Test/review of Efan Lux S4 LCD charger

Efan Lux S4 LCD charger

This is a analyzing charger from Efan (Eizfan), there is no buttons on it because it uses a color touchscreen for user interface.

I got the charger in a cardboard box, if has a good picture of the charger and specifications on the back.

The pack included the charger, a power supply, a mains cable, a manual and probes for internal resistance measurement.

The charger use 12V 5A power and the mains power supply is included. The probes for internal resistance is connected to the “IR TEST” socket when measuring IR. The DATA connector is for firmware upgrade

The charger shows a animation during power on.

This is the idle picture when no batteries are in the charger. When a battery is put in the battery symbol is selected and it is possible to press on it to select settings.

There are 3 settings screens, the first one for mode, the second for current.

And the last for chemistry

Pressing the “R” button will show the internal resistance measurement screen.

Some examples on charging/discharging screens, the curve is drawn while working and the horizontal scale will change as needed.

There is no indication of charge/discharge current, it must be inferenced from the slope of the voltage curve.

The probes for internal resistance measurement, they are not 4-terminal, but the circuit in the charger may eliminate the resistance in the connector.

The probes includes tip protectors

They are connected to the usb plug on the back of the charger.

And pressed against the battery ends to measure internal resistance.

The charger has a small fan, it is temperature controlled and starts when needed, but it is rather noisy.

The charger has the usual slider construction. It can handle from 33mm to 76mm, this is most common cells on the market.

32xxx and D do not really fit in the charger, but it may be possible to put them in.

Measurements charger

  • Power consumption when idle is 1.6 watt (The power supply uses 0.11 watt in idle).

  • Without power it will discharge a LiIon battery with about 0.5mA

  • Without power it will discharge a NiMH battery with about 0.1mA

  • A full LiIon battery will be charged with 0.6ma

  • Below 0.07V the charger will charge will report error

  • Up to 2V the charger assumes NiMH

  • Above 2V the charge assumes LiIon.

  • Charger will restart if battery voltage drops below 3.9V in 4.20V mode

  • The charger will restart when a battery is inserted or power is cycled.

  • The meter has a minimum readout of 0.5V

  • Up to 0.8V the meter is not very precise.

  • From 0.8V to maximum the meter is within 0.05V

  • The meter will never show above maximum battery voltage (3.60V, 4.20V, 4.35V)

Charging 4.2V LiIon

Current can be selected from 0.5A, 1A, 1.5A and 2A, default is 1A.

This is a nice CC/CV charge curve with termination at around 100mA.

Display shows 3084mAh and 3:58

Display shows 3071mAh and 3:56

Display shows 3106mAh and 5:25

The other 3 channels works the same way.

Display shows 3096mAh and 4:22

Display shows 2485mAh and 3:28

No problem with other capacities.

Display shows 2747mAh and 4:34

The old cell goes into CV mode fairly fast and also stops when the current is down to 100mA

Display shows 1940mAh and 5:13

Lower charge current means longer charge time and slightly lower charge voltage, the termination current is the same.

Display shows 3064mAh and 7:42

This old and worn down cell is handled as fine as possible with 100mA termination current.

Display shows 151mAh and 0:40

Same with this cell.

Display shows 688mAh and 1:52

The 1.5A setting is fine for 3000mA and larger cells, it will charge a bit faster than the 1A setting.

Display shows 3152mAh and 3:21

The charger can also charge with 2A, the termination current is 100mA. The charging is for high current cells and larger cells it is faster than 1A/1.5A, but there can be a long CV phase.

Display shows 3212mAh and 2:43

Charging a high current cell at 2A is faster, there the CV phase is fairly short.

Display shows 3024mAh and 1:44

The charger can charge 4 batteries at 2A

Display shows 3188mAh,3209mAh,3173mAh,2420mAh and 2:30, 2:26, 2:21, 2:06

It need about 4A from 12V to do it.

Display shows 3159mAh, 3241mAh, 3205mAh, 3151mAh and 3:04, 2:25, 2:19, 2:29

When charging 4x2A it do get a bit warm, especially the battery nearest the display.

M1: 48.1°C, M2: 43.6°C, M3: 41.0°C, M4: 39.0°C, HS1: 58.8°C

M1: 53.0°C, M2: 43.0°C, HS1: 64.6°C

The charger starts very slowly, this gives the user time to change mode or battery type.

It is possible to change current at any time during the charge.

Discharging 4.2V LiIon

Discharging is with a constant 0.5A current.

The charger will discharge to about 2.8V with a constant current, i.e. not PWM.

Display shows 2995mAh and 6:06

Display shows 3044mAh and 6:12

Display shows 3074mAh and 6:16

The other slots look similar.

Display shows 3085mAh and 6:14

With a fan in the charger it is no problem discharging 4 batteries.

Display shows 3070mAh ,3185mAh ,3149mAh ,3079mAh and 6:16, 6:29, 6:25, 6:17

M1: 39.7°C, M2: 35.2°C, M3: 32.7°C, M4: 30.9°C, M5: 46.2°C, HS1: 53.9°C

No PWM when discharging.

Capacity test 4.2V LiIon

A capacity test consist of charging the battery, discharging it and final charging it again. The discharge current is fixed at 0.5A, the two charge cycles can be selected from 0.5A, 1A, 1.5A and 2A, default is 1A

Display shows 3037mAh and 14:45

Charging 4.35V LiIon

Charging a 4.35V cell looks fine enough.

