COLBOR PB74 Battery Base for Wonder Series

Intermittent Output Failure – 2 Units with Same BMS Issue

I am posting this after experiencing identical failures with two separate PB74 battery bases used with the COLBOR W60. Both batteries show 100% charge and accept charging normally from a proper 65W 20V USB-C PD power supply. However, the main DC output to the light stops working completely. In one case, the USB output was also initially inactive, then partially returned after leaving the battery connected to the charger for some time. The main output to the light still remained non-functional. Additional symptoms observed: • Charge level LEDs sometimes remain lit even when the power switch is in the OFF position. • The battery occasionally refuses to start charging, then suddenly “wakes up.” • Output can become completely inactive despite full charge indication. During an on-location shoot with no access to service support, one of the batteries had to be opened as an emergency measure. After temporarily disconnecting and reconnecting the internal battery pack from the control board, it immediately started working again. This strongly suggests a BMS lock or internal control fault rather than a cell failure. Unfortunately, after some time, the same battery required the exact same procedure again. The second unit remains unopened and currently non-functional with identical symptoms. Both batteries are nearly new, were not dropped, modified (except for the emergency intervention described above), or exposed to abnormal conditions. Charging has always been done using a compliant 65W 20V PD charger. Given that two separate units exhibit the same behavior, this may indicate a reliability issue with the internal control board or BMS design. I would be interested to know if other users have experienced similar failures.