2015 Prius v power cuts off while in motion, anyone?

Strange. Obviously some control and power remained if she could accelerate. I have heard about "limp home" mode when some sensor goes into alarm, like coolant. Let us know what the dealer says.

 

I'd be clueless but 12v batt would be one thing to check..look under hood for rodent damage and in the cabin/engine air filters for mice

 

Also, check the +/- terminals for tightness.

 

what does 'the car was trying to reboot itself' look like to the driver? any dash lights come on?

 

unfortunately, driving straight there won't help. it either stores a code or it doesn't. glad they are replacing the nav anyway, maybe they're tied together. all the best!

 

In a traditional non-hybrid, this is where I'd start. But in a Prius, the 12V battery is unneeded after the car boots up to 'Ready', so my best guess is on a similar loose connection somewhere, but not actually at the battery.

On a previous new car of mine, the problem eventually turned out to be a loose ground strap between engine block and frame. The bolt was put through the cable lug and spun to catch a few threads, but never fully hand-tightened, let alone wrench-tightened. Usually it made good enough contact to start, but sometimes it didn't. Unfortunately, something of this sort could lurk almost anywhere, in innumerable possible locations.

I'm reasonably certain that my problem was linked to an aftermarket accessory (factory-authorized A/C, installed by the selling dealership). The ground strap would have been removed or loosened during installation, and not properly reconnected later.

 

I really wish Toyota would sell a paper service manual and not force us with that on-line manual access.

You had it at the dealer, so one assumes they know what to look for.
Funny the Prius won't leave a historic code.
That in itself could be a lead, as with many cars once a 12 volt battery is disconnected codes erase with no trace.

From above I could echo to check all the body ground straps.
Sometimes there may be a dozen of these and without a manual I have no leads for the OP as where to look to these.

Battery connectors would be suspect on a non-hybrid car.

Last idea would be to lift the Prius and look at the under carriage for a road hazard that may have dmaged the under carriage and wiring harnesses.

Please don't rule out your aftermarket wiring. You did fuse those components and use the correct fuse number (like a 7.5 amp and not a 30) yes? Plus where did you tap the wiring for power? Yep, suspect, I'd recheck that and then totally rule it out as a potential cause.

Good luck.