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Forum Index : Electronics : current drop Diode

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irishron40
Senior Member

Joined: 22/09/2014
Location: Ireland
Posts: 251
Posted: 01:47pm 08 Aug 2016
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Hello,

I am using a 160W 12V Solar Panel which I think can produce about max 8 amp hour.

I just wonder what procentage voltage and current drop I would have when I let the current flow thru a 10A Diode.

Thank you

ron
 
powerednut

Senior Member

Joined: 09/12/2009
Location: Australia
Posts: 221
Posted: 05:14pm 08 Aug 2016
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Take a look at Ohms law, and the datasheet for your diode and see if you can get there. You can find a good reference here: http://www.ohmslawcalculator.com/ohms-law-wheel

But you haven't given us enough information to answer that for you. We need to know what diode.

for starters, 160W at 12V = 13.3A (I=P/V), so your diode is not going to survive. It probably will for a while, until you get over 120W power, and then it will die.

Voltage drop (look for Vf in the datasheets) across the diode will depend on which diode your using, and how many amps. For a standard silicon rectifier diode, that'll be somewhere in the ballpark of 0.6V, up to about 1.1V. Something like a SBR10U150 will be 0.8V drop at 10A, and around 0.7V at 5A. BTW, at those sorts of power you'll be producing around 8 Watts in heat from your diode - so pick something in a case style you can put a heat sink on.

A schottky diode will typically have a lower forward voltage drop. For example, a MBR1040 schottky rectifier diode will be more like 0.5-0.6V, which will be 5 Watts worth of heat @ 10A (still need a heat sink).

btw, neither diode should be used in your application - they both have a max current of 10A. I've just picked them because they are cheap and ballpark fit what you've told us. A MBRF3040CT would be a better choice than either, as it has a higher forward current rating (30Amp) and around the 0.5-0.6V forward voltage drop. Its also cheaper, currently at AUS$0.25 at element14 for low quantities (i.e 1).

hope that helps.

 
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