Test/review of Xtar VC8

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HKJ
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Test/review of Xtar VC8

Xtar VC8
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A eight slot LiIon and NiMH charge with automatic current selection, it is USB powered, preferable from a QC supply.
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The charger was in a white cardboard with specifications on it.
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The box included the charger, a USB cable and a instruction sheet.
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The charger has a USB type-C input, the supplied cable is a USB-C to a old style USB-A connector.
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The charger has two displays and four buttons. It is two partly identical sections.
Button Mode/Disp.: This select between current, capacity and IR display, hold down to select grade and store function (Only first section).
Button Curr.: Selects maximum charge current, but the automatic detection will reduce this to what it decides is safe.
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During power on all segments are shown, when it changes to idle only the selected function is shown.
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Actual battery current, the charger is charging on slot #1 and still preparing for slot #3 & #4.
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Actual battery current.
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Capacity.
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Internal resistance.
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The charger has specifications on the back, with black text on black background.
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The connection are the common slider style that can handle from 32mm to 76mm, this means all batteries will fit.
supportedBatteryTypes
supportedBatterySizes
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Measurements charger


  • When not powered it will discharge a LiIon battery with about 2.2mA and NiMh with about 0.3mA
  • When powered the charge will charge with less than 0.6mA when finished.
  • Below 2V the battery is assumed to be NiMH, above LiIon.
  • Charger will restart if battery voltage drops below 3.9V.
  • Voltmeter is within 0.02V
  • Voltmeter will stop updating when charging stops.
  • Slot #1 & #8 has a 3A current setting.
  • All slots has .25A, 0.5A, 1A & 2A current settings.
  • Background light goes to low brightness after 60 seconds.
  • Power consumption when idle without batteries is 110mA from USB with backlight on full and drop to 77mA when brightness is reduced.

