The shield is effectively an extension of hp and has to be brought to 0 for the character to suffer any actual hp damage. Like actual hp, it benefits from your armor. Obsolete with Energy shield MK2
It takes 4.167 seconds to recharge from 0 to 50 hp. Multiple Shields recharge simultaneously.
The maximum shield recharge rate is ([number of energy shield MK2] * 50 / 4.167) units per second, if enough power is provided by batteries or portable reactor. But only is applied when all shields except the last one is depleted.