How do you use multi Starboosters separately?

Each starbooster is active for 30 minutes and gives a full bar of energy. If you do not use the energy within the 30 minutes, all of the energy will remain in your energy count. If you are trying to stockpile energy, best to activate a starbooster when your energy is already full. To activate more than one starbooster, you will have to wait until the 30 minutes has expired.

For example:

Original full bar of energy = 110

Activate 1 star booster = 110

30 minutes later, activate another starbooster = 110

30 minutes later, activate another starbooster = 110

At then end of this, you will have 440 energy.

If you have the extended energy bar, the example above will give you 150x4 = 600 energy.