battery isolation for portable power.
Pretty much i have salvaged 8 18650 size cells that i would like to run in parallel to make a portable battery. In order to boost capacity, i would like to buy new cells and make another pack that is parallel also. I want them parallel so its a nominal 3.7v system that i can boost to 5v for USB devices
I know its bad to run old and new batteries in parallel do to various reasons such as self discharge. My idea is have 2 usb ports for one pack and 2 ports for the other pack and have an input/output protection PCB per pack. Now to keep this more portable i only want to use 1 charger and this is what confuses me. I can charge each pack separately, but that would require me to swap packs on the charger, and i would rather not have to worry about doing that.
Long story short, how can i charge 2 battery packs at the same time but keep them isolated from each other? Diodes maybe? Also with how the protection circuits work having the charge leads connected to the output leads and the batteries on there own leads, when the charger is outputting over one amps, will it hurt any device plugged into it or will it regulate the current down to one amp with no harm done? Link to usb charger and protection circuit.