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Help me get the right diode - Power Supply Modification

MFDK

Jul 5, 2015
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Greetings everyone!

I'm working with a conversion project here on some server power supplies. (aware of high voltage risks)
A fairly simple mod to turn them from their normal service in (old outdated) servers, to able connecting them in series, deliver and matching up power for RC battery charger equipment.

The basics of the conversion tells to remove and isolate the DC ground internal from the metal case in one supply, while leave DC ground in the other. This with two reasons of making the power supplies work correctly together in series, but keeping as well important safety functions.

Then it is required place two diodes across each output as protection, in cases current should be flowing in wrong direction into one of power supplies. This could be scenarios when the two power supplies doesn't turns on at the very same moment or when only one supply shuts down due to over current protection (OCP) or caused by something else.

Each power supply can deliver about 50A 12V, before the OCP kicks in. Output voltage range about 11,90 to 12,6V.

The attached png illustrate the wiring, but there are absolutely no info to find on the diode.

My question: What do you guys think would be suitable here?
 

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(*steve*)

¡sǝpodᴉʇuɐ ǝɥʇ ɹɐǝɥd
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Jan 21, 2010
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Firstly, I recommend you don't disconnect the protective ground (although I understand that it's common to do this to place these supplies in series)

secondly, I recommend you look up a 100V (or higher) 50A (or higher) diode on digikey. You don't need to heatsink these because they won't be normally conducting. Since they generally fail short circuit, they will fail safely.

Here is a search that should get you started.
 

MFDK

Jul 5, 2015
6
Joined
Jul 5, 2015
Messages
6
Firstly, I recommend you don't disconnect the protective ground (although I understand that it's common to do this to place these supplies in series)

secondly, I recommend you look up a 100V (or higher) 50A (or higher) diode on digikey. You don't need to heatsink these because they won't be normally conducting. Since they generally fail short circuit, they will fail safely.

Here is a search that should get you started.
Okay, thank you very much. I'll see if I can figure this out on digikey.
Type of diode doesn't matter much right? (Schottky, Zener).
 

davenn

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Sep 5, 2009
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Type of diode doesn't matter much right? (Schottky, Zener).

of course it does
a zener has a very specific use, and this isn't it :)


Steve gave you a link to suitable diodes
 
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