I don't know if it's a bug, or is it intended, but currently, you can stack Void Shield charges, with no hard cap. Every time you activate Void Shield grenade consumable, you receive 4k shield that stays and doesn't goes anywhere, until it's used up... And you can apply it over and over again, stacking 4k shield on top of each other. I've gotten to around 32K shield HP and I got bored doing so. At some point I was just standing there perfectly still with my assassin, tanking everything with Sniper Rifle, because I could.
So I hope it's going to be addressed at some point. Because right now it's a gamebreaking consumable.