Here is a rough electrical diagram of the power bank. It's pretty simple and we have talked about lost of the parts thus far. The one we haven't yet is the switch. I'm not confident that the dc-dc converters will not suck power while not in use, so I added the switch to power them off when not in use. I imagine the charge controller is made to not drawn down the battery it is made to charge.
I think it would be nice to probably put a led on the dc-dc output as well just to make sure it is actually charging. I'll probably add that.