2003 Prius Loss of power

I am always surprised at the willingness of people to say "look, warning lights on my car" and then not read the trouble codes to find out why the lights are on, and on top of that keep driving the car. You really can't count on that going well.

We can make some guesses about what the trouble codes in your car might be likely to be, but the way we could really help would be if you found out what they are and posted them in this thread.

 

Sounds like your car is going into limp mode, which is when it gives up on the main battery and gets all its torque from the internal combustion engine. Driving in this condition is like driving on the little spare tire in the trunk. It's good enough to get the car down the road and in for service, but isn't meant to do more than this.

Bad modules in the traction battery causes the battery to overheat, which will put the car in limp mode and perhaps is what you smell. Since the hybrid system is tied to regenerative breaks, this might be why the break light comes on as well. I think you need a new battery, it sounds like it's past the point of being repaired.

 

Another common possibility is nothing to do with the battery, but more to do with the inverter in the front of the car going into a protective mode because of overheating, sometimes because of a problem with the electric pump that circulates its coolant. It can be ok again after cooling down, for whatever distance it takes to overheat again.

It's because of the variety of possible causes that it is important to know what trouble codes the car is reporting.

 

Note the inverter coolant pump also cools the transaxle motor/generators.

https://atracom.blob.core.windows.net/gears/2009/2009-07/2009-7_22.pdf