JohnJ80,
Bingo! I'll look in to that. Thanks to those that replied. I can't take my main unit as it's just to big and bulky. I'm also looking at a SON Dynamo wheel to see if it has the output to trickle-charge a powerful battery unit like the one JohnJ80 linked to above. If I figure this out and get through this tour, I'll post my findings here for others to ponder if they run a CPAP also.
Please keep posting!