Hi,
I use a car starter battery for powering my LXD55.
I bought a small fused transformer to plug into that, the kind that you can buy for connecting a CD player up to the cigarette lighter socket in a car (which the battery also has).
This works fine for many many hours even in freezing conditions.
I have only once blown the fuse when I got the alignment way off, confused the scope as to where it was and it ran itself into the mount, straining the motors and then blowing the fuse!
www.weasner.com/etx/techtips/battery-ps.html
does seem to indicate that 12v would be ok though with NiCads.
Cheers,
~Al
  