Cobalt,
The checklists are not a flight manual. The checklists assume that you have read and understood the flight manual. The flight manual has always been perfectly clear - do not take off with a flat battery! The checklists have also always been clear - check the voltage! It is not the job of a checklist to give a detailed description of why every check is necessary - it is up to the pilot to understand his aircraft by reading the flight manual, and understand why each check is necessary.
And it is perfectly obvious when you have a flat battery - the plane won't start so you need the jump-pack. You then have voltage and alternator current clearly displayed on the system page of the MFD so that you can monitor the state of the batteries and how they are charging.
Actually on the Twin Star, due to its design, it's not that easy to see if the tank is empty without looking at the fuel gauges!
There is an external guage supplied with every aircraft - plug it into the purge, slip it onto the purpose made notch on the wing leading edge, and it tells you very precisely how much fuel in each wing. You then reset the fuel flow counters to the amount you have in your tanks. The fuel flow counters then give you a highly accurate readout of what you have left. You also have capacitive guages in the tanks with a display on the MFD to give you a second opinion.