Display shows 2777mAh and 3:29

Charging 3.6V LiIon (LiFePO4)

Display shows 1185mAh and 1:43

Charging LiFePO4 also looks fine enough.

Display shows 508mAh and 1:16

Measuring Internal Resistance LiIon

The charger do not measure internal resistance in the slots, but uses an external probe.

The results looks fairly consistency but the values is not correct, especially the +100mOhm is way to low.

The measurement is done with two pulses, at the first pulse the display will show voltage a 0mOhm, at the next pulse the measured resistance will be shows.

It looks like a hardware bug with a initial 6A+ current draw and then dropping to around 1A. I will not expect this to affect the measurement.

Charging NiMH

Current can be selected from 0.5A, 1A, 1.5A and 2A, default is 0.5A. When charging starts the current is locked and cannot be changed.

The charging is terminated on voltage and then followed by a two hour trickle/top-off charge. The termination looks to be just before the temperature raises to signal full cell. The measured mAh is a bit on the low side.

Display shows 1525mAh and 2:11

Display shows 1483mAh and 2:08

Display shows 1536mAh and 2:12

All slots looks similar.

Display shows 1478mAh and 2:07

The Pro is charged the same way.

Display shows 2165mAh and 3:03

The Leise cell is filled completely (Temperature increases).

Display shows 2440mAh and 3:25

No surprise with the AAA

Display shows 589mAh and 1:42

The charger has no problem terminating at low charge current, because it uses voltage termination.

Display shows 1601mAh and 4:25

It can also charger NiMH at 2A, due to the measurement pauses the average current is a bit below 2A.

Display shows 1528mAh and 1:10

A full cell was not detected before it went to full charge current, but it is still a fairly fast detection. As usual it adds the two hour top-off charge.

Display shows 41mAh and 0:12

The charger can charge 4 NiMH with 2A each at the same time.

Charging at 4x2A requires about 2A from the power supply

Display shows 1514mAh ,1622mAh ,1564mAh ,1438mAh and 1:10, 1:14, 1:12, 1:07

There is not much heat when charging AA cells.

M1: 31.3°C, M2: 31.3°C, M3: 32.3°C, M4: 30.2°C, HS1: 41.9°C

M1: 40.2°C, M2: 30.0°C, HS1: 45.2°C

The charger has the same startup sequence as LiIon, but in addition it uses a low charge current for the first 10 minutes.

As is common with all NiMH chargers the current is turned off to measure the NiMH voltage.

It is the same at 2A.

The top-off/trickle charging is pulses

Each pulse is about 1 second wide with 20 second between pulses, this gives an average current of 100mA when using 2A charging. The current will scale with selected charge current.

Discharging NiMH

Discharging is with a constant 0.5A current.

The batteries are discharged to about 1.05V with a constant current.

Display shows 1847mAh and 3:34

Display shows 1770mAh and 3:25

Display shows 1862mAh and 3:36

All 4 slots looks similar.

Display shows 1758mAh and 3:24

M1: 32.2°C, M2: 29.6°C, M3: 29.1°C, M4: 29.0°C, M5: 37.8°C, HS1: 40.0°C

No pwm when discharging.

Capacity NiMH

A capacity test consist of charging the battery, discharging it and final charging it again. The discharge current is fixed at 0.5A, the two charge cycles can be selected from 0.5A, 1A, 1.5A and 2A, default is 0.5A

Display shows 1818mAh and 7:55

Measuring Internal Resistance NiMH

The charger do not measure internal resistance in the slots, but uses an external probe.

The measurement is fairly consistent, but I am not very impressed with the results here.

The measurement is done with two pulses, at the first pulse the display will show voltage a 0mOhm, at the next pulse the measured resistance will be shows.

These pulses looks fine enough.

Testing with 2830 volt and 4242 volt between mains and low volt side, did not show any safety problems.


This is a fairly advanced charger with discharge and capacity measurements and 3 LiIon chemistries. The color screen with touch works fine and may allow for updates later on. The charger shows all relevant data on the main screen, but only for one cell at a time.

Generally it is a good charger and analyzer, but capacity when charging NiMH (Discharge and capacity test is fine) and IR measurements are not reliable with the current software.


The charger was supplied by Efan for review.

Here is an explanation on how I did the above charge curves: How do I test a charger

Thanks for the review. That is one expensive charger.

Interesting charger, so thanks showing this and for your review :+1:

As always, wonderful and thorough review HKJ!

I’ve always wondered, what purpose does discharging NiMH and LiIon cells serve? I have NiMH and LiIon cells that are 5-10 years old and I’ve never discharged them and they’re still chugging along fine.

Primary purpose is checking the capacity of the cells. With NiMH you may also recover some capacity, especially if the battery has been unused for some time.

Thanks for that!

well, i was expecting good IR measurement at its price.

imo it’s not worth the money, i dont want fancy screen because i dont look at my charger more than 5 minutes

Thanks for the review.
Initially, I was very happy. I thought that finally the charger of my dream appeared. But I was wrong.
Beautiful appearance, good color screen, graphics, serious price …
All this creates a feeling of a professional and functional product.
You think - this is a powerful combine, the king of chargers.
But …
The discharge current is 0.5A. ONLY!!
Ahaha)))) This is so funny and stupid)).
No, I’m serious - I have not seen anything dumber. It’s like a delightfully beautiful Ferrari, which has only one gear and a motor from a Smart car.
You look at this sparkling sports car and you think - this is a powerful machine that is expensive and drives fast.
But then it turns out that this is a slow and useless car.

Ok, so what are top 26650/18650 chargers now? Can this be so called? One of the top?