XTAR VX4 Review

XTAR kindly sent the VX4 for review along with XTAR branded 16340, 18650 and a 26650 cells.

The VX4 is a larger version of the MX4 except it has a display and an additional Grade mode.

It can charge and grade: 1.5V Li-ion, 3.6V Li-ion, 3.2V LiFePO4 and 1.2V Ni-MH.

The terminals have notches that allow cells with slightly recessed tops (e.g. Vapcell F14 18350) to fit.

I was able to get three 26800 to fit side-by-side. The two inner slots are too narrow to comfortably fit four 26800 cells.

The charging current is selectable fot 3.6V Li-ion: 0.25 A, 0.5 A, 1 A, 2 A, 3 A. It’s not 3A per channel (it’s limited to 1A when there are 4 channels in use). The VX4 lowers the charging current as the voltage gets closer to 4.20V. I noticed charging terminate at 4.16V. We’ll soon find out when testing is complete…

The charging current is 0.5A for 1.2V Ni-MH.

The Grade mode has a 0.3 A discharge current for 1.5V Li-ion and 3.6V Li-ion. This could be pretty slow when grading a 6000mAh 26650 cell.

There is USB-C input. 12V 1.67A USB-C PD is recommended. The charging current might be limited otherwise.

13 of 16 tests:
Grade XTAR 1.5V Li-ion AA
Grade XTAR 3.6V Li-ion 16340 850mAh
Grade XTAR 3.6V Li-ion 18650 4000mAh
Grade Sanyo NCR18650GA 3500mAh
Grade NEXTORCH 16340 3.6V Li-ion 800mAh
Grade TrustFire 16340 3.7V Li-ion 650mAh
Grade XTAR 3.6V Li-ion 16340 850mAh
Grade XTAR 3.6V Li-ion 26650 6000mAh
Grade LADDA 1.2V Ni-MH 2450mAh
Charge XTAR 1.5V Li-ion AA
Charge XTAR 3.6V Li-ion 16340 850mAh
Charge XTAR 3.6V Li-ion 18650 4000mAh
Charge Sanyo NCR18650GA 3500mAh
Charge Molicel P45B 21700 3.6V Li-ion 4500mAh
Charge XTAR 3.6V Li-ion 26650 6000mAh
Charge LADDA 1.2V Ni-MH 2450mAh

Here’s a quick look at my testing setup:

I’ll post test results and more info as the review progresses.

Please let me know if you have any questions.

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Interested to see your tests. I have one on its way for a review, but I’ll link to reviews with more detailed technical tests than I’m able to perform.

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I should really start taking measurements on mine… :sweat_smile:

Looking forward to your review and will take it as an inspiration. :+1: :smiling_face:

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Here is my first test, Grade mode with a 1.5V Li-ion cell.

Grade CH1 1.5V Li-ion #1

CH1: XTAR AA 1.5V Li-ion 2500mAh (button top) (dark blue)

Measurement CH1 CH2 CH3 CH4
Start Voltage 1.510
Finish Voltage 1.509
Capacity (mAh) 2453

Before starting this test, I charged the 1.5V Li-ion cell, took the cell out, selected Grade mode, and put the cell back in.

The graph shows what the XTAR VX4 did while using Grade mode:

  • Charge the cell at roughly 4.9V 0.5A for a few minutes.
  • Discharge the cell at 0.3A for a 8 hours. A capacity of 2453mAh was measured (pretty good for a cell rated 2500mAh while the room was about 9 C).
  • Charge the cell again at roughly 4.9V 0.5A for 3 hours.
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How fast the Xtar recognizes that the cell was fully charged?

The VX4 spent 5 minutes 20 seconds charging the 1.5V Li-ion cell before it started discharging.

I had fully charged the cell in the VX4 in another room about 15-30 minutes earlier. I moved the charger and set it up to monitor with two Zoyi ZT-300AB digital multimeters.

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The VX4 doesn’t really recognize the battery was full. It waits until the charging controller in the battery stops drawing current.

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Grade CH1 3.6V Li-ion #1

CH1: XTAR 16340 3.6V Li-ion 850mAh (button top)

Measurement CH1 CH2 CH3 CH4
Start Voltage 4.176
Finish Voltage ?
Capacity (mAh) ?

The XTAR VX4 continued to discharge and charge the protected XTAR 16340 cell.

I suspect that the protection circuit of the cell may have Over Voltage Protection (OVP) where it temporarily cuts out at around 4.21V. The XTAR VX4 stops charging the cell. OVP of the cell resets. The XTAR VX4 detects the cell as a newly inserted cell and then it repeats Grade mode.

It sure would be nice to be able to limit the number of cycles to one… Only.

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That’s a bit of an issue if it doesn’t stop after one grading cycle. Hope the firmware can be upgraded!

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in a video I just saw, different chemistries were “graded” = capacity tested at the same time in the VX4 and all ended up with a “done” in the display …

the 1.5V Li-Ion and an NiMH were ready earlier and remained at the status “done”, while two 3,6V Li-Ion were charged for another 1 to 1.5 hours or so …

so there was no start of a new “Grade” cycle …

in case of TimMc’s experience there must have been a malfunction, for what reason ever …

I’ll use Grade mode for another 16340, 18650, 26650 and see what happens.

The graph above was my first attempt at Grade with a 3.6V Li-ion.

Did they mistaken the Grad. with a refresh program?

Would be nice you try that also with NiMH

Grade CH1 1.2V Ni-MH #1

CH1: LADDA AA Ni-MH 2450mAh (button top)

Measurement CH1 CH2 CH3 CH4
Start Voltage 1.433
Finish Voltage 1.452
Capacity (mAh) 2474

Grade mode worked properly with a Ni-MH battery. I’ll try again with a different Li-ion cell.

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But more than 8h for discharging an AA is really annoying.

Grade CH1 3.6V Li-ion #3

CH1: Sanyo NCR18650GA Li-ion 3500mAh (flat top)

Measurement CH1 CH2 CH3 CH4
Start Voltage 4.196
Finish Voltage 4.143
Capacity (mAh) 3320

Grade for an unprotected 18650 Li-ion worked ok.

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Does this mean that it didn’t continue to cycle the process…it stopped after one CDC cycle?

Yes. It stopped after one CDC cycle. The graph shows the charger sitting idle for 4 hours at the end.

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Ya mean I was supposed to look at the graph…??? :japanese_ogre:

Thanks though!

Curious that it didn’t stop on your first test run.

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Grade CH1 3.6V Li-ion #5

CH1: TrustFire 16340 3.7V Li-ion 650mAh (button top)

Measurement CH1 CH2 CH3 CH4
Start Voltage 4.194
Finish Voltage 4.138
Capacity (mAh) 684

Grade worked properly with a TrustFire 16340 Li-ion cell. The Charge-Discharge-Charge cycle stopped and it did not restart after an hour and a half.

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