Pre-Charge Feature FAQ

Modified on Thu, 29 Feb at 6:21 PM

What is a Pre-Charge Feature?

All modern power inverters and motor controllers have a large capacitor bank at their DC input terminals to reduce the ripple current and its associated EMI interference. Input capacitors help to provide smooth power conversion from DC to an AC sine wave and back to DC when charging the battery. When initially connecting a battery to a capacitive input, there is an inrush of current as the input capacitance is charged up to the battery voltage. With large batteries (with a low source resistance) and powerful loads (with large capacitors across the input), the inrush current can easily peak 1000A or more. A pre-charge circuit limits that inrush current, without limiting the operating current.


See attached PDF for more details.


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