Everyone, thanks for your replies! I'll try to answer a few questions: no
fuse is present in my converter, mistake 1; no blocking is present to
isolate the feedback point from the batteries, mistake 2.

The converter died (the spark I mentioned in the OP) when I attached the
positive output of the converter to the positive terminal of the
battery. The solar panel positive was not hooked up at this time to the
converter. The spark could have been because of the output caps charging,
but that shouldn't have killed the converter...

Tomorrow I'm going to take the convter apart and try to determine what is
wrong. Thanks for the comments. I've never built a high current boost
converter before, so this has been interesting and a bit frustrating...

Matthew
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist