SYC:

From what I read on the specs on the Pro Peak 2500VP, it is mainly for NiCd and NiMH batteries, and has a specific cut off voltage for the typical RC battery (4.8 to 9.6). It does not show an output for 12vdc batteries. You will need something to output 13.6 vdc for the lead acid battery. Same for a gel-cell. If you can go to a car parts store, pick up a cheap car battery charger that plugs into your mains system (wall plug).

Best of luck with that project.

DS.