It became my favorite charger!
I will explain in detail, hoping my experience helps someone.
My profile:
I mainly use 18650 for electronic cigarettes but also 21700 and AA and AAA for various applications.
Currently, I own 3 other chargers:
NiteCore D4, NiteCore UM4, LiitoKala LII-202
Charging theory:
The theory says that for a battery to last longer, it needs:
1. Slow charging
2. Not to be fully discharged
Many say this is not entirely true yet, but I consider it safer and I see it in practice with my e-cigarette batteries, which since 2021 have hardly lost any capacity.
My evaluation:
It is now my favorite charger because:
- It has slow charging by default, which I consider essential! If you want, you can choose a stronger charge, but you have to press buttons! On the 2 Nitecore chargers I have, fast charging starts and you can make it slow with buttons. So, the logic of this XTAR saves me settings and button presses.
- It has type C input! The most modern option available right now. In contrast, the NiteCore D4 has a 220V plug, and the NiteCore UM4 and LiitoKala LII-202 use Micro USB (yesterday's news)
- It has a capacity measurement function, which I don't know how accurate it is, but it gives almost the same numbers every time you measure the same battery
- It has a "battery storage" function, which means it charges not to the MAX voltage of the battery, something that also helps with battery longevity

The only "unfortunately" is this screen... to keep it from staying on with such a bright light, you have to press and hold a button every time you finish charging... it could have, by default, a dimming feature like the NiteCore D4.

This is the third Xtar charger I am buying; the previous two (MC2 the first and VC2S the second) work flawlessly after several years, about 6 and 3 respectively. In terms of quality, it is fine for its price category, but I really dislike the feel and material of the two buttons; they give a cheap construction feel, and you think the charger is....hollow. I suppose they could have used a foam material for a better feel, but it's not a significant issue. Also, I would like the red/green charging indicators to be MUCH more pronounced, as they are barely distinguishable unless you look at the charger from directly above, especially the red one, which you can only guess by seeing how many green lights are on! On the two side edges left and right of the screen, there are large air vents, so it neither heats up nor risks burning; just be careful with cleaning: do not push the dust inside. In my charger, the Type C port is relatively sensitive, and the charger must be stationary. Regarding charging, I have charged 18650, 20700, 21700, AA, and AAA without any issues; in fact, the AA and AAA did not need to be positioned at an angle. With the left button, you can adjust the Amperes (it has 5 options: 3A, 2A, 1A, 0.5A, and 0.25A), and with the right, you select the charger’s mode (it has 3 options: charging, calibration, and storage) by pressing and holding the button. Also, by pressing and holding the left button, you can turn off the display; I do this almost always because it makes the green/red lights slightly more distinguishable. At 3A, it charges only one battery; personally, I avoid charging above 1A for Lithium Ion batteries and 0.25A for Nickel Metal batteries for longer battery life. The manual states that it also charges Nickel Cadmium, but I haven't tried it. In charging, by pressing the right button, you have 3 sub-options: In the first, you see the Amps the battery has received; in the second, the Amps at which the battery is charging; and in the third, the IR which shows the internal resistance of the battery; the smaller the number, the better the condition of the battery. In calibration, it shows the battery's capacity. To calculate it, it does 1.5 cycles, meaning a full charge, discharge, and then charge again. I always use this function on every new battery to ensure it's not a fake and for smoother operation. In storage, it completely discharges the battery and recharges it to half capacity so you can store them. * In the calibration and storage modes, you cannot change the Amps; the charger decides that on its own.

As for the negatives, I only find the Type C port being relatively loose, but that might only apply to mine; I would like the red/green indicators to be much brighter and a very cheap on/off switch. * Xstar claims it can revive dead batteries; I haven't tried it and have no opinion. ** If a slot stops charging, remove the cable slightly from the charger and then reconnect it. This has not happened to me with this one, but with the VC2S, it solved the problem. *** If you put even one AAA for calibration, forget about the charger until it completes; you cannot charge anything. **** If you are interested in calibration, charge the batteries first; you will save A LOT of time.

EDIT: The charger literally does whatever it wants! Ignores the setting for charging at 1A and decides on its own, it charged the same battery at 2A and then at 0.5A, a little while ago I put a battery for charging and when I tried to see at what A it charges, it started showing that it is discharging (??!!) while it shows it as full. I don't know if it's a coincidence that it has now rendered two old batteries useless, I assume not. In any case, they had a high internal resistance due to age and frequent use and it didn't bother me much but... they were working.