downhill whine

[rockcandymountain]

So, I travel this one particular route that has a downhill section. Normally the electric motor helps maintain a speed of around 40-45 mph. While doing this, the electric motors aren't too noisy. However, today going down that hill, there was an abnormally higher sounding whine, sort of like how a standard tranny would 'wind up' if you dropped it into 2nd gear. I looked down at the gauge that shows if I'm using electricity or fuel, and the gauge was pegged at 100% electricity, which I would expect. Just curious as to the higher pitched wound out electric motor sound.

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[wax87]

could it be the AC motor?

 

[Sykotyk]

It's the engine braking. You've maxed your battery and that's the only way to slow down without frying the battery.

 

[The Real Maverick]

So, I travel this one particular route that has a downhill section. Normally the electric motor helps maintain a speed of around 40-45 mph. While doing this, the electric motors aren't too noisy. However, today going down that hill, there was an abnormally higher sounding whine, sort of like how a standard tranny would 'wind up' if you dropped it into 2nd gear. I looked down at the gauge that shows if I'm using electricity or fuel, and the gauge was pegged at 100% electricity, which I would expect. Just curious as to the higher pitched wound out electric motor sound.

It's a bit deceptive and the "regen" needle in the green lies sometimes.

It has been proven/demonstrated that the needle in the green means electrical regeneration OR engine compression braking OR a combination of both.

It can be proven/demonstrated if you have accessory PID scanners plugged into the truck while driving.

The sound(s) you heard WAS the engine spinning up to slow you but no fuel was being burned. The same net effect as downshifting.

 

[AutobahnSHO]

What they said. Engine braking. The truck doesn't put fuel into the motor. It's still compressing air to get ready to explode, but no explosion then the air escapes out the tailpipe.

The auto-downhill braking is one of my wife's favorite features on the hybrid- we live where it's really hilly and it's so nice to not have to ride the brakes down the hills like 90% of folks do. She was getting 16mpg driving our minivan to work, gets 37 in the hybrid.

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