hot temps

I would guess that in this hot weather you have been using the AC. The combination of the hot weather and running the AC, especially on short trips, have a big impact on mpg.

If you are running the AC this is probably the humming that you are hearing. The AC compressor is variable speed and controlled by the Inverter module. The humming that you hear is the switching frequencies of the power components in the Inverter and compressor motor.

To check the AC, turn it off and see if the humming goes away.

 

Yes, regular highway driving with AC should not impact mpg that much. Also, if the HV battery is showing low while highway driving this is definitely an issue.

My HV battery will show low during in town driving while stopping at stop lights, etc. when the ICE shuts off with the AC on. But once I get moving again the battery charges right back up.

Let us know what the dealer says.

 

The dealer will say "that is normal operation".

 

Yep on all of the above. Open up the the windows to hear the compressor turn on/off when you turn the AC on/off.

On the 2nd gen, the AC compressor can get quite loud if you're outside.

 

no way does my mileage drop from 52 to 40 with the a/c on. especially on the highway. i get 50-55 all day long on reasonably flat highways at 65 mph.

 

How hot and what is the length of your trip. I do get big drops here. If its hot and the battery is low at the start it takes extra energy to recharge the battery. If I'm only going a few miles on the highway I'll get in the 20s. Then the next trip it will pop up. Uphill12 mile trip to the lake saturday in triple digits gave me 38mpg. I don't know if there is something different on the guys like bisco that can get 50 in the heat, but I imagine its the route, but hey my car may have something wrong too I average around 42 last summer.

I doubt the dealer will find anything even if its hot, but good luck. Did you have the car last summer? Did it act differently?

 

If your going down the highway and your battery is getting low i would let someone ride with you and record that. if your going 55mph the hv battery should stay almost full.

 

+1 to austingreen. Try doing short trips in 110 degrees. Even with careful driving habits, my avg mpg (city surface streets) goes from 50 to 42. Granted, if I can get some freeway miles in, it will help bring it up again.

I've also noticed the SOC get down to 2 or 3 bars on a regular basis in this heat. The compressor really sucks the power.

 

Your mileage does seem out of line then. On longer trips when I'm not in a traffic jam, the battery does charge up and mpg does rise.

I do think there is likely something wrong with your car. I am not that good with remote diagnosis though. I would try running in eco to see if its the ac drain, but there may be a problem with one of the batteries or sensors. Electrical problems are tough to figure out. Hopefully someone more versed can help.

 

If the hum is coming from the *back* seat then it may be the traction battery cooling fan, and the traction battery system may be unhappy.

 

Try force charging the HV in two modes. 1. Without AC 2. With AC. In both cases you should reach the 2/3 charge point. W/O the AC on, you should reach the green bars, not necessarily total green. If the car can do that it's OK. If not there may be a problem. use the 72-78 F temp range.

 

What temperature is your A/C set to?

 

Went on a trip, mostly highway with A/C on. Got 60 mpg!

I do notice around town with short trips I average around 40 though. It's been humid and around 90 -- have major humming. Scared me at first but realized it happens just when A/C is cranking, mainly when I first turn it on and the car is hot (park outside).

 

I was going to observe the same fact, especially if there is anything on the back seat that is blocking the intake duct.

 

Hopefully there is NEVER anything blocking that duct! The owners manual points this out.