Burning smell going uphill

does it seem like it's inside the cabin, or under the hood?

 

take a look at the inside of the serpantine belt for dry hardness and cracking

 

"Burning smell" is rather generic. Can you describe of what it smells a little better? Electrical? Oil? Something else?

 

The exhaust system is getting hot with the increased load of the hill climb.

Accumulated oil spills, leaks and splashes are probably burning off. Might try a car wash with an undercarriage sprayer.

Does the car have an active oil leak, even a small one?

 

Very common with a tired about to fail hybrid battery.

The hybrid battery supply's the bulk of power to the car so when its tired and cannot provide its rated power the little 90 horsepower go kart engine has to make up for all that missing power. And man is that tough on the engine. Especially if your unaware your missing 80% of your power.

Its especially tough on the engine with hills and a load. Instead of monitoring the battery charge level on the mfd before making a hill run and noticing your in purple bars and oh no this is not good I have no power your just trying to go up the hill at speed like you used to and probably flooring it.

The decline of battery happens so slowly over time you may not even notice it and your just pressing the gas pedal down harder. Only way to see the true battery health story is watch its charge level behavior on the mfd.

Your flogging the engine and the inverter.

After one of those hill runs and you smell the burning pull over and put your hand on the inverter cover. Be careful its going to be really really hot as the inverter coolant is probably close to boiling.

Start reading all the hundreds of posts about a failed hybrid battery cause pretty sure your headed that way.

 

If we're talking about a Gen 2, the little go kart engine is even smaller: 76 hp. But that's still big compared to the maximum 34 hp you can ever get out of the battery (even when the battery is spanking new). 34 hp out of the battery is 125 amps, and while that can happen for quick bursts when you punch it, you're very rarely going to see the battery contributing more than a fifth of that over any longer period.

For example, the time my sister was flogging my Gen 1 up Rockfish Gap at about 80 MPH, the battery was chipping in between 10 and 20 amps most of the way. So, between 2.7 and 5.4 hp. It was definitely necessary, and that little bit made the difference between the car being able to hold her speed or not, but it was nothing like "80% of your power".

The peak "net horsepower" rating for a Gen 2 is 110 hp (76 from the engine, and the maximum momentary 34 you can get from the battery). So the battery's 31% of your power, tops, in a peak sprint like that. In any longer run, it's a good deal less. On that long ascent of Rockfish Gap, it was around 3 to 7 percent of the total.

Over longer periods, the car keeps the average power supplied by the battery right at 0%. If you've just done a burst of hard driving where the contribution was positive, the next thing the car will want to do is run the engine harder than the road requires, and use the excess to pay the battery back.