Hi priuschat family! I got a 2006 Gen II Prius with 70k miles,and I found that when charged to full bars like downhill,engine would turn to very hight rotationl speed for about 10 seconds and then turn off, even the car was stop or slow down, it still happened. I wonder what caused that? maybe the airflow sensor goes wrong or else? And I got Triangle, ABS, & VSC Lights on sometimes,and I used OBDII and Torque and read the code P0A80, but all battry cells voltage seems similar and normal by Torque. maybe the engine in hight rotational speed and overcharge the HV battries and caused the P0A80? anyone know what caused the enging in hight rotational speed when charge to full bars? Thanks!
When the battery is fully charged "actually about 80%" the regeneration in stead of going to the battery is fed to MG1 and used to spin the engine to give a similar effect of the engine braking in a normal car. The strange sensation with this is that if you apply a little accelerator the engine slows down. the reason for this is because you are asking for more speed so engine braking is reduced so reducing the amount of power used to spin the engine. I am sorry to inform you however that PO0A80 points to a fault in the HV battery, probably a bad module. You will need a Mini VCI to read the other part of the code to give more information. John (Britprius)
Thanks for ur reply,but when the enging turn in a hight rotational speed, my car was stop or slow down,not accelerated. So it still confuse me.
If the battery is full "all green bars" this is not considered good for the battery. The engine is turned at speed by MG1 (motor generator) to use some of the battery charge and bring it down to a safe level. This is normal. John (Britprius)
Could it be a failed/failing HV battery? Going down a hill over cooks it, it overcharges and trys hard to get rid of that charge in the usual way. My HV battery is weak and will quickly fill up going down hills even in B mode. If the OP has just bought this car it sounds like the previous owner may have know of the issue. But again, the OP hasn't filled in where they are so we can't say what warranty they are entitled to. Most areas give 100,000 miles/8 years warranty, some 150,000/10 years and some, such as the UK on the early gen3 only gave 60,000/5 years. Saying that, some areas will allow extended warranties beyond those mileages depending on inspections etc, so OPs location is important here too. We're seeing this more and more and I wonder if location should be a compulsory section to complete?
The short answer is that it's normal. It does this by design. The longer answer is that the engine is NOT producing power nor using fuel when this occurs. The Prius's electric motors are spinning the engine, without any fuel injection, purely as a means or burning off some excess charge from the traction battery. Think of it like disconnecting the fuel and just cranking (without starting) the engine in a regular car. All you would achieve is to flatten the battery, right. Well this is basically what the Prius is doing, because there is too much charge in the battery. Of course it's not actually trying to flatten the battery, just shedding some excess charge.
This part is not normal, and would seem to indicate that your traction battery is degraded. This may not be entirely unrelated to your green bar issue. It's a bit of a two way street with this issue, as in a degraded battery will tend to reach full 8 green state of charge more often, but also unfortunately that the frequent full charging of the battery can accelerate it's aging. As the traction battery ages it loses some capacity, and the condition of excess charge occurs more readily (needs lesser sized hills). Also as the battery ages the cells and modules become somewhat imbalanced, and this can lead to faster battery degradation if full 8 green bar state of charge is too often applied, particularly in warm or hot conditions. The battery in my 2005 Prius is also somewhat like this (charges to green more quickly), though fortunately mine has not given any codes yet. I find using "B" mode when descending larger hills to be quite beneficial.
The OP says he is getting P0A80 DTC and I have already informed him this is a battery failure code, but needs to get the other codes that come with it. John (Britprius)
