Hi all,
 I recently installed an adjustable voltage regulator from:
http://www.linkline.com/personal/dbarton/AdjustableVoltage.html

I got the model with the internal adjustable reg., since the alternator
is pretty easily accessible. Now, I have 14.4 V (or whatever I want,
figure I'll turn it down a bit for long drives) at both my batteries,
vs. 13.3 before. This keeps my Optima yellow-top above 13 V when the van
is off. Before, it never got above about 12.3, no matter how far I
drove. No connection to the vendor, but it helped me out and thought it
might help others.

Cheers,
 Jeff K.