Thanks Rodstar. Can't quite fit the 32mm S/P or UWA 14mm in tho.
Mike, If you already have a battery, just peak charge it the nite before use. Another idea I posted, was to buy a DUAL BATTERY ISOLATOR. These, at present, are only avail. in kit form, from Jaycar > part# ka-1782. Priced @ $49.95. A similar unit is prob. avail. at 4wd centres, but may cost a small fortune. These are mounted in the engine bay/car, & both batterys are connected. As you drive to your dark site, the battery is auto. charged.(sorry about the pun)! It may require slight modification to suit the Gel-Cell,(being an "SLA" battery with diff. characteristics), but there are ways.
How deep are your pockets???

L.
Check with your local Auto-electrician.
ps. And you all thought Astronomy was a cheap hobby!