The limits of USB testers for battery capacity measurements

In this video I try to explain why I no longer use USB testers to measure battery capacity. The values can be massively wrong and it gets worse the lower the discharge current. Measuring charge current is generally ok but even there are some issues you need to be aware of. The video where I measure battery capacity without a USB-tester:    • Replacing 9V batteries with rechargeables ?   My review of the UM34C:    • Review and tear-down of the Ruideng UM34C ...   My review of the UNI-T UT658:    • Review and test of the UNI-T UT658 USB Tester