XTAR's VC series of USB powered, multi-chemistry chargers have been popular since they were first introduced in 2015. Every few years there have been newer iterations, and the latest version of the VC4 is the highly specified VC4SL (also known as the VC4 PLUS).
The XTAR VC4SL was sent to me from XTAR for an honest review.
The XTAR VC4SL is a USB powered, 4 bay multi-chemistry charger. The size is 156mm x115mm x 35mm, and constructed from flame retardant and fire resistant ABS materials. The VC4SL has the display and buttons located above the charging slots. The power supply is USB QC3.0 (5V-3A/9V-2A), so to maximise performance, you will require a USB QC3.0 power supply/wall adapter. This wasn't included with my review sample, but there are options for US, EU, and UK adaptors on XTAR's AliExpress Store. I don't know if adapters will be included for retail sales - so check before you buy. A USB-A (power source) to USB-C (charger) cable is included, as is a draw string bag, and instructions (with very small text).
The VC4SL has slots long enough for protected 21700s at 79.5mm. It will charge the following batteries according to XTAR:
Li-ion 3.6V/3.7V - 10440, 14500, 14650, 16340, 17335, 17500, 17670, 18350, 18490, 18500, 18650, 18700, 20700, 21700, 22650, 25500, 26650, 32650.
NiMH - AAAA, AAA, AA, A, SC, C, D.
The VC4SL will thus charge the vast majority of currently available cylindrical batteries, including Li-ion sizes in-between the listed sizes. The VC4SL will not charge 26800 batteries (well probably not - I don't have one to test), LifePO4 4.2V batteries, though both of these have very limited uses in torches/flashlights. The VC4SL may also not be able to charge some of the newer generation of proprietary li-ion batteries (with positive and negative terminals at one end) that some flashlight manufacturers are now producing to maximise their own profit margins.
User Interface and Charging Rates
Using a QC3.0 USB power supply I was able to charge 3 or 4 batteries at 1A, 2 batteries at 2A, or 1 battery at 3A.
Using a standard 5V 2.4A USB power supply, I was able to charge 3 or 4 batteries at 0.5A, 2 batteries at 1A, and 1 battery at 2A.
The charger is controlled by 2 buttons - Curr and Mode.
By default, the charger is in charge mode, and charges all batteries at the current selected by pressing the Curr button - which cycles through 250mA, 500mA, 1000mA, 2000mA, and 3000mA. This applied to all 4 slots. If you select a higher charging current than what the charger is capable of (e.g. 3000mAh for 4 batteries), then it will select the maximum charge possible. If the charge is reduced in one battery (e.g. close to terminating charge), and a higher charging current was selected, then the charge will be increased in the remaining batteries. If you do not manually select a current, the charger appears to automatically select the charger current based on IR, as it charged an AAA NiMH at 0.5A whilst simultaneously charging a 3 Li-ion at 1A. I would prefer default charging current to be a lower setting than 3000mA, as many batteries cannot handle this current.
Pressing the Mode button will cycle through actual charging current, internal resistance (IR), and charged capacity on the display. When the battery is full, the measurements will alternate with "FULL". A dial like display is available for all 4 slots, which shows charging current, and voltage in 6 increments. Unfortunately the actual/accurate battery voltage is not displayed, and neither is percentage % full (the former is more popular with enthusiasts, the latter is more popular with consumers). There are also coloured indicator lights for each slot, red for charging, green for FULL/slot empty/grading/at storage voltage. The light is quite dim.
A long press of the Mode button will take the charger into "Grad" (grade) mode and then "Store" mode.
"Grad" analysing functionality is rather skipped over the manual. It charges, discharges, and charges again. Only the discharge capacity is recorded. I would prefer both to be recorded as per the XTAR VP4 Plus Dragon. IR, and actual charge/discharge rate is not displayed in "Grad" mode. "Store" mode discharges to storage voltage of 3.7V, with the voltage not stated in the manual.
The XTAR VC4SL had no problems charging over-discharged NiMH batteries, which is one of the few negative points on the Vapcell S4 Plus (I have to use another charger to jump start over discharged NiMH batteries before it recognises them). However, some reviewers have found that this charger terminates NiMH charging too soon. I have also observed the charger mistaking a NiMH battery for Li-ion. Thus you do need to keep an eye on the charger when you start charging.
I'll note that I had connectivity issues with one of my Samsung 30Q batteries, and maybe the positive connection point needs to have more of a protruding bump.
Things I liked:
Good value for money.
Fits the vast majority of cylindrical NiMH and Li-ion batteries, including protected 21700.
Analysing functionality (though with limitations and limited information in the manual).
Recognises over discharged NiMH batteries.
Good choice of charging rates.
Things I didn't like:
Voltage display is only steps - I would prefer voltage to be displayed accurate to 2 decimal places (e.g. 4.19V).
No percentage full indication.
I had connectivity issues with a flat top 30Q battery.
Can terminate charge too early for NiMH.
Can mistake NiMH for Li-ion.
Defaults to highest current.
As with all XTAR chargers, the VC4SL is high quality, well constructed, and good value for money. It is a good update to the VC series, with good battery compatibility and basic analysing functions. It is thus one of the best USB powered, and consumer chargers available. It could be improved with more accurate voltage display, % full display, and both charge/discharge capacity analysing, and improvements to firmware for NiMH charging.
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