On Sat, 14 Sep 2013 13:46:14 -0400, "Jim Wilkins"
wrote:

"Ed Huntress" wrote in message
news
On Sat, 14 Sep 2013 11:53:48 -0400, "Jim Wilkins"
wrote:

"Larry Jaques" wrote in message
...
On Fri, 13 Sep 2013 10:01:37 -0400, "Jim Wilkins"
wrote:

The Schottkys are D1 and D2, in series between the panel and
battery
on the positive side. When one failed short the charger kept
working
normally. Q6 connects the negative side.

Why the 2nd diode on a DC-only circuit? Reverse polarity
protection?

Likely inadeqate current rating. They are 3A diodes in a 4A circuit.
The problem is that if one heats up its forward voltage will drop
and
it will hog all the current, assuming they were initially matched
and
shared evenly (Ha!). I may have caused that by adding two more solar
panels which pushed the current over 3A.

If they're in series, Jim, they both pass the same current. The
current "hogging" you describe can occur in parallel circuits.

And if they're in series, they each carry the *full* current. They
divide the voltage.

--
Ed Huntress

You didn't look at the schematic I referenced, did you?

Nope, I was going from what I could make out from your words.

I realize you know electronics, but it looked like you mispoke, from
the way your description read.

The two diodes
are in parallel with each other and hopefully share current. The PAIR
is in series between the panel and the battery, so when one shorted
the charger continued to work.
jsw

Yeah, I see it.

--
Ed Huntress