Recently bought a 2008 RX 400H AWD with 185K miles on it. I have no idea whether the hybrid battery has ever been replaced. It's my understanding that the vehicle is sometimes supposed to drive powered by the hybrid battery.
When driving downwards on a slope for several minutes, the battery can go from just 2 bars, to around 75%-90%. That seems absurd to me, as if the battery's charge capacity has been entirely diminished so it only stores a fraction of what it originally could. The battery also gets depleted in a similar manner. This does not surprise me, but since I'm averaging 22 mpg, I'm not inclined to get a replacement battery.
Oddly enough, driving around until the battery is charged up and then parking it overnight results in diminished charged by morning. For example 80% down to 20%.
I am terrified about the hybrid battery possibly failing and shutting down the vehicle while I'm driving at speed on the highway. Are these just standard symptoms when the car is at this age or should I be looking into a replacement?
On that note, I'm curious whether the hybrid battery in the newer models work with my old model?