RE: Art-tech Pitts special biplane charging help please
.5C delivers 650 ma (650 mah) Per Hr in the constant current stage of charging. You'd be looking at around a 2 hr charge , but the charger should shut off when batt is full.
The charger will do a nice job and I'm a bit hesitant to say "any old" 1300 mah pack , but since the original is 2007 then most any of todays packs will blow it away. Try to look for a 20C or higher , they should be real cheap.