thats alot of stuff to run into a V3!
what is the V3 outputting to?
I think the original poster means V3 > VX-Pocket > Powerbook.
Power for V3 - several good options:
6v SLA - your V3 is probably already calibrated to run off one of these. Check out the Archival Info forum for how to build your own easily.
RC batt - lighter weight and smaller in size than SLAs, a bit more expensive, requires re-calibrating the low-batt light / auto-shutoff on your V3 if you want to continue to use those features.
LiON batt - there's a 9v LiON WalMart DVD battery some people have used on various gear. Again, a bit more expensive than SLA and requires re-calibrating the low-batt light / auto-shutoff on your V3 if you want to continue to use those features.
FWIW, Grace Design hosts instructions for recalibrating the V3 low-batt / auto-shutoff on their website.