A big difference is that the shield booster uses capacitor energy to give you bigger boosts to your shields. The recharger does not use capacitor and thus the amount it helps is smaller.
Which one to use - depends on the ship and what you will be doing. Both of the modules have situations where they work better than the other one.
| Shield Recharger | Shield Booster |
|---|---|
| Passive module - Always works. (You don’t have to switch it on) | Active module - You have to manually switch it on. |
| Makes the shield recharge faster (reduces the total recharge time) | Immediately adds a number of ‘points’ to your shield each cycle while it is active. |
| Does not use capacitor. | Uses lots of your ship’s capacitor. |
| Works even if you have 0 capacitor energy left | Stops working if you don’t have enough capacitor energy |
| Can’t overheat. | Can overheat. (which will gradually cause damage to the module) |
| 1 size. | Small, Medium, Large, X-Large, Capital sizes. |
| Uses less CPU and powergid | Uses more CPU and powergrid. |
| Used along with other passive modules, for example shield extenders, shield flux coil, shield power relays, etc. | Generally used along with boost amplifiers, and modules for improving your capacitor amount/recharge. |