# Using Capacitors as Energy storage device - eliminating the phase differ between voltage & current

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#### HRITHU O A

##### New Member
I constantly read that capacitors provide reactive power. So how are they used instead of a battery? I mean in a battery the voltage and current are in the same phase. How is the phase change between the voltage and current in a capacitor eliminated without using an inductor, to use capacitor as a power source?

#### MikeMl

##### Well-Known Member
I constantly read that capacitors provide reactive power. ...
... in an AC circuit!

#### AnalogKid

##### Well-Known Member
There are a few things wrong with your information.
I constantly read that capacitors provide reactive power.
No. A capacitor provides a reactive impedance. How it behaves in a circuit (any circuit) depends entirely on the circuit.
So how are they used instead of a battery?
A battery stores charge in a different manner than does a battery, but charge is charge. In terms of comparing it to a battery of the same physical size, a capacitor holds less charge, can be charged to a high voltage, and has a very steep discharge curve. The good news is that it can be recharged almost instantly.
I mean in a battery the voltage and current are in the same phase.
This is an incorrect expansion of a narrow condition. The phase of the voltage and current are set by whatever the load is, not by the power source. If the load is a simple resistor, the voltage and current are in phase no matter what the source is; battery, capacitor, generator, whatever. If the load is a capacitor, then while it is charging from a DC source the current and voltage are not in phase no matter what the source is.
How is the phase change between the voltage and current in a capacitor eliminated without using an inductor, to use capacitor as a power source?
See above. Phase change in the way you mean it does not exist.

ak

#### HRITHU O A

##### New Member
Thank You guys. Guess I have some more deep reading to do.

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