XTAR MX4 Charger

Specifications

Brand/model XTAR MX4
Channels 4
Input USB-C 5V 2A
Cut-Off Current ⩽100mA
Operating Temperature 0-40℃
Review date May 2024
Battery Type Constant Charge Current Cut-Off Voltage
3.6/3.7V Li-ion 1Ax2 / 0.5Ax4 4.2±0.05V
1.5V Li-ion 0.5Ax4 N/A
3.2V LiFePO4 1Ax2 / 0.5Ax4 3.65±0.05V
1.2V Ni-MH 0.5Ax4 1.45±0.1V

Introduction

The XTAR MX4 (Mini Mixer) can take a mix of four 1.2V Ni-MH, 1.5V Li-ion and 3.6/3.7V Li-ion batteries and charge them at the same time. There is also a special LiFePO4 Charging Mode for charging 3.2V LiFePO4 batteries.

The LC4, BC4 and BC8 chargers from XTAR are capable of charging 1.2V Ni-MH and 1.5V Li-ion batteries but those chargers do not support charging 3.6/3.7V Li-ion and 3.2V LiFePO4 batteries.

The XTAR MX4 helps fill that gap!

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 MX4 comes in a white and blue box with XTAR branding.

XTAR MX4 packaging-1 XTAR MX4 packaging-2

XTAR MX4 packaging-3 XTAR MX4 packaging-4

The following was included in the box:

  • XTAR MX4
  • USB-A to USB-C cable
  • User manual

XTAR MX4 accessories XTAR MX4 user manual

XTAR MX4 user manual XTAR MX4 user manual

Dimensions and weight

Dimensions

I took the following measurements using a digital caliper.

Measurement Unit (mm)
Charger height 27.55
Charger width 98.58
Charger length 100.18
Shortest cell length 30.4
Longest cell length 72

Weight

I took the following measurements using a digital scale.

Weight Unit (g)
XTAR MX4 95

It feels lightweight!

Battery compatibility

The following cells are supported:

Battery Type Sizes
1.2V Ni-MH AAA, AA, A, SC
1.5V Li-ion AAA, AA
3.6/3.7V Li-ion, 3.2V LiFePO4 10440, 14500, 16340, 18350, 18500, 18650, 18700, 20700, 21700 (unprotected)

I needed to balance a flat top 10440 cell perfectly to get it to make contact with a positive terminal and charge.

A 18350 cell with a recessed top was able to charge successfully.

A flat top 26650 cell was almost too wide to make contact with the positive terminals in the second and third channels but it charged successfully.

User interface

The XTAR MX4 is simple to use. You can simply select a charing mode and insert a battery (in the correct orientation).

There is a switch on the side to select:

  • LiFePO4 Charging Mode
  • Standard Charging Mode (Ni-MH/Li-ion)

XTAR MX4 closeup-switch

1.2V Ni-MH and 1.5V Li-ion cells can be charged in either LiFePO4 Charging Mode or Standard Charging Mode.

You must select LiFePO4 Charging Mode when charging 3.2V LiFePO4 cells and Standard Charging Mode when charging 3.6/3.7V Li-ion cells.

There are charging status indicator LEDs above each channel.

XTAR MX4 green XTAR MX4 red

The charging status indicator LEDs may be red, orange or green. Orange looks more like yellow.

Standard Charging Mode

When you connect a USB cable to supply power to an empty XTAR MX4, the LEDs will change from a Solid Red to a Solid Green to indicate that it is in the Standard Charging Mode and it is ready.

Battery Type LED Light Status Expected Time
1.2V Ni-MH Flashing Red Battery Recognition Less than 10 minutes
1.2V Ni-MH Solid Red Charging
1.2V Ni-MH Solid Green Charging Complete
1.5V Li-ion Flashing Red Battery Recognition Seconds
1.5V Li-ion Solid Red Charging
1.5V Li-ion Solid Green Charging Complete
3.6/3.7V Li-ion Flashing Red Battery Recognition Seconds
3.6/3.7V Li-ion Solid Red Charging
3.6/3.7V Li-ion Solid Green Charging Complete

LiFePO4 Charging Mode

When you connect a USB cable to supply power to an empty XTAR MX4, the LEDs will change from a Solid Orange to a Solid Green to indicate that it is in the LiFePO4 Charging Mode and it is ready.

