Good day everyone, I have a 2010 Toyota Prius with 135K miles. The Prius has been running lean intermittently this summer. When this issue occurs the following conditions arise: it sounds like the car is running at 6000 RPM in second gear, the dashboard display indicates the Hybrid battery is very low, and the vehicle is slower to accelerate. I am concerned the battery is on the brink of failure. Any feedback or insight would be appreciated. Thanks
Yes. Those symptoms often occur when the HV battery is on it's last legs. But that has NOTHING to do with the gas engine running lean. It is running faster in a futile attempt to charge the battery.
When the battery is low on charge the engine revs up to compensate for loss of battery power, so it's not a fuel mixture issue... The reason your battery is acting this way is because as NiMH batteries age poor conducting crystallization builds up inside the cells and you lose capacity. You fix this by deep cycling, or deep discharge and recharge three times which breaks up the crystallization and restores capacity. Toyota didn't want to do this required service for this battery type so they set the computer to not have any problems with the battery pack even near 50% capacity. But if you want you can restore your pack back to 96% capacity without having to replace it. If you let us know what region in the world you live in we can help you find someone to do this work... Or if you're DIY you can buy your own gear here: FAQ (Frequently Asked Questions) | Hybrid Automotive
