I've been looking forward to building a GBZ since I first saw these and I'm getting ready now (parts are slowly arriving).
Today i'm working on the power supply (controls tomorrow).
Power Board/Boost: AliExpress powerboost: https://goo.gl/sOcBP7
I don't have my battery yet (slow postage 3.7v 2500mah Li-Po) nor my screen to connect with Pi so I was using my bench PSU.
After everything I have read on here/wiki/youtube: Recommended battery is a 3.7v LiPo - this power booster shows it charges the battery for 4.2v, is this ok??
Most 3.7v (non AdaFruit) power booster I've seen online here says they charge the battery to 4.2v.
Now thats 1 question - the second is if I'm using a 3.7v battery (surely the output is 3.7v??) I have noticed that this device will not start outputting the 5v until a 4.2v voltage is connected, is this normal for anyone else?
I have two of these and both require a 4.2v to get it outputting 5v.
Sorry if it sounded like ramble

Simple:
1: AliE Power Boost needs 4.2v to start outputting 5v - is this normal and are the 3.7v lipo's we're using going to supply what is needed?
2: Is charging a 3.7v lipo to 4.2v ok? I've seen lipo's go bad (drones) and warnings about over charging.
sorry to ask but It's a slight concern for both

Thanks!!