Basically, I'm trying to build a laptop of sorts. Long story... but I want to be able to have the same type of battery setup. I need between 14 and 24V from a multi-cell lipo pack but I want it to act just like a laptop battery would. Plug in the power adapter and it powers the whole thing plus charges the batteries. Unplug it and it automatically switches to battery power. I've seen a lot of battery management boards for charging multi-cell lipo packs (in series) but they all seem to be for charging the battery without any external load. So how do I even do that? Preferably is there some sort of pre-existing board I can use for this?