Electric motor noise

[Carl911]

I was wondering if anyone else has noticed this on there rx450h.

when driving slowly below 40mph and braking lightly I hear a very distinct noise which clearly comes from the electric motors. 

 It sounds like a faint whistle both in light braking and light acceleration.

sometimes it's been loud enough to notice in the cabin with the window closed going down hills slowly with the radio off.

its a little like a rubbing disc but it's not as it only happens when under light braking or acceleration. If I coast the noise goes completely hence  know it's not disc noise.

i don't have any motor noise this audible on the GS450h.

i also notice under harder acceleration I get what I can only describe as air intake noise rather like a turbo car and that often follows by what sounds like a dump valve when I let off the gas. I know these motors are normally asperated so I'm curious what this is.

Carl

[ISJason]

Hi I think what you're describing my RX400 h is the same . It makes those noises when breaking and also when coasting so I don't think there's any need to worry . It's part of the regenerative braking system.

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[Britprius]

When you brake the electric motors are turned to generators turning the vehicle kinetic energy into electricity which is returned to the HV Battery "regeneration". It is the whine from these motor/generators you are hearing. This slows you down without using the normal mechanical brakes, and saves fuel by allowing the energy normally lost to be reused.

When coasting there is a small amount of regeneration to give a mild braking effect that you get from a manual car when you take your foot off the accelerator.

John

[Carl911]

I suspected that it probably was the regenerative braking effect but I have to say that my GS450h is silent.  I know the GS is rear wheel drive and the motors are also on the rear so maybe being further back it's better sound proofed.

i guess having them at the front in the RX makes them more noticeable. 

Carl

[Britprius]

17 minutes ago, Carl911 said:

I suspected that it probably was the regenerative braking effect but I have to say that my GS450h is silent.  I know the GS is rear wheel drive and the motors are also on the rear so maybe being further back it's better sound proofed.

i guess having them at the front in the RX makes them more noticeable. 

Carl

When you brake the electric motors are turned to generators turning the vehicle kinetic energy into electricity which is returned to the HV Battery "regeneration". It is the whine from these motor/generators you are hearing. This slows you down without using the normal mechanical brakes, and saves fuel by allowing the energy normally lost to be reused.

When coasting there is a small amount of regeneration to give a mild braking effect that you get from a manual car when you take your foot off the accelerator.

John

The GS450H has the motors "2" in the gearbox driving the rear wheels. The RX has motors in the gearbox driving the front wheels, and a motor in the differential that drives the rear wheels. The rear wheel drive is electric only in the RX as the differential has no mechanical link to the engine.

John