Hi Paul,
Not sure that I remember any distortion when mine went - it was a long time ago! As far as I was concerned, I suddenly had no sound without any warning and I immediately looked to my lead, my amp, my pedals... everything but the bass. At the time, I was playing in a wedding band and you just have to keep them dancing, so it was a case of the rest of the band playing a nice, piano-based smooch number while I changed my battery.
Lesson learned, but Mica's response gives me a lot more confidence now, however, I will continue to check the charge regularly!
Have a great New Year!
Rob