How to test a charger?

It is a good charger and with the compact size it can easily be used as a travel charger, especially if you are hauling other usb equipment. Charge time is good with one or two cells and acceptable with 3 or 4 cells, but you have to manually add two hours if you want to be sure the batteries are completely filled. As usual I am not impressed with NiMH based power banks (4 AA battery is about the same power as one 18650 battery), but with this compact charger it is a nice extra, even if the usefulness is a bit limited.