It was not my concern that I had to drop a shortcut for the priority selector. I only use a few of theese shortcuts. I just wanted to point out, that your mod is practically "invisible" in vanilla game setting.
Having two generators at the same priority normally distributes the production between them according to their respective max power. I would argue, that this should be the same with generators / batteries. As Batteries are used quite in numbers (at least in my games), they tend to have a far higher peak power than the regular generator. Therefore, although they would run together with the generator, they should do the main part of the work.
The problem (you probably got in mind) could be, that the generator would constantly try to recharge the battery. I think this should not be the case, as battteries do not do this to each other, even on different charge levels. I think I read about this issue in a FFF aeveral months (years?) ago.
Regarding the "work / shutoff" setting: I just noticed, that the "shutoff" setting is meant for deinstallation of the mod, e.g. re-setting al changed generators to their vanilla status. Right?