Hybrid Battery at 230K miles

Warning lights and gas mileage would confirm that there's a problem but in your case they don't indicate there's a problem. So looking at more obvious issues, such as a bad tank of gas, dirty air filter / intake system on the engine... Or maybe you're a hoarder and the car is full of 800 hundreds pounds of clutter? But again at 48mpg it being a battery or engine inefficiency problem seems unlikely. Looking forward to what others have to say on this one...

 

What did the battery bar do when you were going up the hill?

 

Is there anything preventing you from pushing the gas pedal all the way to the floor? You mentioned you're always light on the gas pedal.... Maybe experiment with how your car responds to flooring the pedal as often as possible? People might think you're a crazy driver for doing that but your MPG data and power in the hills might give a better sense of what's going on if you tried that.

 

Most likely your HV battery is getting weak, but if no warning lights have come on the modules are still reasonably well balanced. When you say you go to the mountains, how far away from your home is that? The first time you get a warning to check the hybrid system you will likely still be able to drive it in "limp home" mode for perhaps a few hundred miles, but it will become even more sluggish than it is already. With that many miles, the entire car is probably near the end of its life. I would continue to drive it until it dies or becomes so unresponsive you can no longer put up with it. Our 2007 currently has 267K and that's the path we have chosen, although that car's replacement is currently sitting in the driveway next to it.

 

I have had a similar thing happen when climbing a long steep hill. Basically the battery bar went slowly to 1purple bar then the engine sped up. I didn’t slow down though. It actually makes sense as the engine and wheels are never physically connected at any time. The engine was just producing as much electricity as it could and the drive motor was using it all. As soon as I hit the top of the hill the battery stared charging again.

 

Sounds like it's a good candidate for a full battery reconditioning or a proactive battery replacement before it fails. As dependable as the Gen II is, I would hesitate to replace the car if there is nothing else wrong with it and it has been well maintained. A new HV battery is going to last at least another 8-10 years so that part of the car will no longer be a worry. A Prolong reconditioning system is a lot less money but the jury is still out on how long it can extend an old battery's life and requires the car to be "out of service" for a week, twice a year.

 

I am not sure a gen 3 is a good option if your gen 2 is in excellent condition otherwise and does not burn oil like the gen 3s are prone to do. Concerns include the cost of a gen 3, its future battery issues (which are an unknown) and the 2008’s low resale value with a worn battery. Bottom line, if you like the car as a commuter, then fixing might make sense.

Quick kbb says a 2008 with 230k has a resale with the old battery (without ripping someone) of maybe $1500-2500. With a good battery maybe $3500-5000 or more especially if it had a new battery. Your old battery lasted well over 200k miles and 10 years, so a new or rebuilt at 230k would add value. Right now you can get a rebuilt with 2 year warranty for $995 installed or a new installed for $2295. Link below.

Regardless, I would be hesitant to take any 230k car on a long trip when excellent rental deals can be found for things like vacations.

I would consider getting the Dr Prius app and a $28 obd2 bluetooth reader to test and read codes. They have a load test and it will read hybrid codes including individual modules inside the battery. Testing requires a one time $12.99 charge. See link.

Pricing | Hometown Hybrids

https://www.amazon.com/gp/product/B06XTP3HDG/ref=oh_aui_detailpage_o02_s00?ie=UTF8&psc=1

Dr. Prius / Dr. Hybrid by Big Wheel Tech Inc