Basen BO-2





This is a fairly simple usb powered dual cell LiIon charger from Basen.



The charger arrived in a cardboard box with lots of specifications on it.



The pack contained the charger, usb cable and instruction sheet in Chinese and English.



The charger is powered usb.



The user interface is one button and a couple of leds. The button will change between the 3 different charge current with a press.



All leds.



Charging one battery, it is nearly full, the top bar is flashing.



There is specifications and approval marks on the back.



The charger uses the typical slider construction, it can handle batteries from 28mm to 70mm.







The charger can handle 70mm long batteries, inclusive flat top cells, this means most protected cells.



Measurements charger

• LiIon will be discharged with 0.1mA when power is off.
• LiIon will be discharged with below 0.1mA when power is on.
• Below 0.5 volt the charger will not charge
• Between 0.5V and 2.9V the charger will charge with 80mA down to 20mA.
• Above 2.9V regular charge current is used.
• When charging 2 batteries, the 2A mode will only charge with 1A
• Charger will restart if battery voltage drops below 4.13V.
• Charger will restart charging after power loss, or battery insertion.
• The charger uses 10mA from USB when idle.

A nice CC/CV charge curve with a termination current around 75mA. It start reducing current a bit early, making the charge time longer than necessary.



The second channels looks similar, but the CC/CV cuve is faster this time.



I am not very impressed with the 2A charging, it starts reducing current very early. The battery is charged fine enough, but a real 2A charger could have done it much faster.



The second slot is the same.



To give the charger a change to really show 2A charging I tried a 20700 cell in it, it is much better at handling the larger charge current. Here the charger maintains the 2A until about 3.75V on the cell, then the current starts to drop. It about the same as above and not very impressive 2A charging performance, but it will charge a cell faster than 1A setting.



The 0.5A charging looks fine.



This old a worn down battery is also charged fine, but the charger has problems stopping because it will automatic restart when the voltage drops.



No problems with this cell.



Here I simulate a weak usb charger or a long usb cable and the charger handles it fine.



Two batteries at 1A each also works fine.



M1: 33.1°C, M2: 33.4°C, M3: 42.7°C, M4: 39.2°C, HS1: 51.2°C



HS1: 50.1°C



The charger needs about 0.5 second to start.



There is no problem with changing current while charging.



Charger works fine with a unstable input voltage from a solar panel.



Conclusion

It is a nice little LiIon charger with a simple user interface. The 2A charge current is not that useful, it will only work for one battery (Due to usb current limits) and only for the first part of the charge.
With very old batteries batteries the charger may terminate and restart a couple of times, this is unavoidable for chargers with automatic restart when battery voltage drops.

I will call it a good charger.



Notes

Here is an explanation on how I did the above charge curves: How do I test a charger
Read more about how I test USB power supplies/charger