John Popelish said:
Whether the power supply can provide more amperes is not just
dependent on the diodes. But to address the diode question,
paralleling with a similar type will allow a bit higher current
without destroying the diodes, but not twice as much. The diodes will
not share the current exactly and each will heat the ambient air near
he other, so each will get hotter for its share of the current than if
it were operating at that current without its partner near by.
Even alone, a 1 amp diode is not normally expected to deliver 1 amp
average, except under the most ideal of conditions (leads heat sunk to
25 C a short distance from the body, for example).
John...
This fellow's question brings to mind a similar concept I had over on an
automotive group - Alternators are fairly tough little beasties - Most
of the guts of them are all but indestructible short of physical damage.
But a very common failure mode for them is for the diode trios to barf
if/when they're asked to try to charge a mostly-dead battery.
I had the thought not too long ago that paralleling multiple diodes per
"trio position" should give at least some added "anti-fry" protection in
terms of how dead a battery the alternator can charge without burning
itself (or more specifically, its diode trios) up.
Since it's such a common failure mode, and cheap to repair (compared to
"buy a new/reman alternator and replace as a unit") the benefit would
potentially be huge to the person doing such a mod to their alternator.
Now, it sounds like you're saying that rather than improving the
situation, such a setup would likely be an actively BAD thing?
Is the "extra heating" issue still a significant problem in a forced-air
environment such as what I'd have in my particularly alternator? (diode
trios in it are heat-sinked, and are the first thing that the air, being
actively pulled in through the back of the alternator by its built-in
fan, encounters)
It would seem to me, at least at first glance, that "stacking" multiple
diode trios (let's say to three diodes per phase and polarity, for a
total of 18 discrete diodes (versus the standard 6 -- two, one for each
polarity, on each of three phases)) in this beast would be beneficial,
if only in terms of "Well, that one over there cooked, but I'm still
doing fine, and so is the one next to me" style backup - should one
fail, the remaining two for that phase pick up the slack. (Of course,
with such an arrangement, if there's an overload big enough to blow one
of the diodes, I think it unlikely that the other two would survive as
they were forced to pick up even more of the load that managed to burn
out one of the three already...)
Which doesn't even start to address the whole "Since three of them are
sharing the load (however unevenly they might be portioning it out
amongst themselves) there should be little or no reason for one to fail
in the first place" concept...
Gimme a sanity-check on this idea, would ya, John?