XTAR VC8S Charger

Specifications

Brand/model XTAR VC8S
Slots 8
Input PD3.0 (15V⎓3A). QC3.0 (9V⎓2A)/(5V⎓2A)
Constant Current 4.2V⎓3Ax2 / 2Ax4 / 1Ax8 / 0.5Ax8 / 0.25Ax8. 1.45V⎓0.5Ax8
Cut-Off Voltage 4.2±0.05V / 1.45±0.01V
Cut-Off Current ⩽150mA
Operating Temperature 0-40℃
Review date January 2024

Introduction

The XTAR VC8S is an eight slot Li-ion and Ni-MH charger with USB-C PD3 and QC3 input.

One of the main improvements over the XTAR VC8 is that the VC8S can use all eight slots for storage and capacity test modes. And I noticed that 26800 cells fit too!

Previously you had to put a cell in slot 1 or 8 to charge a Li-ion cell at 3A but the VC8S allows you to use any slot to charge two cells at 3A each (i.e. one cell in slots 1 to 4 and another cell in slots 5 to 8 for 2x 3A charging).

Here is a quick look at the XTAR VC8S:

I gave my XTAR VC8 away. I wasn’t happy with the termination voltage varying between 4.13V and 4.20V. So I am keen to see how this VC8S performs!

XTAR kindly sent this charger for review. I have not been paid for this review nor have I held back my opinions of this charger.

Packaging

The XTAR VC8S comes in a white box with an image of the charger on the front.

The sample that I received was so new that the final retail box had not yet been produced and I was provided with a digital copy of the user manual instead of a printed copy.

XTAR VC8S front

The following is included in the XTAR VC8S SET:

  • XTAR VC8S
  • USB-C to USB-C cable
  • User manual
  • XTAR USB-C PD 45W Power Adapter

The XTAR VC8S KIT is available without the bundled power adapter:

  • XTAR VC8S
  • USB-A to USB-C cable
  • USB-C to USB-C cable
  • User manual

XTAR VC8S closeup-charging-1 XTAR VC8S closeup-charging-2

XTAR VC8S accessories

Here are some screenshots of an early version of the user manual:

XTAR VC8S user manual XTAR VC8S user manual

User interface

The XTAR VC8S has four buttons. “Mode” and “Curr.” buttons appear twice. They are used to control two groups of four slots.

XTAR VC8S closeup-buttons

The VC8S is a bit like two VC4SL chargers put together in a slightly more compact form.

There are three modes:

  1. Charge Mode
  2. Grade Mode (Capacity Test Mode)
  3. Store Mode
Mode Action Result
Charge Click Mode Cycle the display to show (Capacity, Internal Resistance, Current)
Charge Long press Mode Cycle the selected mode (Charge, Grade, Store)
Charge Click Curr. Cycle the charging current (3A, 2A, 1A, 0.5A, 0.25A) for Li-ion
Charge Long press Curr. Turn the display off
Grade Click Mode Cycle the display to show (Status, Current, Internal Resistance)
Grade Long press Mode Cycle the selected mode (Charge, Grade, Store)
Grade Click Curr. Cycle the charging current (3A, 2A, 1A, 0.5A, 0.25A) for Li-ion
Grade Long press Curr. Turn the display off
Store Click Mode Cycle the display to show (Status, Current, Internal Resistance)
Store Long press Mode Cycle the selected mode (Charge, Grade, Store)
Store Click Curr. Cycle the charging current (3A, 2A, 1A, 0.5A, 0.25A) for Li-ion
Store Long press Curr. Turn the display off

The “Curr.” button isn’t meant to do anything when clicked while in Grade or Store modes but I found that clicking that button will result in the charging current being adjusted (if applicable).

The display will show the Capacity, Internal Resistance or the Current while in Charge mode:

XTAR VC8S closeup-capacity XTAR VC8S closeup-internal-resistance

XTAR VC8S closeup-current

The display will show the status (ChG, dChG, donE) for the Grade and Store modes by default. This lets you know what the charger is doing (i.e. charging, discharging, done). Clicking the “Mode” button will change the display to show the: Status, Current and Internal Resistance.

The display can be turned off by long pressing the “Curr.” button and turned on by clicking the “Curr.” button.

XTAR VC8S closeup-display

Each group of slots are operated separately. So if I want to use Store mode for eight cells then I will need to long press each “Mode” button until both groups are in the Store mode.

Individual slots can support different battery chemistries. You can have Li-ion and Ni-MH cells in different slots and the charger will automatically select 500mA for the Ni-MH cells and default to an appropriate current for the Li-ion cells based on the internal resistance that has been detected.

There is a battery identification stage where the charger may spend ten minutes trying to identify whether a 1.2V Ni-MH cell has been inserted or whether a Li-ion cell with a very low voltage has been inserted.

