# Why does an increase in capacitor ESR make the capacitor hotter?

According to what I have read online, if a capacitor's ESR increases, the capacitor temperature will also increase and this has me left a little confused.

Consider the simple single resistor circuit below:

If my resistor value was 100 ohms, I would be dissipating 0.25 watts of energy. If I was to replace the 100 ohms resistor with a 200 ohms resistor I would be dissipation 0.125 watts of energy. We can clearly see here that a higher resistance value produces fewer watts and fewer watts equals less heat.

So the question is why is the same principle not occurring in a capacitor when the ESR of the capacitor increases? I would think that more ESR means more resistance, more resistance equals less current, less current equals fewer watts and fewer watts equal less heat. So more capacitor ESR equals a cooler capacitor.

• ESR is modeled in series with the capacitance, not in parallel with the applied voltage. Also, try thinking of a power supply which presents a sawtooth current waveform to the capacitor. – Adam Lawrence Jul 17 '15 at 18:27