Newbie with 2002 Prius Gen 1 NHW11 91,300 Miles

My wife and I took possession of subject brand new Prius November 2001 and have had a great experience. Heart City Toyota, Elkhart, Indiana has performed all service/maintenance and they have been fantastic. At 60K miles, I had them perform a complete service including changing all plugs, filters, and fluids including, as suggested by this forum, pulling off the transaxle pan for inspection of the magnet which I personally inspected and found to be completely clean/free of metallic fragments (Yeah!).

On first set of tires, I did have premature tire wear at 25K. As suggested by Toyota, replaced with OEM, had full alignment, and got 35K miles. Decided on my own to try Yokohama Avid Touring which are on it now at 90K and probably good for another 20K.

On the 12V accessory battery, I've had a little dumb luck. First one was good for ~6 years but got weak. Decided to replace with a Mazda Miata AGM Battery and installed with mod on my own which worked great. It lasted ~3 years and only failed after we didn't drive the Prius for 2 weeks with a rear door accidentally left ajar and wouldn't take a charge. In haste, replaced with a standard lead acid Autocraft 12V but strongly advise against using standard lead acid as it only lasted 2 years, became weak the last 6 months, and killed my mileage. Just replaced that 12V with a Staab Mazda Miata AGM and hoping for better luck on this one.

While replacing the 12V today, noticed inverter coolant reservoir well below the "Low" mark and have no idea how long it has been this low. I'm certain no leaks as I keep garaged and no evidence of leaks of any kind ever on floor. Fortunately, confirmed I'm still getting coolant flow in reservoir with key in ignition position--will top off with Toyota long life (red) coolant and hope bad air flushing from the 60,000 mile fluid change. If that is the case, will be disappointed both I and Heart City missed that low coolant level in the inverter last 30K miles of oil changes. Other than that, in below freezing weather this winter, on cold outdoor start occasionally noticed a mid-pitch hum that quickly disappeared in area of passenger side engine compartment--uncertain what that might have been but wondered if engine water pump.

Certainly can't complain about my experience so far. However, at this age, beginning to wonder about the traction battery. Hopefully won't be an issue because I'm guessing replacement would cost as much as the car is worth making difficult to justify.

As a newbie on the forum, thought I'd share my experience and solicit any insights or suggestions from members on keeping my 2002 Prius running smooth for another few years.

Best Regards,
James