Charging LiIon
Some of my test was done with 5V and some with QC where the charger uses 9V. In some cases I manually selected the current, in other I let the charger do it. If there is a DC input current trace the charger has a 5V supply in other cases a QC charger is used for supply.
In all test I have test equipment connected between the battery and the charger (For the 8 battery test I only have equipment on one battery). It has a few mOhm resistance and some contact resistance.
Xtar%20VC8%20auto%20%28SA18650-33%29%20%231
A standard CC/CV charge curve, the charger decided to use 1A charge current. Termination current is around 170mA.
Display shows: 2958mAh 69mOhm
Xtar%20VC8%20auto%20%28SA18650-33%29%20%232
Display shows: 2956mAh 0mOhm
Xtar%20VC8%20auto%20%28SA18650-33%29%20%233
This time the charger used 0.5A charge current. There is no IR reading on the display.
Display shows: 3137mAh 0mOhm
Xtar%20VC8%20auto%20%28SA18650-33%29%20%234
Display shows: 3061mAh 82mOhm
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For this battery the selected current was 0.25A, this is rather low. There is no IR reading on the display.
Display shows: 2968mAh 0mOhm
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This battery has a fairly high internal resistance according to the charger.
Display shows: 2895mAh 128mOhm
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Display shows: 2861mAh 0mOhm
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Display shows: 3221mAh 0mOhm
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I selected 3A charge current to get a faster charging, but it did not work.
Display shows: 2866mAh 62mOhm
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Display shows: 2366mAh 143mOhm
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This time I got lucky and the charger decided to use 2A charge current.
Display shows: 2633mAh 57mOhm
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Display shows: 2913mAh 65mOhm
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Display shows: 2658mAh 49mOhm
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This old cell got 0.5A charge current and registered 245mOhm in internal resistance.
Display shows: 1748mAh 245mOhm
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Display shows: 2786mAh 119mOhm
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Display shows: 3201mAh 49mOhm
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The current selection can force the current down, here I have selected 0.25A and the charger uses it.
Display shows: 3025mAh 116mOhm
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A larger cell, this time I got the current up to 2A
Display shows: 2822mAh 53mOhm
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Display shows: 878mAh 246mOhm
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Here I charge 8 batteries with a QC supply and current selected to 2A, actual current is around 0.5A. This is very reasonable for a 9V 2A supply (Even a bit on the high side, it may have used lower rate on some batteries).
Display shows:
Capacity: 2618mAh, 3001mAh, 3552mAh, 3223mAh, 2909mAh, 2861mAh, 2956mAh, 3061mAH
Resistance: 90mOhm, 44mOhm, 31mOhm, 31mOhm, 32mOhm, 33mOhm, 30mOhm, 29mOhm
Temp7555
M1: 31.3°C, M2: 32.9°C, M3: 32.3°C, M4: 32.3°C, M5: 32.4°C, M6: 32.3°C, M7: 31.8°C, M8: 30.6°C, HS1: 39.5°C
Temp7556
HS1: 39.9°C
PowerOnLiIon
The charger needs about 12 seconds to turn on, some of the time is used to measure the internal resistance.
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The charger will discharge a full LiIon battery with about 2.2mA when not powered.
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The charger will did rather well with unstable supply.
Grading LiIon
A grading sequence consist of charge the battery, discharging it while measuring capacity and the charging it again. Due to the low currents it is done at it takes a lot of time to do. This function is only available on the first four slots.
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The battery is discharged to around 2.6V with a current of about 300mA
Display shows: 3024mAh
Xtar%20VC8%20Grad%20%28SA18650-33%29%20%232
Display shows: 3164mAh
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Display shows: 3056mAh
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Display shows: 3132mAh
Xtar%20VC8%20Grad%20%284xSA18650-33%29%20%231234
Display shows: 3075mAh, 3193mAh, 3176mAh, 3234mAh
Temp7609
M1: 44.5°C, HS1: 54.9°C
It looks like the heat from discharging is dissipated at the front of the charger, i.e. away from the batteries (Good).
Temp7610
M1: 34.6°C, M2: 36.8°C, M3: 37.1°C, M4: 34.3°C, HS1: 56.0°C
Storing LiIon
The store function will bring the batteries to a half charged state, this is the best way to keep batteries for long time storage (Keeping them at a cool place is also a very good idea). This function is only available on the first four slots.
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It can charger to half full.
Display shows: 3.70V
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But is can also discharge to half full.
Display shows: 3.68V
Charging NiMH
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This looks like a charging with -dv/dt termination or maybe 0dv/dt termination. The charger is fairly slow to terminate. There is no trickle charge.
Display shows: 2366mAh, 113mOhm
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Termination speed is better here and charge current is higher.
Display shows: 2134mAh, 64mOhm
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This is a rather fast charge at 1.5A (Current is 2A), with a good termination.
Display shows: 2143mAh, 57mOhm