Battery Type LED Light Status Expected Time
1.2V Ni-MH Flashing Red Battery Recognition Less than 10 minutes
1.2V Ni-MH Solid Red Charging
1.2V Ni-MH Solid Green Charging Complete
1.5V Li-ion Flashing Red Battery Recognition Seconds
1.5V Li-ion Solid Red Charging
1.5V Li-ion Solid Green Charging Complete
3.2V LiFePO4 Green to Orange Battery Recognition Seconds
3.2V LiFePO4 Solid Orange Charging
3.2V LiFePO4 Solid Green Charging Complete

If a LiFePO4 cell is under-voltage, the battery recognition/activation time might take 10 minutes.

Please note: I have not tested charging a 3.2V LiFePO4 cell.

I tried charging 3.6/3.7V Li-ion cells in LiFePO4 Charging Mode and the LED quickly went from orange to green to indicate that charging was complete.

Charger in use

There are four channels with sliders to allow short and long batteries to fit.

The two outer channels are slightly wider compared to the two inner channels. That said, I was able to fit four 21700 cells side-by-side.

XTAR MX4 front XTAR MX4 p45b

There is an image of a little battery in each channel to let you know which way a battery should be inserted.

The sliders all slide smoothly when inserting batteries.

XTAR MX4 closeup-slots

The negative terminals have notches while the tops of the positive terminals act like notches. It would be better if the positive terminals had bigger notches to support cells with deeply recessed flat tops.

The USB-C port for supplying power to the charger is pretty close to the bottom. Most of my USB-C cables fit. You might find that an oversized USB-C plug could result in the charger being slightly raised off the ground.

XTAR MX4 closeup-usb

There are five ventilation holes on the bottom of the charger.

XTAR MX4 back

Four plastic feet on the bottom help with ventilation. Rubber feet might do a better job of preventing the charger from sliding around on a smooth surface.

Tests

I have measured the voltage, current and temperature of various Ni-MH and Li-ion cells while charging them in the XTAR MX4.

DISCLAIMER: My results may not be very accurate because I have not calibrated the two ANENG AN9002 Digital Multimeters that I used for measuring the voltage and current. A 500mA charging current might end up being read as 450mA or 550mA. There may also be gaps in the data where Bluetooth connectivity has dropped. I restarted tests where too much data was lost.

Charge CH1 3.6/3.7V Li-ion #1

xtar-mx4-charge-ch1-li-ion-1

CH1: Sanyo NCR81650GA 18650 Li-ion 3500mAh (flat top)

Voltage CH1 CH2 CH3 CH4
Start 3.094
Finish 4.144

xtar-mx4-charge-ch1-li-ion-1

The XTAR MX4 charged a 3.7V Li-ion cell at a rate of 1A for about 2 hours 30 minutes before reducing the current and finally completing at 5 hours.

The cell may have had a high internal resistance. I measured a voltage of 4.144V about 20 minutes after taking the cell out of the charger.

Charge CH1 3.6/3.7V Li-ion #2

xtar-mx4-charge-ch1-li-ion-2

CH1: Molicel P45B 21700 Li-ion 4500mAh (flat top)

Voltage CH1 CH2 CH3 CH4
Start 2.860
Finish 4.161

xtar-mx4-charge-ch1-li-ion-2

There was a 200mA trickle charge (TC) for the first 20 seconds where the voltage increased from 2.86V to 2.91V. The charging current then increased to 1A. After 4 hours 10 minutes the current dropped and the voltage became constant. This is the TC-CC-CV charging method in action.

I measured a voltage of 4.16V about 20 minutes after taking the cell out of the charger. This is better. It is closer to 4.20V.

Charge CH1 1.5V Li-ion #1

xtar-mx4-charge-ch1-1-5-li-ion-1

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

Voltage CH1 CH2 CH3 CH4
Start 1.104
Finish 1.515

xtar-mx4-charge-ch1-1-5v-li-ion-1

XTAR kindly included two blue 1.5V Li-ion cells to test.

These 1.5V Li-ion 2500mAh cells are about 1.515V when full and about 1.10V when they need to be charged.

XTAR claim that these cells have a built-in charger that uses a TC-CC-CV charging method.

The graph shows the MX4 providing 5V 0.4A input to the cell.

To verify whether the cell has a TC-CC-CV charging method, I would need to disassemble a cell. I have opted not to do this.

