I did some more limited testing. The battery that doesn’t have the dim green light when off of the charger cannot be used as a battery bank. It does show red when charging and bright green when fully charged and still plugged in. The other one after being removed from the charger or unplugged does show the dim green light that gets even dimmer very quickly as voltage drops. It is not visible anymore at 3.9 volts. When fully charged I was able to use it as a power bank and take out a little under 0.5 amps. Around 3.85 volts that dropped to 0.3 amps. That’s too little to really be useful so I stopped. But that was using the short little lead that they give you plus a USB tester and another cable. There’s a lot of room for losses there. Maybe it does better now that they’re using type C in and out rather than a micro usb.