If you order premade JST cables make sure the red/black wires are in the correct spots.

[Rolen47]

I spent a few hours trying to figure out why my power boost wasn't charging my battery. When I would plug my battery into the powerboost 1000c both the green and yellow LEDs would stay lit up but my battery was measuring at 0 volts. When I unplugged it my battery measured at over 4 volts. Which means the battery's protection circuit was triggering. Finally I realized that the JST connectors I had ordered had the red/black wires reversed!