I highly recommend reading through the user manual.

Charger in use

It is pretty easy to use the XTAR VC8S with larger Li-ion cells like 18650 and 21700 cells. Button top and flat top cells fit comfortably.

XTAR VC8S front XTAR VC8S front-cells

I find it a bit difficult to use the charger with small cells.

10440, 14500 and 16340 cells need a bit of extra care when being inserted. The negative end of the cells need to be balanced against the negative notch in a slot. If the cell is pushed down toward the bottom of a slot then any wrap around the edge of the negative end of a cell may prevent the cell from making a connection.

1.2V Ni-MH eneloop AAA and AA batteries don’t have a wrap that overlaps the negative end so I can simply put an AAA or an AA battery in without thinking. It just works.

XTAR VC8S closeup-slots-1 XTAR VC8S side-cells

The sliders in each slot move smoothly. They seem to have enough force to clamp down on a battery and keep it in place.

The positive and negative ends of each slot have small notches. These work well with flat ends of cells.

The positive notches would be better if they were a bit longer so that the charger could work with proprietary cells with recessed ends.

XTAR VC8S closeup-slots-2 XTAR VC8S closeup-slots-3

The feet on the base of the charger could be a bit longer. I found that the charger would spin around on the middle foot but after wearing it down from normal wear and tear, the charger now stays put on a table due to the feet.

XTAR VC8S back XTAR VC8S closeup-feet

Store mode (Li-ion)

XTAR VC8S store-li-ion-1

Store mode discharged eight Li-ion cells from 4.20V to 3.60V at a rate of 300mA. It takes a long time to discharge to 3.60V.

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Voltage 3.61 3.61 3.63 3.62 3.60 3.60 3.59 3.59
Battery 50S 50S GA GA VTC6 VTC6 P42A P42A

XTAR VC8S store-li-ion-2

Store mode charged eight Li-ion cells from approximately 3V to 3.60V.

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Start voltage 2.837 2.833 3.007 3.016 2.955 2.972 2.965 2.978
End voltage 3.608 3.608 3.602 3.603 3.587 3.586 3.593 3.593
Battery 50S 50S GA GA VTC6 VTC6 P42A P42A

Store mode (Ni-MH)

XTAR VC8S store-nimh-1 XTAR VC8S store-nimh-2

XTAR VC8S store-nimh-3

Store mode initially charged the eight eneloop pro AA Ni-MH 2450mAh cells from 1.39V at a rate of 120mA for 10 minutes and displayed “ChG” and flashed “Ni-MH”. Once the detection stage completed, the VC8S discharged the cells to about 1.32V at a rate of 300mA.

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Start voltage 1.395 1.396 1.395 1.397 1.395 1.393 1.392 1.390
End voltage 1.321 1.321 1.318 1.348 1.312 1.313 1.317 1.321
Battery AA AA AA AA AA AA AA AA

XTAR VC8S store-nimh-4 XTAR VC8S store-nimh-5

Store mode charged the eight eneloop pro AA Ni-MH 2450mAh cells from 1.04V-1.11V to about 1.35V.

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Start voltage 1.043 1.047 1.044 1.077 1.107 1.105 1.111 1.084
End voltage 1.361 1.361 1.361 1.361 1.354 1.352 1.354 1.352
Battery AA AA AA AA AA AA AA AA

Charging (Li-ion and Ni-MH)

XTAR VC8S charging-1

I inserted four Li-ion and four Ni-MH cells into the charger and then I connected it to a USB-C PD power supply to let it automatically start charging.

The following cells were inserted:

CH1: Sofirn 21700 Li-ion 5000mAh
CH2: NEXTORCH 21700 Li-ion 5000mAh USB-C
CH3: eneloop AA Ni-MH 1900mAh
CH4: LADDA AA Ni-MH 2450mAh
CH5: Wuben 18350 Li-ion 1100mAh
CH6: eneloop pro AAA 900mAh
CH7: eneloop pro AAA 900mAh
CH8: Sofirn 21700 Li-ion 5000mAh

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Voltage 4.182 4.206 1.406 1.420 4.139 1.423 1.421 4.172
Battery 21700 21700 AA AA 18350 AAA AAA 21700

CH2-CH7 finished first. I left the cells in while CH1 and CH8 continued charging.

I put the 18350 cell back in CH5 and it charged to 4.165V. The termination voltage looks ok. The cell may have discharged slowly while waiting for the other cells to finish charging.

Charging (Ni-MH)

XTAR VC8S charging-nimh-1

Eight eneloop pro AA Ni-MH 2450mAh charged at a rate of 500mA from 1.39V to 1.45V.

