Just last week we had a series 1 prius that has the battery charge indicator going wild. It would go halfway to full then to yellow with the tortoise appearing. By now our reconditioning process is perfected so we reconditioned it found the battery pretty dead but fixed it sucessfully even changing 6 dead cells.
When we put it back in the car we had the same problem so we drove it around thinking that we had to equalize the cells. This did not work so we had to take the battery out again. We tested the battery again with 100 amp load and found it to be very strong.
The suspicion then fell on the computer. We loaded the battery into another vehicle and lo and behold the same symptoms appeared. Wild jumping of the charge level indicator even though there was good power when the car was driven.
We changed the computer and all problems disappeared. First time that we have ever encountered a computer failure even though it did not bring up a battery fault.
What happened here was the computer software malfunction in the charge input sensors. This triggered a low battery to show the tortoise and reving up the petrol enging to charge and put in more power. It then sense that the battery if at full power immediately and went to half and 3/4 level immediately. Round and round we go as though there was very little charge in the batteries.
Anyone had this problem before?