Not flown one myself but one of our group members went to pick up a Twinstar for the local flying school but found it had a flat battery when he arrived so decided not to take it. He then found out about this incident so good job!
Another thing he mentioned is that when the battery goes flat the gear extends by default so now not only do you no engines but you have massive drag as well and if over water your point of no return is suddenly several miles behind you....
Julian.