Inverter failure?

It does point to a bad battery. There are a number of options. The best is a new battery; there is a member who makes brand new batteries (I put his link in my signature), or an actual new battery from Toyota.

Before buying stuff, testing is needed. The best way is to use Techstream, a special cable (quite cheap these days), and an old laptop that can run Windows XP (very cheap these days).

I use the iOS version of Torque Pro. While not as good as Techstream, if you can record the screen and if you can watch all the voltages, you can drive in EV mode somewhere quiet and see what happens to the voltages. I think one cell will discharge more quickly, and when the delta reaches 1.1 or 1.2 volts, 'replace hybrid battery' will appear. That same cell will probably also charge up very quickly. The battery ECU will report a full battery if one module is overcharges, and an empty battery if one cell is undercharged - hence the rapid battery charge 'changes'.

I would check this. The best answer is always a new battery. If you are DIY inclined, and if the rest of the battery performs well under load testing, then it could make sense to get a decent replacement cell and switch. It won't last too long, but you can monitor the outcome and voltage deltas etc, with Torquepro, so will have some warning in advance before another repair is needed.

 

I finally got around to replacing the battery. Purchased the NewPriusBattery. So far looks like everything runs good. Thank you for the help everyone.