On Sat, 21 Jan 2012 05:27:16 -0800, "William Sommerwerck"
wrote:

No one mentioned putting a string of silicon diodes in series to lower
the voltage. Unlike a resistor, the voltage drop would be reasonable
fixed. But, no fancy parts, capacitors, etc are required. Sort of
crude, but why wouldn't it work? 7 diodes would drop approx 4.2 volts
bringing 13ish down to 9ish. Or, maybe 8 diodes to be safe. 13.8 down
to 9. Just wondering why no one mentioned the possibility. Heat
would have to be handled, but no worse than a three terminal regulator
and the heat would be spread across all 8 diodes.

Excellent idea. 1N400x rectifiers should work.

Exactly! I have a bunch of 1N4003's in my junk box that I used for
any project needing a general purpose diode that can handle some
power.