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Again a low current charge with a slow termination.
Display shows: 2299mAh, 231mOhm
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Display shows: 2220mAh, 111mOhm
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Display shows: 1916mAh, 275mOhm
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Display shows: 2108mAh, 0mOhm
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Display shows: 2109mAh, 76mOhm
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The enelope pro that is a bit old was slow to termination and was more than fully charged, but at 0.5A the temperature raise was limited.
Display shows: 3320mAh, 116mOhm
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The Fujitsu charge was better and much faster.
Display shows: 2720mAh, 60mOhm
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Display shows: 3139mAh, 154mOhm
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Display shows: 804mAh, 113mOhm
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The full battery was stopped fairly quick for a -dv/dt charger.
Display shows: 147mAh, 60mOhm
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Display shows:
Capacity: 3606mAh, 2304mAh, 4201mAh, 1335mAh, 993mAh, 1347mAh, 603mAh, 2850mAh
Resistance: 63mOhm, 26mOhm, 28mOhm, 201mOhm, 39mOhm, 36mOhm, 32mOhm, 32mOhm
The first battery was serious overcharged and one some of the other there was some very low capacities: 1335mAh, 993mAh, 1347mAh, 603mAh was my batteries not empty or have they lost that much capacity? I put them on a SkyRC MC3000 charger and discharged them, that got me: 1287mAh, 1066mAh, 1379mAh, 626mAh. They must have been empty when I started, but have they lost capacity? I did a test on the MC3000 and all batteries was 1900mAh +/-15mAh, i.e. no significant capacity loss.
In another similar test I did the result was 2307, 3194, 3903 3273, 1044, 3301, 568, 3741
I.e. more overcharged batteries, but also some undercharged.
In these test I only have measuring equipment on slot #1, all the other are without any extra stuff between batteries and charger.
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What about using a QC for power?
Display shows:
Capacity: 2173mAh , 2011mAh, 2435mAh, 2230mAh, 1956mAh, 2288mAh, 596mAh, 2179mAh
Resistance: 57mOhm, 27mOhm, 28mOhm, 26mOhm, 31mOhm, 30mOhm, 30mOhm, 27mOhm
The result is much better, but not perfect, one battery did fail with only 596mAh.
Temp7546
M1: 27.8°C, M2: 28.9°C, HS1: 30.6°C
PowerOnNiMH
The charger uses the same time as for LiIon, before it starts on the charging. After a few minutes it may increase the current.
Charge%20Solar%20NiMH
The charger handled unstable voltage considerable very nicely with NiMh.
Grading NiMh
A grading sequence consist of charge the battery, discharging it while measuring capacity and the charging it again (The last part do not really work here). Due to the low currents it is done at it takes a lot of time to do. This function is only available on the first four slots.
Xtar%20VC8%20Grad%20%28eneloop%29%20%231
The batteries are discharged to about 0.8V
Display shows: 2022mAh
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Oops, the first charging is bad and this means the capacity is wrong.
Display shows: 1521mAh
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This test was done with a already charged battery and it got to the discharge part faster.
Display shows: 2038mAh
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Again with a full battery, but I am missing the -dv/dt part of the first charge curve.
Display shows: 2004mAh
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Grading four batteries at a time worked fine.
Display shows: 2045mAh, 2068mAh, 2063mAh, 2039mAh
Temp7619
HS1: 39.5°C
Temp7620
M1: 29.5°C, M2: 30.4°C, M3: 30.6°C, M4: 29.3°C, HS1: 38.4°C
Storing NiMH
Often NiMH is best stored fully charge, but this function will discharge them partially. I could not use it on discharged batteries. This function is only available on the first four slots.
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Display shows: 1.32V
Internal resistance
With 8 slots I did not want to use my detailed test, instead I checked the IR of a LiIon and a NiMH batteries with my own 4 terminal equipment, before and after measuring them on the charger.
IRLiIon
When averaging all slots I got 15mOhm
My test got 25mOhm – 30mOhm, depending on if calculated when turning current on or off or before or after the test on the charger.
IRNiMH
When averaging all slots I got 21mOhm
My test got 28mOhm – 32mOhm, depending on if calculated when turning current on or off or before or after the test on the charger.
There is some variation in the charger result, but it is in the correct range for the tested batteries.
Conclusion
With 8 channels this charger can get many LiIon charged fairly fast, without using a high current or a few cells fast using a high current (If the IR of the cells are low). The charger can also analyze batteries, but only on four slots.
In this charger the automatic current selection limits maximum selectable current, it is a good safety feature, but I am not really in favour of this automatic current selection, it is way to unpredictable (An it is even worse in my testing setup, due to extra contact resistance).
The charger did not do very well on NiMH. The recorded tracks are fairly fine, but the 8 cell tests are not. I do not like seeing my empty eneloop needing between 600mA and 4000mAh to be fully charged.
The storage function is fine for LiIon, but not for NiMH.
The LiIon part of the charger gets a good rating, but the NiMH rating is only acceptable.
Notes
The charger was supplied by a Xtar for review.
Here is an explanation on how I did the above charge curves: How do I test a charger

