I can confirm that npcs shields stop recharge, soon as thier Pplant reaches 0%.
They dont have infinite SCB or other utility as well. Only what they dont run out of, its thier ammo pool from weapons, I might be wrong here, as dont recall ever seening npcs that ran out of wep ammo, because they wont last long enough to do it.
They also have to manage thier distro juice, as once its thier PD is destroyed, it will stay at whenever setting they had at moment. Ive seen npcs that was unable boost as often or fire, but note that npcs dont really manage pips like most cmdrs would do, they seem never to fully empty pips from either SYS, ENG and WEP, they always leave 1 pip or half at any of those.