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Voltage 1.446 1.445 1.447 1.456 1.453 1.458 1.451 1.450
Battery AA AA AA AA AA AA AA AA

Charging (Li-ion)

XTAR VC8S charging-li-ion-1

The following cells were inserted:

CH1: Vapcell 10440 Li-ion 320mAh (flat top)
CH2: Vapcell 10440 Li-ion 320mAh (button top)
CH3: Vapcell 10440 Li-ion 320mAh (button top)
CH4: Vapcell 10440 Li-ion 320mAh (button top)
CH5: Shockli 14500 Li-ion 1050mAh (flat top)
CH6: Acebeam 14500 Li-ion 920mAh USB-C
CH7: Manker 14500 Li-ion 920mAh USB-C
CH8: Vapcell H10 14500 Li-ion 1100mAh (button top)

I had to balance the flat ends of the cells against the notches on the terminals. It was a bit tricky.

The charging rate was automatically selected as 250mA for most of the cells except for CH6 where the 14500 cell was charged at 500mA. The current gradually decreased below 150mA.

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Voltage 4.135 4.176 4.151 4.178 4.176 4.155 4.160 4.156
Battery 10440 10440 10440 10440 14500 14500 14500 14500

2A charging (Li-ion)

15V 2.6A input from a PinePower USB-D PD port.

XTAR VC8S charging-2a-1 XTAR VC8S charging-2a-2

Four 21700 cells charged at a rate of 2A each.

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Voltage 4.206 4.205 4.188 4.189
Battery 50S 50S P42A P42A

XTAR VC8S charging-2a-3

Four 18650 cells charged at a rate of 2A each.

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Voltage 4.183 4.185 4.178 4.178
Battery GA GA VTC6 VTC6

3A charging (Li-ion)

XTAR VC8S charging-3a-1 XTAR VC8S charging-3a-2

Two 21700 cells charged at a rate of 3A each.

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Voltage 4.196 4.180
Battery 40T 40T

Grade mode (Li-ion)

Grade mode will charge the Li-ion cells until they are full (4.20V), discharge the cells down to 2.50V at a rate of 300mA and display the capacity (e.g. 4000mAh), and charge the cells until they are full again (4.20V).

Room temperature: 25 C
Maximum surface temperature: 51.2 C

XTAR VC8S grade-li-ion-1

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Capacity (mAh) 5213 5271 3508 3529 3064 3034 4010 4014
Voltage 4.207 4.211 4.182 4.184 4.178 4.176 4.183 4.181
Battery 50S 50S GA GA VTC6 VTC6 P42A P42A

Grade mode (Ni-MH)

Grade mode will charge the Ni-MH cells until they are full (1.45V), discharge the cells down to 1V at a rate of 300mA and display the capacity (e.g. 2450mAh), and charge the cells until they are full again (1.45V).

Room temperature: 25 C
Maximum surface temperature: 32.6 C

XTAR VC8S grade-li-ion-1

CH1 CH2 CH3 CH4 CH5 CH6 CH7 CH8
Capacity (mAh) 2543 2583 2539 2654 2651 2626 2659 2583
Voltage 1.395 1.396 1.395 1.397 1.395 1.393 1.392 1.390
Battery AA AA AA AA AA AA AA AA

The eneloop pro AA Ni-MH 2450mAh cells in CH1-CH4 are from 2019 and the cells in CH5-CH8 are from 2022.

Dimensions and weight

Dimensions

I took the following measurements using a digtal caliper and a ruler.

Measurement Unit (mm)
Charger height 39.2
Charger width 151.7
Charger length 210
Shortest cell length 29.3
Longest cell length 81.1

XTAR VC8S supports cell lengths between 30mm and 80mm.

Weight

I took the following measurements using a digital scale.

Weight Unit (g)
XTAR VC8S 460

Standby drain

The XTAR VC8S discharged a Li-ion cell at about 1 mA and it discharged a Ni-MH cell at about 78 uA while the power was disconnected.

Batteries

The following cells are supported:

Cell Type Sizes
3.6V/3.7V Li-ion, IMR, INR, ICR 10440, 14500, 14650, 16340, 17500, 17670, 18350, 18490, 18500, 18650, 18700, 20700, 21700, 22650, 25500, 26650
1.2V Ni-MH AAA, AA, SC, C

Protected or unprotected Li-ion cells from the above list with a length from 30mm to 80mm are supported.

LiFePo4 can be charged to 3.6V by using Store mode.

Proprietary Olight 18350 cells did not fit. The notch on the positive end of a slot is too small to make a connection. I had to use a button adapter PCB.

26800 cells

I found that unprotected flat top QB26800 cells with a length of 81.1mm fit comfortably into every second slot of the XTAR VC8S and they charged successfully!

