It has a option maked "Lithium Ion" in the menu for cryin' out loud. Can't they at least address what that means?!
Lithium-Ion batteries are manufacturer-made rechargeable battery packs. I didn't even see a rechargeable battery pack for that GPS unit, so maybe they planned to make one but scrapped the idea. The GPSMAP 76 series does not have the Lithium-Ion option in its menu.
In any case, I'm getting the idea that it is unlikely that we will see lithium battery support in the 60CSx. :-(
On page 91 of the
GPSMAP 60CSx Owner's Manual, there exists this little tidbit:
Battery Life: Up to 18 hours (typical use)*
* Alkaline batteries lose a significant amount of their capacity as the temperature decreases. Use Lithium batteries when operating the GPSMAP 60CSx in below-freezing conditions. Extensive use of screen backlighting, electronic compass, and audible tones significantly reduce battery life.