Review on XTAR 4-Bay Rechargeable Battery Charger for 3.6V 3.7V Li-ion IMR INR ICR 10440 18650 26650 & 1.2V Ni-MH Ni-CD Batteries - Optimized for Efficient Charging by Amanda Castillo

I increasingly need to charge/test different size Li-Ion batteries. Reasons why I chose this charger (XTAR VC4) over the Opus BT-C3400: 1. I like trying new chargers. The Opus BT-C3100/3400 is too similar to the BT-C2000 I already own and the XTAR VC4 has an interesting new display.2. I'm a curmudgeon. The VC4 is about half the price of the C3400.3. (I learned this after purchasing) The VC4 has two wider external slots that can accommodate up to D-cells. The C3400 can only accept cells up to C. The XTAR VC4 has an unusual design. For starters, it's powered by a USB port, not AC power. This makes the device lighter and independent of AC voltage. On the other hand, you should already have a reliable AC to USB adapter that can handle 2.1 amps. I have tested charging Li-ion cells from 14500 to 26650 and NiMH cells from AAA to D size external slots can be used. The attachment is very tight for a D cell, but it works [Display] The LCD panel is split in half. Each page shows the battery voltage (V) in the analog meter and the charge capacity (mAh) in the digital meter. If you insert more than two cells, only the status of the last two cells is displayed. However, you can press the SELECT button to toggle the display between cells. The central electricity meter shows the maximum charging current. Typically "1.0A" is specified when only two external slots are used and "0.5A" when more slots are used. However, not all cells are charged at the same time with the same current. With a lithium-ion cell, the current will gradually decrease as the cell is almost fully charged. This is perfectly normal. I've also seen some older NiMH batteries being charged at 0.2A instead of 0.5A. In addition, each channel has an LED display. It turns red while charging; Green when done. It's a nice touch. [Great Features] There are several features I particularly like about this charger: 1. This charger is very intelligent in detecting the chemistry of the battery. It can detect whether the cell usage is NiMH, Li-ion or Alkaline and select the charging algorithm accordingly.2. Even when the NiMH cell is discharged to almost zero volts, this charger can still detect and charge it. In contrast, most smart chargers (such as La Crosse BC1000 or Opus BT-C2000) have trouble detecting over-discharged cells.3. It can accommodate older cells with higher internal resistance. Of course, if a higher resistance element is detected, the charger will switch to a lower current. In contrast, many other smart chargers (like the Panasonic BQ-CC55) simply reject the element. [Required Features/Enhancements]1. It has no discharge mode to determine the true capacity of the cell. Instead, you can only estimate capacity based on the charge the cell picked up while charging, assuming the cell was originally fully discharged. Typically, a cell uses more charge than its actual capacity. With lithium-ion batteries, the difference is negligible, but with NiMH, the error can be 5% or more (especially if the battery is in poor condition).2. The current counter does not always give correct information. For example: When I tested charging the alkaline battery, the "NiMH" icon lit up. The ammeter says the charge current is 1A, but the actual input to the charger is only 100mA. This means that the actual cell current is probably 50mA (because the charger draws 50mA even in standby mode)3. I'm not sure yet if the VC4 will complete the charge of all NiMH cells correctly. For example, I once charged three AA NiMH batteries and the VC4 reported the same charge of 2209mAh each. I then discharged these three cells on my BT-C2000 and it showed 2041/2048/1779 mAh! I repeated this test with these three items and got almost the same results. Then I tested two different cells. Charging on the VC4 consumed 920mAh each, and discharging on the BT-C2000 showed 730/1765mAh! Further research is required. [Summary] The XTAR VC4 is inexpensive but very versatile. So far, it works great for charging lithium-ion and nickel-metal hydride batteries of various sizes. I particularly appreciate that very old or dead NiMH cells can be charged. In fact, it performs better than any of my other advanced chargers in this aspect. For this reason, despite its quirks, I give it 5 stars.