Charger Efest Xblack





Efest has been building a line of chargers from single cell to four cell with fixed and variable current, this is a very simple charger with one slot and one current.



I received the charger in a white cardboard box without any marking.



In the box is the charger and a power supply. The power supply is a universal voltage (100-240VAC 50/660Hz) with 1A output current.



The charger is powered from 12 volt or from USB. The supplied power supply uses the 12 volt input.



The slider for the battery works acceptable and can accept batteries from 31mm to 71mm.
The charger uses a red led to show when it is charging (led flashing) and when it is finished (led steady).




The charger can handle 70 mm long batteries including flat top cells.
The charger uses 1A current, i.e. it cannot handle normal ICR batteries in smaller sizes, only IMR batteries.



Measurements

• When not connected to power it will discharges with up to 1.5mA
• When connected to power it will discharge with 0.04mA.
• The charger will not restart charging if the voltage drops.
• Reinsertion of battery or power cycling will restart charging, but the led might not start flashing.
• Led will flash slowly while charging.
• Led will be steady when battery is charged.
• The charger starts with 0.4A charging at 0 volt, but if the voltage does not raise about 0.3V the led will start fast flashing.

I do not use my usual scale on the curves, because the charger overcharges I uses a higher maximum voltage



The charger uses constant current at 1A and this means that it uses a way to high charge voltage. This is not very good.
This high voltage is unavoidable with the charging algorithm used (CC).




The same problem is present with other battery capacities.



The charger uses about 0.45A from 12 volt when charging.



When charging from usb the charger uses about 1A and it cannot charge with the full current when the battery is nearly full.



M1: 33,4°C, M2: 38,5°C, HS1: 40,9°C
The charger does get a bit warm, but the battery is not heated much.


Testing with 2500 volt and 5000 volt between mains and low volt side, did not show any safety problems.



Conclusion

Charging with a constant current is not a good way to charge LiIon batteries and with 1A charge current the voltage is way to high.
The electronic is too cheap and it affects the function, I cannot recommend this charger.



Notes

The charge was supplied by Efest for review.

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