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Old 06-24-2009, 11:34 AM   #1804 (permalink)
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Originally Posted by MPaulHolmes View Post
I don't know why they increase the ripple current so much.
Not sure if you were really looking for an answer, but this is what i've gleaned from discussions on the EVtech and EVDL.

I think it has to do with temperature - too much heat generation causes the temperature of the caps to rise which decreases their expected life. lower ESR means lower heat generated, so you can pull more amps from it.

Apparently one of the reasons using many smaller caps have a higher combined ripple current rating than one large cap is because the larger surface area. More surface area means the caps are easier to cool. cooler operation means more ripple current capability.

Like you, I've decided to add a couple of low ESR caps (film, i think) to my charger design. i'm still in the process of laying everything out on a PCB, but i hope to have results soon!
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