Muliple indicators lit up simultaneously while idling.

Pull the codes with the Mini VCI and then post back with the codes.

Without the codes you are guessing.

Best of luck to you and "Welcome to Prius Chat"!

 

You can visually check the inverter pump. You can see a slight flow on the surface of the inverter reservoir, looking down the neck with good light. You should also be able to hear a slight hum from the pump, which is behind the left headlight. Do this in IG-ON mode, engine off.

11.5 is very low for the Prius battery. Keep an eye on that and start shopping for a new one. I got a pretty good deal at the local Toyota dealer, about $200 before tax.

Also, check the engine coolant level in the COLD radiator. You'll have to remove the splash shield for access, six tricky little fasteners. Check the water pump for leaks by looking for pink residue. How does the cabin heat work, though now is probably not a good time to check.

 

I had a battery malfunction a couple of months ago. THE CAR WOULDN'T TURN OFF! I was leaving a parking lot at 10 pm and I noticed the whole dashboard was dark after I turned the car on. I restarted the car and it still didn't work. When I got home, the lights were still off, but the car wouldn't turn off either! I tried for about 3 hours. I was low on gas too. I decided to disconnect the battery while the car was running (which was probably unsafe, but I had no other choice). The car turned off, and I decided I didn't want this happening again, so I got a new battery. All is well now.

Sorry, but I have no idea what your problem is. I say get a new battery. I don't think the car tells you the battery is almost dead; it freaks you out with a bunch of warning lights.

 

Your problem was probably the combination meter (CM), a well-documented problem with the Gen II Prius. There was a warranty extension offered about five years ago, good for nine years after in-service date. If you're too late for that, there are DIY options available for just over $100.

The problem is intermittent, and usually occurs on cold days. If/when it happens again, maybe next winter, the car can be driven to a safe place, then turned off by holding the start button for a full three seconds or so.

 

Yes. Connect to the hybrid battery ECU and that will give you block voltages (pairs of modules). P0A80 is telling you there's too much difference. It may take a few tries to achieve that connection, depending on your PC.

 

The DTC should give you freeze frame data on what happened when the code was thrown. I haven't had to do this, but I hear you click on the snowflake icon next to the DTC log to get there.

Battery voltages are dynamic. What you see at idle may be within threshold, but will be different at rapid charge, discharge, resting or different temps.

If this is a low-mileage vehicle in otherwise good mechanical condition, you like the car, and want it to be very reliable for many years, definitely invest in a new battery. It may good for another nine or ten years. If you like to tinker and can accept some risk in transportation reliability, go the module replacement route. Lots of threads on that--some get lucky, some get headaches.