Are the electric motor and generator whine louder on cold startup?
 

I notice that I hear a slight whining noise, it's always there with the engine running but it's louder when the vehicle is cold and changes with speed until road noise drowns it out around 30 or 40. Very new to hybrids and general and it's a new sound to me, just want to make sure I'm on top of everything is all, very particular about my vehicles like that.

Re: Are the electric motor and generator whine louder on cold startup?
 

The high pitched whine is normal and comes from the eCVT/transmission. Some people are more sensitive to that pitch/frequency than others so you may hear it while a passenger doesn't.

Re: Are the electric motor and generator whine louder on cold startup?
 

I suspect that you are referring to the PWM switching rate, >15Khz, which very few of us will actually be able to hear.

"..changes with speed.."

While the op seems to be referring moreso to the mechanical gear whine which is noticable to more of us.

Re: Are the electric motor and generator whine louder on cold startup?
 

Pretty sure it is the high frequency motor noise because my father can't hear it and I can just barely. What concerns me is that it pretty much goes away when the vehicle has warmed up, that's my concern, never had electronics quiet up as they warm up, they usually get louder.

Re: Are the electric motor and generator whine louder on cold startup?
 

Most things expand as they warm up, that means tighter coupling between the MG's stator segments and the PM rotor. Those may be the primary source of the >15Khz "noise".

Re: Are the electric motor and generator whine louder on cold startup?
 

Sounds reasonable, anyone have one in a cold climate that can speak to the noise being louder when cold then going away or do I have a problem?

Re: Are the electric motor and generator whine louder on cold startup?
 

How cold was it and was the vehicle sitting 8 or more hours? Where is the noise coming from? Your battery pack will perform a series of charges/discharges (noise) in an attempt to warm itself if it becomes too cold.

Re: Are the electric motor and generator whine louder on cold startup?
 

Not always 8 hours, but it will be when the coolant is below room temperature for sure, kinda sounds like it's coming from the engine compartment, so inverter maybe? It is definitely louder the colder the truck gets on initial start up. I've also been noticing when it's really cold, like under 20 the truck will "seek" 2500 rpm for no reason when it would normally be at 1500 rpm under the same conditions.

Re: Are the electric motor and generator whine louder on cold startup?
 

The higher rpm when really cold is normal. My 2005 does this.

The only noise from the battery in the rear comes from cooling fans that are variable speed and slow down to quiet down as speed slows down.

Normally my motor or generator are not noticably louder when cold.
However, most machinery is louder in general when cold as the lube is thicker and not distributed evenly perhaps after sitting a while.

Also, I believe colder objects (metal, plastic, glass) conduct sound better so normal sounds may be amplified.

In brief, don't worry yourself until you have something to worry about.
:shade: John

Re: Are the electric motor and generator whine louder on cold startup?
 

Yeah, it sounds like it's coming from the front passenger side of the truck, so that would be the inverter making all the noise