To make a 60A, 220V DC battery charger, how do I calculate output capacitance value to avoid ripple voltage?

I know the C = I*dt/dV formula but is it the same for a capacitive load?


I don't want to trickle charge the battery, so I thought I would use a capacitor in parallel to the load (which is battery itself,) so that I can maintain the voltage output at my desired value using a thyristor controlled bridge. This capacitor must deliver current for charging battery without ripple, so I was wondering if I can use same formula or not.

Does this formula apply only for resistive loads?

  • 1
    \$\begingroup\$ In what way is your battery charger a 'capacitive load'? \$\endgroup\$ Commented Mar 3, 2022 at 6:40
  • \$\begingroup\$ A battery that charges for many minutes with 60A of current, ALWAYS avoids ripple voltage. \$\endgroup\$
    – Whit3rd
    Commented Mar 3, 2022 at 6:49
  • \$\begingroup\$ You need "only" a resistor for limiting peak current ... \$\endgroup\$
    – Antonio51
    Commented Mar 3, 2022 at 6:58
  • \$\begingroup\$ The battery is the massive capacitance load in xxx kilofarads \$\endgroup\$ Commented Mar 3, 2022 at 7:03
  • 1
    \$\begingroup\$ You said you want no ripple, so the capacitance must be infinite. For any practical purpose, the battery is the capacitor. \$\endgroup\$
    – Justme
    Commented Mar 3, 2022 at 9:48

1 Answer 1


There are simple means, but with some issues.
As already stated, no capacitor need.
First try, with a simple resistor (no transformer used). What happens?
Only PULSED sinusoidal current. NB: one can use also a tri-phased transformer (lower ripple).
The resistor limits current. See power in it (avg, RMS).

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One can use also an inductor (case 1 ohm, 10 mH).

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Or a lower resistor (case 0.1 ohm, 10 mH)

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NB: some practical problems to solve.
Power in the resistor (200 W?), current in the inductor (10 mH with 60A?).
Use of some voltage points in the output transformer secondary or auto-transformer.
Use of "electronic transformer". As this one ... To be tested.

enter image description here


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