Buying preference: 100k+ miles original battery vs new replacement

Assuming a new dealer replaced battery then I'd consider that a plus. I'd caution however that this would be a fairly big assumption to make, unless you have actual proof, by way of receipts from Toyota, that it really was a NEW battery.

If not a new battery then I don't think I'd consider it a positive. To be honest I think I'd prefer to have one that had never been touched.

 

First of all, I would look to see why the battery was replaced so soon. I have 205k on original, have seen up to 250k before needing replacement.

 

You're unlikely to get to the bottom of any systematic reason for this. While it's only a minority of cases, it's clear from looking at the reported failures from users here that some batteries do fail young (100 to 150 kmiles and < 10 years) for no discernible reason.

But yeah, it would be a good idea to check out the health of the battery cooling system for any secondhand Prius with the sort of mileage that the OP is considering.

 

Dealer replaced, factory battery, 2 thumbs up!!