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[Shop-talk] Which diodes for a battery charger?

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Subject: [Shop-talk] Which diodes for a battery charger?
From: "Karl Vacek" <>
Date: Tue, 26 Feb 2013 21:39:50 -0600
Thread-index: Ac4UnBffJqDy/9kgR3mcHfw0pERjhw==
My old Schumacher battery charger has been dead for years.  Used to be able
to go to the factory for new diodes, fixed inexpensively while I waited, but
they moved away.  I'd like to repair it with better diodes this time.  I'll
also put a muffin fan into the case to help cool the diodes and the huge


The present diodes are little buttons that appear to just be clamped between
a brass contact plate and an indentation in the aluminum flat plate heat
sink.  They're Motorola diodes, MR2502 on one transformer lead (a pair) and
W9312 on the other transformer lead.  The charger is 10 amps continuous, 30
amps fast boost (duty cycle 10 minutes on, 12 minutes off), and 50 amps
motor starting (duty cycle 2 minutes on, 5 minutes off)


I look at diodes and see all sorts of ratings, and don't know what's better
and what's overkill.  May I please have a recommendation as to what rating,
etc.?  A part number to order from XXX company would be even better.


Also - are there positive and negative orientations to the diodes in there
bow?  They're not marked, and if their polarity is related to label
orientation, then one pair is mounted with both oriented the same direction,
while the pair on the other lead are oriented opposite each other.




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