[HKJ]

Charger NiteCore UM10





Nitecore has been known for the i2 and i4 chargers for a long time, but lately they have expanded their range with D2, D4, UM20 and this UM10. This charger is a simple one channel usb powered charger, it does also have a usb output, but is not a power bank.





The charger is sold in a blister pack, making it very easy to see it.



There is not much contents in the package: The charger, a usb cable and a instruction sheet.



On the back of the charger is the micro usb power input and a switch to select priority, i.e. where does the power go: to usb output or to charging batteries.



The charger has a display with background light. While charging the bars are animated. With my 3100mAh batteries the percent display starts at 8%.
The background light works but is not very good.



When something is connected to the usb output a usb symbol will be shown on the display.




The slots uses the usual construction and the slider is very smooth. They can handle batteries from 30mm to 69.3 mm long.
That excludes a few of the longest batteries.
The rear spring is used to select between 0.5A and 1A charge current.



The bottom of the charger with the usb cable wound around it.



The output usb connector is hidden beneath the bottom of the charger.





The specifications also list 10440, but the charge current is too high for them, except for IMR types.
The charger can handle 69.4 mm long batteries, including flat top cells.



Measurements

• Below 1.2 volt on the batteries the charger reports 0% and will only charge with a few uA.
• Between 1.2 and 2.5 volt the charger will charge with about 100mA
• Above 2.5 volt regular charge current will be applied.
• Charger will not restart if voltage drops and percent is frozen at 100%.
• Charge will restart charging after power loss, or battery insertion.
• When not connected to power it will drain about 0.05mA from a battery
• When charging is finished the charger will drain the battery with about 0.02mA.
• The charger will stop charging if usb voltage drops below about 4.4 volt.
• Percent scale: 1%<2.5V, 8%=2.6V-3.4V, 12%=3.5v, 33%=3.7V, 80%=4.0V, 96%=4.1V

Charging



A 18650 battery is charged with 0.8A and the charge is a nice CC/CV curve. When the battery is nearly full the charge will oscillate a bit, before terminating the charge.
There is not much of a temperature raise during charge.



This battery is showing its age, but the charger handles it fine.



The 3400mAh is a bit slower to charge.



My old 16340 cell is also handled without any problems.



The shorter battery is charged with about 0.4A.



The 14500 is also charged with 0.5A.



Using a falling voltage as supply it can be seen that the charger reduces current at about 4.5 volt and turns off charging at about 4.4V.



With 1ohm in series with the usb voltage the charging looks fairly normal, except that it cannot maintain full current.



M1: 36,0°C, M2: 34,7°C, M3: 31,0°C, HS1: 48,3°C
The charger keeps the batteries cool during charge.



The charger is very fast to start, only 0.5 second.



It pauses the charge to measure the voltage, i.e. it uses a simulated CC/CV charge.



The 0.5A charge is done by reducing current, there is no pwm.



Here I have zoomed in on the measure pulse, it is only slightly more than 1/800 second.



USB output

I did not do full test of usb output, because it failed

• Usb output is not a power bank, but a pass through connection
• When usb output is used the switch is used to decide between stop charging batteries or turn usb output off when voltage is low.

Doing the falling voltage with 0.5A load connected to usb output and switch in "usb" position.
Here the charging is stopped first (The animated bars stop animating on the display). When the voltage is to low the usb output is also turned off.



Same as above, but this time with switch in "Battery" position.
The first thing that is turned off is the usb output, then it reduces charge current and when the voltage is to low stops charging completely.



Conclusion

This is a single channel usb charger with automatic current select and a simulated CC/CV charge profile. It has a usb pass through connector, making it possible to charge a battery and a phone without moving wires around. With the switch it is possible to select what get charged first: battery or phone.

The automatic charge current selection is nice, but will select low current when not needed (Like 18500).

I know a couple of times where I would have liked the pass through function, but I would usual also like a power bank function at the same time.

During test the usb output died and I am not aware of doing anything to the charger that could kill this function.

It is a good charger (If it works), but I wonder how useful the pass through function is and it has to be made more robust.



Notes

The charger was supplied by a Nitecore for review when the usb output died on it I bought another one where I did get some of the usb measurement before it died and on this charger 0.5A charge current did not work.

Nitecore has made a video explaning the function of the charger/usb output.

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