The "car with the exclamation mark" showed up on our non functioning work iMiev which had been unused for some time. .. The meter was showing about half charge but I put it on charge anyway and went home to get my mulitimeter and came back to find the 12v battery was at about 10.9v so I put it on charge as well. After a few hours it had reached about 12.5 the warning light had gone and I was able to drive the car a short distance. However soon it stopped working and the warning light came on. I will buy a new 12v battery tomorrow but more worrying was that the charge on the main battery did not appear to have increased. When I have installed the new 12v battery I will try to charge the drive battery again. I don't know if the charging system requires the 12v to be in good condition. I hope it is not permanently damaged!