Solar Power Manager V1(9/12/18V) - Battery Charging Indicator

Heya - I'm using a larger 5000 mAh LiPo battery hooked up to the main board. I'm charging it up with an old 2A iPad charging wall wart. It has taken ~8hrs for the red charging LED to turn off, but the green 'done' LED never turns on. There are other use cases where it does turn on, but not when the battery is done charging. Does anyone know why this might be happening? Does it have to do with the size of the battery or the protection circuitry? Thanks!