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

specialk
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Thanks for the review. My VC8 is being delivered today.

bmengineer
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Can this be powered from a USB-C power supply?

Find all my reviews of flashlights and more gear at www.bmengineer.com

HKJ
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bmengineer wrote:
Can this be powered from a USB-C power supply?

Yes, but it use QC at 9V for power.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/

Fwhomeboy
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specialk wrote:
Thanks for the review. My VC8 is being delivered today.

How much is it? I must have missed that part.

The New Guy

specialk
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I got it from amazon.ca it would probably be a lot cheaper if you get it from here https://liionwholesale.com/products/xtar-vc8-battery-charger-wholesale-d...

Fwhomeboy
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specialk wrote:
I got it from amazon.ca it would probably be a lot cheaper if you get it from here https://liionwholesale.com/products/xtar-vc8-battery-charger-wholesale-d...

Thanks

The New Guy

whatsthepoint
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Nice x8 charger if using with for Li_ion.I wonder how it stacks up when compared to the Efest LUC V8 that costs about 40% more.

When ordering batteries and chargers check and compare the delivered price.

Shipping charges vary,sometimes a lot, between the sites that are frequently mentioned in forum threads.

never underestimate the power of stupid people in large groups

specialk
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This review shows it has a very dim display in real life compared to online advertising photos https://www.e-cigarette-forum.com/threads/the-efest-luc-v8%E2%80%99s-dis...

d_t_a
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Great review and comprehensive testing.

I'm wondering, what might be a possible explanation for the NiMh batteries failing to get charged properly -- either overcharged, or not charging to full (not even half-full for some of them). Could it be contact resistance issue, or the specific VC8 sample unit has a factory defect?

Would like to hear what Xtar has to say about the issue (I think it's a definite flaw to have overcharged and undercharged NiMh if the above (overcharge/undercharge) happens erratically)..

~~~~~

Also, I notice that 3000mA charging current (display) didn't seem to work on your testing...

While I don't have a way to test 3000mA charging current on my VC8, I notice that when the display shows 3000mA charging current, power consumption on the USB side is higher than 2000mA charging current, so I'm assuming the 3000mA charging current is working normally. Unfortunately I don't have more equipment for testing other than my USB meters..

 

VC8 slot1 charging at 3000mA (manually selected current) ; USB power consumption 9v @ 1.6A ~ 14.5watts

 

Xtar VC8 slot 8 charging at 3000mA (manual selection) ; USB power consumption 9v @ 1.6A ~ 14.7watts

 

Xtar VC8, slot 8 charging at 2000mA (manually selected), USB power consumption 9v @ 1.06A ~ 9.7watts

specialk
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Last week on my Xtar VC4s I was charging 4 eneloops and one of them only charged to 596mah, it was probably on the 3rd or 4th slot. I’ll probably only charge NiMH batteries only on my Maha 800s, Gyrfalcon all44 or xtar Sv2, which all has never let me down.

whatsthepoint
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specialk wrote:
This review shows it has a very dim display in real life compared to online advertising photos https://www.e-cigarette-forum.com/threads/the-efest-luc-v8%E2%80%99s-display-batch-1-and-imate-r4%E2%80%99s-leds-are-too-dim.920163/[/quote]

Already asked about display

http://budgetlightforum.com/comment/1635545#comment-1635545

never underestimate the power of stupid people in large groups

d_t_a
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(for correction) In the round cell charger index table, the “minimum charge current” listed for the VC8 is 0.5A, it should be 0.25A.

https://lygte-info.dk/info/roundCellChargerIndex%20USBIn%20UK.html

I’m not very sure if the “Slot” column, indicated is 8 (2), indicating 8 slots but only 2 slots can use max size battery (I would presume 26650-size or maybe “D” size battery?), if placing 4 batteries alternately, wouldn’t the VC8 accommodate up to 4 slots “max size” battery?

HKJ
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d_t_a wrote:
(for correction) In the round cell charger index table, the “minimum charge current” listed for the VC8 is 0.5A, it should be 0.25A.

https://lygte-info.dk/info/roundCellChargerIndex%20USBIn%20UK.html

I’m not very sure if the “Slot” column, indicated is 8 (2), indicating 8 slots but only 2 slots can use max size battery (I would presume 26650-size or maybe “D” size battery?), if placing 4 batteries alternately, wouldn’t the VC8 accommodate up to 4 slots “max size” battery?

Thanks, I have fixed my table. The photos with batteries in the charger shows how large batteries it can handle.

My website with reviews of many chargers and batteries (More than 1000): https://lygte-info.dk/