I seem to recall reading that at least one other person has had the following problem: Toward the end of my usual 20-mile one-way commute, with about half a charge showing, I started to lose power, and eventually got the "batsult" message. After a recharge at work, the same thing happened toward the end of my ride home. I put another mile or so on to see what would happen, and it eventually dropped to no charge showing, and zero estimate miles left.
This has happened a second time now, with several uneventful commutes between incidents. I have to say my confidence is a bit shaken. Has this happened to others? Does anyone have any theories as to what the problem could be?