Don't know if this is related to the earlier problem or not, but now that I know how to check the battery voltage I was noticing it jumping around a lot when I was out driving today. From 11.9 up to 15, and that was while driving at a steady speed of 45mph, often sticking at around 12 for a minute, then back to 14ish for a minute. Is this normal? Or should it being staying in the 14s while driving?