BT - C3100 V2.2 Universal Battery Charger Speedy LCD Display Smart Battery Charger for Rechargeable Batteries Ni-MH Ni-Cd AA AAA,3.7V Li-ion 18650 26650 17670 14500 18490 (4-Slot)

When I saw the price of this battery charger and tester, I almost passed on buying it. I went ahead and bought it to give it a try based on the reviews. I am glad I went ahead and got it.I really like the fact that you can charge as many batteries as you want to charge, from a single battery to four at once, with this charger and tester. I also like the way it plugs into the wall outlet with the transformer plugging into the outlet and having a cord so it can moved around on the counter while the batteries are charging. I had several old rechargeable batteries and I knew some of them were not good anymore and with this charger I was able to charge and test all of my AA and AAA NMH and NiCad batteries. I found four batteries that were no good and would not take a charge and was able to get four batteries that would not charge with a standard charger to take and hold a charge with the discharge refresh cycle built in to this charger and tester. I want to note here that I had tried to charge the batteries that came back to life with a standard battery charger they came with for two days before placing them in the new charger, but the new tester showed they had not taken a charge and showed zero voltage when first put in the new charger and tester. The ability to find the bad batteries is reason enough alone to warrant the purchase of this charger. The fact that it will actually bring some dead batteries back to life, instead of just getting rid of them to a recycling station is a great feature and makes it an even better value. After changing some of the original settings I did unplug the unit to reset it to the factory charging settings. The fact I had to unplug it and start over again was not a big deal to me but was a bit of an inconvenience. I also like the fact that this unit has a fan that runs when needed to help keep the batteries and the charging unit cool. I didn't notice any overeating problems when charging either the good batteries I had or the batteries that were no longer any good.I would definitely buy this charger and tester again based on the experience I have had so far. I wish I had bought it sooner so I could have gotten rid of the batteries that weren't any good.

Out of the Box:The unit came with the base station, and power supply and Manual.Pros:I found these to be very well design elements of this unit both before, during and after using it:Modes: There are 5 different modes that can be selected for the unit to perform. Charging, Discharging, Refresh, Test, and Quick Test. Having this many options for your batteries is quite nice!Overheating protection: It has a temperature control monitor and a cooling fan built into the system and it does a very nice job. But that doesn't mean you shouldn't monitor the batteries. When you get a "heater" on you hands, the unit will keep dumping more and more power into that bad battery and struggle to keep the unit cool. I have a laser temperature unit to keep track of the batteries.Display: I found this very useful. you can cycle through all the settings the unit is currently set for without disrupting the process, including the current status of the process that it is doing.Current: This is my favorite part of the unit. You can charge or discharge 4 cells at the same time at 1000mAh or 1 amp for Lithium Ion cells. you are also given charging options of 200, 300, 500, 700, 1000, 1500 and 2000mAh. However for the upper charging mAh options you have to use certain slots and only 2 can be done at the same time.Voltage meter: Now I only use the voltage from my multimeter as the actual voltage of a cell. But this unit isn't dumb. If it reads that the voltage of a cell is low, it will not simple start dumping the selected mAh current you selected into the cell. It automatically drops the current down to a very small "trickle" charge until the voltage comes up enough to start putting in the selected current. I like this feature!Backlit Display: You have the option of having the backlit display on all the time or having it turn itself off after a preprogrammed amount of time.Multiple Cell options: Way too many to list here, but trust me this baby can handle all kinds of batteries.Cons:Resetting: I've not figured out what the conditions are that cause this unit to reset during the charging process. It's not over heating, or power drops or the power supply, but for some reason the unit will auto reset to the default charge settings which are 500mAh. the only thing I have figured out that overrides this is to select all the bays and cycles through the modes back to charge and setting the current back to 1000mAh. Very frustrating indeed considering how much I like this unit.Fans: While I did list this as a big Pro, it is also a Con in the fact that there is a balancing problem with how these units are manufactured. The fans will try to spin up and make a hell of a noise because they are out of balance or something. This happens multiple times until finally they start to spin up without issue. I've learned to live with it, but it is something to consider if you are planning on buying this unit.Wish List:More powerful power supply unit. The PSU that comes with the device does a good job, but it is only rated at 12DC and input of 100-240V at 50/60Hz and the output is 12v DC at 3.0A, which seems odd that it can charge at 4A. So IMO a more powerful PSU is needed.Personal experience:I'm building a DIY powerwall for my house, and I have 1000's of 18650 cells to process. I have 5 of these units working around the clock and other than the Con I listed regarding resetting (which only happens on the oldest unit) these babies do a great job!Bottom Line:Overall this product works as advertised, and performs perfectly on both large and small jobs.Recommendation:Damn Good Buy!