off label on the website.....

Does everything I need and does it well, fast charge is quicker than all my previous chargers 👍

Just make sure you have a good USB plug (it doesn't have one) and then it is a great charger!

My fourth and best Nitecore charger,only upgraded as this one was smaller and supports quick charge. It does not come with a quick charge wall adaptor though and you will have to purchase one separately. Very nice and simple to use and will charge pretty much all sizes of rechargeable batteries.

Very pleased with this charger when paired with a QC3 adapter. Easily near halved the charging time of 2 21700 cells I'd been charging in an i2 for a while. As above of them suddenly died within 12 months each so fingers crossed the more expensive model is more durable. So far so good and I like the stats you can get for each slot