MiBOXER C4S-01 18650 Battery Charger, AA Universal Smart Battery Charger for Rechargeable Batteries Ni-MH/Ni-Cd A AA AAA Li-ion/LiFePO4/IMR 10440 14500 21700 RCR123 26650

Seems like a charger with nice features but I have encountered one oddity and one undocumented situation.The undocumented item I don't consider a problem, just wanted to make note of it. Pressing the Slot button will only change to the next slot if the back light is already on. If the light is off, pressing Slot only turns on the back light. The button must be pressed again to change to the next slot.Now the oddity...When charging four NiMH batteries, the battery loaded in the last slot will charge VERY SLOWLY. It will eventually charge to full capacity but it will take significantly longer than the other three batteries. I have tested this loading four batteries varying the final slot - that final slot will be slow. For example, I have loaded C1, C2, C3, C4 - this causes C4 to be the slow slot. I have also loaded C4, C3, C2, C1 - this causes C1 to be the slow slot. I don't know if this will also happen with other battery types. I don't know what happens if I load less than four batteries.I have tried increasing the charging current on the final slot but it does not make a difference. It will still charge the slowest. When the other batteries are done, if I move the battery from the slowest slot to another slot, it will charge faster.I have used several other charges through the years and I've never had one exhibit this behavior before.

Pro:1) ability to read internal resistance on all slots2) ability to do a full discharge/recharge cycle in slot 43) solid design4) regular AC power cable instead of external transformer5) can do LiFePO batteries at 3.2 v6) backlight goes off or you can turn it off manually.Cons:1) no car adapter included. You have to buy it separately: Miboxer smart car charger 5v/12v two voltage outputs 2.0A USB power cord suitable with Car/SUV/Trucks/charging fast for Iphone 8,Samsung etc2) can ONLY do a full capacity test in slot 43) Difficult to grab and remove batteries. Why not undercut slots 1 and 4 from the sides and have divits between slots 1-2 and 3-4 so you can slip your finger in?4) were they paying for extra buttons? This thing has two buttons ONLY and most of the controls are through short or long presses of the second button only. Would it hurt to have more buttons?5) the instructions were utterly useless. I had to figure it out by trial and error. The programming language for this is Morse code. Seriously, it's a series of long and short pulses. But, instead of giving you the ACTUAL codes in the instruction manual, we get Chinenglish gibberish. Just give me a chart: to do this, press this series of dots and dashes.6) did I mention that it didn't include a car charger?Update: June 2018- Okay, this thing will charge CR2 batteries, but you need a spacer. I used spent .32 ACP cartridges, but I suppose you can stack a few coins at the top and it would work. I have to use LiFePo4 batteries for three of my devices that don't like the 3.7v batteries.

It charged my batteries much faster than any charger I have had before. There is an option to select the Amp's rate to charge your batteries faster, and I dialed the Amps to 3 A for my 18650 batteries. Once, I decided to dial the Amps to 500 mA and a battery was over-charged to 4.33 v !!! This happened more than once with different batteries, and not just a single faulty battery. Most of the times things are good, but there were those instances when the charger charges a battery over the 4.20 volts capacity. Oddly enough, when I dialed the Amps to 3 A, batteries were never over-charged! Still, this thing got me scared to the point that the charger is now setting and collecting dust.I am giving this a rating of one star because it is hazardous. If it did not over-charge, this will get 5 stars. I know this might appear an extreme way of rating, but the charger is flawless and checks all the boxes so it is a real 5-star, but if a product can harm your property then it becomes a harmful-one-stared product.

A good measure of a product is their customer service and these guys are great. I had a few questions that were promptly addressed.I like the display a lot and the build quality is very good. Overall the user interface is very easy to understand. Something that threw me at first but seems obvious now is that the mAh are listed in the instructions as Battery Capacity but it is really more like Charge Accepted or something like that. A very minor nit is that I wish the AAA battery holder had a storage place somewhere on the charger so I didn’t have to worry about losing it. The grip on the battery is very secure but I do wish the end of the tray was open so I could pull the slide back more easily and not use the battery to move it.These are all very minor issues. Charging Li-ion batteries is serious business and I really love the feedback and information this charger supplies. And I appreciate the safeguards claimed in the design. Good charger.

I really wanted to like this one. The display has a lot of useful information, and I like that each cell can be controlled. I also like that the power to this unit is just an AC cord, and not an external brick or USB connector. However, the fact that there's no discharge/test cycle, which it sounded like there was, was a bit of a deal breaker for me. That and one of the sets of harvested 18650's that I was testing got so hot that I could feel the heat radiating from them, and I couldn't even touch them. I unplugged the charger, put a fan next to them, attempting to cool them, and after about 5-10 minutes they had cooled to the point where I could touch them. I didn't even realize there was a problem until I happened to bring my hand near the charger, and I was confused by the heat. The retaining clip for slot #2 was actually damaged due to the heat. Had I not realized there was a problem, it's entirely possible that these batteries would eventually have caught fire.

Works well and fast with mixed battery types charging at the same time