Hello, I am new to this and not really sure how this website works but I'm trying to figure it out. I have a 2004 Prius and it has around 119000 miles on it. The car died last month and I have been able to replace it today. The new battery was put in. The car started up and was able to change gears and then the red triangle with the exclamation point came on and I do not know why. Is it because the car sat for a month in this cold weather?
Which battery was replaced, 12V or the big pack? Assuming the former, sitting for one month is more than enough time for the cells in an NiMH pack to get out of balance. Have the error codes read to find out what the actual problem is. If the big pack is just out of balance, rather than having failed in some more dramatic manner, you might be able to have somebody recharge it and it would be good to go for a while longer. When a battery like that, with a large number of serially connected cells, is charged at a rate of 1/20 C or less the more charged cells can withstand being overcharged (as they reach full charge first) which lets the weaker cells "catch up" until all cells are all fully charged. So if the red triangle is because the voltages are too uneven in the big pack, that will fix it.
