Tripmeter kept after 12V reconnect

That is good. How about radio presets, did you have any set?

With our 3rd gen: disconnect the 12 volt, trip meters gone.

 

Maybe this is not an issue with the Prime.

It's a known issue in the 2012-2015 Plug-in Prius. Wouldn't one be able to connect a small battery or trickle charger to the front jump terminal in the engine compartment when doing a battery change to keep all settings? Standard safety precautions, of course, to prevent the positive connector from coming in contact with the ground (chassis).

 

Yes, I do that, when for example: swapping to a new battery. But sometimes you disconnect the battery and want it truly disconnected, to avoid (for example) an off-the-rotor brake caliper possibly squirting out it's piston. Seem like the Prime (and maybe all 4th gens?) have more extensive non-volatile memory.