High mileage preventive maintenance items...

You can extend the lifespan of your hybrid battery through a periodic charge and balance, especially if car ever ends up not being used for a significant amount of time. Also with older battery packs you want to clean or replace corroded bus bars, nuts, voltage sensor harness and pins inside ECU. Lastly every 18 months an older battery needs deep cycling, which is a tedious process but does wonders to restore battery capacity back up to 96%.

Maxx Volts and Hybrid Automotive makes products that do this, or you can build one for a hundred dollars in parts: Build Hybrid Battery Maintenance Gear For Under $100 | PriusChat

Here's best place to learn more about the details: FAQ - Hybrid Automotive

 

You're barely broken good drive the car a lot or keep it on a tender for the 12 volt if not and my camper said above every so often you can charge the whole pack cycle it once or twice or if you don't care don't even worry about it just drive it these cars hate sitting

 

Great job taking care of that old Prius! You know one thing I never hear people complain about, our air conditioning! We are a Toyota family and have two from 2008 and, yet, haven't even had to get any A/C recharged. Some good stuff right there, Toyota!

 

Yes if the cars are kept driven rarely do problems arise you're in the Corolla family the Prius is so I wouldn't expect anything but that's as it should be when it isn't that's a problem to me especially with Toyota but since 2010 and beyond the company has become well just like all of them they didn't used to be. The bus bars are going to corrode regardless they're also going to get hot so they tend to turn dark color and look like copper that's been heated but that's easily dealt with just take your kids rock tumbler with some medium grit media throw in the bus bars the nuts whatever other little small parts you have and nuts and bolts you want to clean let that tumble for about 20 minutes retrieve your parts through a screen you'll need to soak them maybe in kerosene or something similar for a few minutes just to remove all grit and traces thereof and all those parts will lay out on a towel and they'll look brand new and there you go yes you could order hardened dipped bus bars they don't seem to do any better than the regular ones to be honest about it when I assemble the battery and all that business I spray the bars the nuts the assembly under the black covers with the stuff lifted up and then I check on that about every 6 or 8 months and I don't have problems with corrosion and North Carolina where it is very humid