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Old 03-28-2012, 01:27 AM
Ron Chase Ron Chase is offline
Join Date: Aug 2010
Posts: 57
Originally Posted by BrentA929 View Post

I have yet to try your circuit, but thanks for the update!

I can tell you that I have tried the Douglas Randall K12A and it does NOT work. The breakdown voltage is around 100V. I have yet to try the HFS33 solid state relay. Is the breakdown voltage even listed for those? Also, if we are looking for the capacitor to fill up to 48V and the batteries are sitting at 36V, do we need a breakdown of 12V?

Thanks, Brent

I think the SSR inside the box in JB's video is a Douglas Randall K08A with a FET switch and probably rated for a load voltage around 40-50V. The FET breakdown voltage is not listed on spec. sheets just the load voltage and current carrying capacity. When that voltage is exceeded (from current flow) the FET inside begins to breakdown and dump the cap so that is probably around 48V. I wouldn't worry about trying to dump at 48V why not go for 72V for maximum charging. JB reiterated several posts back that the ideal is to dump at around twice the battery voltage but it seems his machine with that particular SSR dumped at 48V.

If you want to use just a SSR like JB did try a load voltage around 50V rather than the 100V. I prefer to switch the SSR from the low voltage side as JB mentioned.

I'll have two more dump circuits to share soon.

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