26800 cells are not officially supported because the XTAR VC8S supports up to 80mm and some 26800 cells are longer than 80mm.

The XTAR VC8S officially supports certain Li-ion cells with a length between 30mm and 80mm. However, I measured 29.3mm to 81.1mm between the tips of each slot. So there is a little bit more space available for slightly shorter and slightly longer cells (at least on the sample that I received).

Here is a video demonstrating a 26800 cell being inserted and removed:

Four 26800 cells can be charged at a rate of 2A by putting two cells in slots 1-4 and two cells in slots 5-8.

XTAR VC8S 26800-1

Two 26800 cells can be charged at a rate of 3A when one cell is in CH1-CH4 and another cell is in CH5-CH8.

XTAR VC8S 26800-2

Store and Grade modes also work as expected with 26800 cells but it will take a long time to measure the capacity of a cell with the Grade mode when the discharge current is 300mA.

XTAR SC1 Plus vs XTAR VC8S (which one gets hotter?)

Up until now, I have been using an XTAR SC1 Plus to charge my 26800 cells. I’m pretty happy that the VC8S has been able to charge four 26800 cells at the same time.

One thing that I noticed with the SC1 Plus is that it gets really hot!

I decided to charge one 26800 cell in an XTAR SC1 Plus and charge two 26800 cells in the XTAR VC8S at 3A to see which charger gets hotter.

I measured the maximum surface temperature of the chargers and cells with an infrared thermometer. Each cell started at 3.6V and was charged at a rate of 3A. The room temperature was 24.4 C.

Minutes XTAR SC1 Plus XTAR VC8S
02:00 30.7 C 29.9 C
04:00 35.7 C 30.8 C
08:00 42.4 C 32.4 C
16:00 44.9 C 33.4 C
26:00 52.3 C 33.6 C
32:00 55.2 C 34.6 C

The XTAR VC8S was much cooler compared to the XTAR SC1 Plus while charging two 26800 cells at 3A.

Power supply

I checked compatibility with the following power supplies:

Power supply USB Type Protocol Does it charge?
PinePower Desktop USB-C PD Yes
PinePower Desktop USB-A QC Yes
XTAR USB-C PD 45W Power Adapter USB-C PD Yes

Conclusion

The XTAR VC8S is an awesome upgrade over the VC8!

All eight slots can now be used for Store and Grade modes.

The termination voltage has mostly been between 4.18V to 4.20V while charging Li-ion cells. I am pretty happy with that!

There was one case where a protected 18350 cell was 4.139V after it had finished charging. I had left it on the charger for over ten hours and it may have slowly discharged.

My good quality Li-ion cells with a low internal resistances seem to terminate close to 4.20V.

The maximum discharge current is 300mA. It would be nice if the VC8S had big heatsinks and a fan so that it could have a 1A discharge current.

I am a bit fussy with how I charge my Ni-MH cells. It would be nice if the charging current could be adjusted at 0.1A steps from 100mA to 1A. The VC8S defaults to 0.5A for 1.2V Ni-MH cells and this cannot be adjusted.

The slot length was a nice surprise. It is just long enough to fit an unprotected 26800 cell. This is great for flashlight enthusiasts with a stack of 26800 cells!

I have a few XTAR SC1 Plus single cell chargers and they exceed 55 C when I charge a 26800 cell at 3A. It is nice to see that the VC8S remains cooler at around 35 C while charging two 26800 cells at 3A.

The user interface is simple enough to learn but it would be even better if the mode and the current could be selected for each individual slot. The slots are controlled in two groups of four slots. I can change the mode and current for slots 1-4 and slots 5-8 but I can’t change the mode and current for individual slots.

The VC8S is what the VC8 should have been originally. I am pretty happy with it. I can fill up the eight slots with Li-ion cells and get them to 3.6V for long term storage.

Pros:

  • Good build quality.
  • All eight slots can be used for Store and Grade modes.
  • Charge two slots at 3A, four slots at 2A and eight slots at 1A.
  • The charger did not get very hot while in use.
  • Four 26800 cells fit (unofficially).
  • LiFePo4 cells can be charged with the Store mode.

Cons:

  • Slots are controlled in two groups of four slots.
  • Charge current for 1.2V Ni-MH cells is not adjustable (500mA).
  • Slow discharge current (maximum of 300mA).
  • Does not support XTAR’s 1.5V Li-ion cells.

Price

The XTAR VC8S KIT is US$59.90 from xtardirect. This does not include a power adapter.

The XTAR VC8S SET is US$75.90 from xtardirect. There are a few different sets available with power adapters for certain countries.

Product page

XTAR VC8S KIT on xtardirect
XTAR VC8S SET on Amazon (affiliate link)
XTAR VC8S on xtar.cc