DFRobot solar charger output drops to 300mV

Hi, I’m using the DFRobot solar lipo charger board and have an issue. When I supply 5V in and have no battery connected and I get 4.2V output which is correct. The 4.2V goes to the input of the step up converter which accepts minimum 0.5V but it doesnt work. The 4.2V drops to 300 mV. But when I connect the battery, it works! and it works when I disconnect the battery. It works until I remove the power. Do you know why?

Hi Emilija,

It must need to detect the battery to latch closed. They say in the datasheet that they don’t recommend using this without a battery. Perhaps there is some safety built in to try to ensure a battery is used!