Charge CH1 1.5V Li-ion #2

xtar-mx4-charge-ch1-1-5-li-ion-2

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

Voltage CH1 CH2 CH3 CH4
Start 1.101
Finish 1.509

xtar-mx4-charge-ch1-1-5v-li-ion-2

I tested a green XTAR 1.5V Li-ion cell with a built-in battery status indicator LED. The blue XTAR 1.5V Li-ion cell also has an LED but the white XTAR 1.5V Li-ion cell does not have an LED.

The green cell took slightly less time to charge compared to the blue cell. The 0.4A current looks more stable here.

Charge CH1 1.2V Ni-MH #1

xtar-mx4-charge-ch1-ni-mh-1

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

Voltage CH1 CH2 CH3 CH4
Start 1.195
Finish 1.418

xtar-mx4-charge-ch1-ni-mh-1

I charged a relatively new LADDA 1.2V Ni-MH AA battery in the XTAR MX4.

The MX4 started with a 200mA pulse current and continued to charge with a 500mA pulse current. After 5 hours 40 minutes, it appeared to have 0dV or -dV detection to change to a stage where it spends another 2 hours topping the cell off.

The top off current looks a bit high at first glance but the average could be 50mA instead of 500mA. I should figure out how to plot the average current so that the graphs are more useful.

Charge CH1 1.2V Ni-MH #2

xtar-mx4-charge-ch1-ni-mh-2

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

Voltage CH1 CH2 CH3 CH4
Start 1.190
Finish 1.462

xtar-mx4-charge-ch1-ni-mh-2

Bluetooth connectivity to one of my digital multimeters dropped out for a few minutes around 7 hours 40 minutes so there’s a small gap with the voltage measurements.

The eneloop pro AA cell is a bit older compared to the LADDA cell that I tested. The charging profile looks very similar.

The algorithm that the XTAR MX4 uses for charging Ni-MH cells looks very similar to the algorithm used by the XTAR VP4 Plus Dragon:
https://lygte-info.dk/review/Review%20Charger%20Xtar%20VP4%20Plus%20Dragon%20UK.html

Standby drain

I measured the standby current with a UNI-T UT139C Digital Multimeter while power was disconnected from the XTAR MX4. I did this to figure out whether the charger would slowly discharge a battery over time if left in it with power disconnected.

Cell Standby current
Ni-MH 5 µA
1.5V Li-ion 3.8 µA
3.7V Li-ion 4 mA

You may want to remove a 3.7V Li-ion cell when it has finished charging so that it does not discharge over time. XTAR recommends removing the cell promptly after it has been fully charged.

Power supply

I checked compatibility with the following power supplies:

Power supply USB Type Protocol Does it charge?
Apple 61W Power Adapter USB-C PD Yes
PinePower Desktop USB-C PD Yes
PinePower Desktop USB-A QC Yes
PinePower Desktop USB-A Yes
XTAR USB-C PD 45W Power Adapter USB-C PD Yes

It’s always nice when I don’t have to find a specific power supply for a USB-C device to work!

Conclusion

The XTAR MX4 is a pretty good budget charger for charging 1.2V Ni-MH, 1.5V Li-ion, 3.6/3.7V Li-ion and 3.2V LiFePO4 batteries. Please note: I have not tested charging a 3.2V LiFePO4 cell.

The charger appears to be using an advanced TC-CC-CV charging algorithm for 3.6/3.7V Li-ion cells.

I found that charging completes around 4.15V when charging 3.6/3.7V Li-ion cells. I had hoped that they would be closer to 4.20V. To be fair, it is within the advertised specifications (4.2±0.05V).

I recommend the XTAR MX4 if you are hoping to consolidate the number of chargers that you have into one and standardising on using USB-C for input.

Pros:

  • Simple to use.
  • Batteries slide smoothly into a channel.
  • Multiple battery chemistries are supported.
  • The top of the positive terminals sticks out slightly like a notch.
  • There is a notch on the negative terminals to help with connectivity.

Cons:

  • Big notches on the positive terminals would improve connectivity with batteries that have deeply recessed tops.
  • There is no display to see what the voltage, current, internal resistance and capacity is.

Price

The XTAR MX4 is AU$20.98 on xtardirect.com and AU$23.90 on amazon.com.au at the time of writing.

Product page

XTAR MX4 at xtar.cc
XTAR MX4 at amazon.com.au (affiliate link)
XTAR MX4 at amazon.com (affiliate link)
XTAR MX4 at xtardirect.com

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