In X3 each shield requires a certain amount of energy to recharge at the maximum speed. A 25MJ shield requires 250kW to recharge in 1min, 51sec (the maximum speed). If a ship has three shields, it will require 750kW (3x 250kW) to recharge the shields at the maximum speed. If a ship has only half the energy (375kW), then the shields will recharge at half the speed (so 3mins, 42secs). If the ship has more reactor energy than required, it will not make the shields any quicker than the maximum speed. All shields share energy equally.

Name Size Usage Recharge time Cargo
1 MJ Shield 1 MJ Shield 1MJ 33 kW 31 secs 1 (S)
5 MJ Shield 5 MJ Shield 5MJ 83 kW 1 mins, 3 secs 3 (S)
25 MJ Shield 25 MJ Shield 25MJ 250 kW 1 mins, 51 secs 10 (S)
125 MJ Shield 125 MJ Shield 125MJ 833 kW 2 mins, 47 secs 25 (L)
1 GJ Shield 1 GJ Shield 1,000MJ 277 kW 66 mins, 51 secs 77 (XL)
10 GJ Shield 10 GJ Shield 10,000MJ 2,777 kW 66 mins, 41 secs 222 (XL)