Charger Xtar XP1



Xtar made many good chargers, this is a new small charger. It has a single channel and can charger both LiIon and NiMH batteries up to AA size.




It comes in a cardboard box with specifications on the back.



I got the charger, a manual and a usb cable.



The control panel has 3 leds and one button:
2 Leds to show selected current (0.25A or 0.5A).
1 leds to show charge status for the batteries (red=charging, green=done or no batteries).
The button will select charge current, when power is connected and a long press will activate cycling with a NiMH (Not with LiIon).



The power input is a micro usb connector, i.e. any usb power supply/charger can be used.



Xtar has a special label on, that makes it possible to check for counterfeig chargers.



The charger can handle both button top and flat top batteries, from 31mm to 52.8 mm (i.e. from CR123 up to AA size). The slider works very smooth.








The charger can handle 52.8 mm long batteries, including flat top cells. (See my Small LiIon comparison for length of different brands).



Measurements charger

• Charger uses a buck circuit, i.e. it uses less current from usb, than it charges with.
• When power is disconnected it will discharge 1.5 volt batteries with 20uA
• When power is disconnected it will discharge LiIon batteries with 60uA
• Will charge LiIon with 150uA after termination.
• Will charge 1.5 volt batteries with 10mA after termination.
• Will restart LiIon charge, if voltage drops below 3.90 volt.
• Will restart charge on power cycle and reinsertion of battery.
• Will detect at battery at 0.14 volt and start charging.
• At about 1.9 volt it will switch to LiIon charging.

This charger has a very good CC/CV curve, the termination current is slightly high.



My old 16340 is also charged fine.





250mA or 0.25A works just as good, just slower.



During startup the charger has a periode with low charge current, my guess it that it is used to detect battery type.



Increase in charge current is done with a slow ramp.



NiMH batteries




The charger does some pulsing while charging NiMH, it looks like the termination is a -DV termination.
When terminated the charger will trickle charge, this is a good idea with NiMH (But prohibited with LiIon)



Using 0.25A charge current is not a good idea for AA batteries, the charger has problems detecting when it is done.



With AAA batteries at 0.25A charge current, the termination if detected earlier, but it is still not perfect.



It takes 60 minutes to detect a full AA battery at 0.5A, not very good.



Holding the button down with a NiMH battery in the charger will start a refresh function, where the battery is first discharged, then charged.



The current selection is not used during discharge, only during charge.



With a NiMH battery in the charger, it stays at the low current for about 2 minutes, before going to full charge current.



During NiMH charge it will stop charging each other second, this is probably done to check the voltage.


Conclusion

This charger does a good CC/CV charging on LiIon and with 2 current settings it can handle a wide varity of small cell sizes.
The NiMH charging has some problems with termination, making the termination a bit more sensitive and only allow charging at 0.5A would probably be a good idea.

The charger is a very good LiIon charger and a acceptable NiMH charger.



Notes

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