Review on KEDSUM Quiet Rechargeable Battery-Operated Aquarium Air Pump With Dual Outlets - Perfect For Fish Tank, Outdoor Fishing, Transport, And Emergencies by David Cronin

After just a few days the unit would not take a charge. After some troubleshooting with various cables, and reviewing comments with similar issues, it seemed the charging port was the likely failure. I decided to power the unit directly, removing the charging port, cut the power cord, drilled a hole to run the cable through, and soldered the 5VDC power wires direct to the wires on the opposite side of the charging port. It now consistently charges the battery, every time its plugged in. The battery lasts a long time once charged, (running but not plugged in) running on green light for more than 8 hours before turning yellow and indicating a charge is needed. And after 24 hours it was still running and light was red, so in my opinion the battery is OK. So if you have some time on your hands, (I'm retired) and are handy with a soldering iron and volt meter, then this is the product for you.