So, I noticed after the week long heatwave (using Priidash and the Prius display) that during normal driving (under 65mph and slow accel) that my prius is NOT keeping the battery at 60% SOC....It is staying in the low 50's or as low as 39.5%....If I go above 70mph, I see the battery being drained and not recharged at all....I reset the battery (twice) the first time it made no difference but the second time the car turned on and said I had 60% SOC when in reality before the ECU reset I was at 49.5%. I know my battery is good because I have stress tested it many times. Its in great shape. The only thing Ive done differently these past few weeks is I left the car in Park with the AC on 75 auto for about 5hrs on 4 different days....Its a 2004 Prius. Anyone have this issue?
The 12volt battery is fine it was just replaced. I am an electrical engineer so I am pretty familiar with electronics. Car has 200k on it and its in NY
Just wondering what procedure you're using to "stress test" it? And does it involve just an internal resistance test, or is there an amp hour test as well. Maybe the 60% after reset is just an initial guesstimate based on the loaded voltage, and it will get a more accurate figure after it's been driven for some time and does some Coulomb counting.
I would suggest taking a look at your battery cooling fan. At that mileage, it is probably ready for a cleaning. Battery temp should play into the SOC computation, I would expect, as well as the other factors mentioned.
There was a P0420 code the other day which is a bad catalytic converter but the cat has been bad for months. I also noticed according to Priidash that my ice efficiency is only 19 to 20 percent as apposed to the normal 30 to 32...
