Your 30 minutes flight time plus taxi time should be enough to recharge what you have used during the start. So, I personally dont see any problem with that. The Caravan was built with battery starts in mind.
Like Brian said, when you flick the start switch, have a look at what voltage you see indicated. A good battery will give you around 18 Volts initially (PT6 small series and 40Ah lead acid battery in warm climate), gradually increasing as Ng builds up.
If you get at least 16% Ng before introducing fuel, the electrical side is fine.
In the operation I am in at the moment, we only do battery starts and the company gives us a new battery every 18 months. They found it is cheaper than mess with ageing batteries.