Is Rex acceleration vibration normal?

[Zpmada]

Hello all,

I have a 2015 Rex that I can feel a slight vibration during acceleration only at low speeds only when the Rex is running and only if the heat / ac are on high. It occurs when the Rex is under a lot of strain but I don’t notice it on the highway.

Is this normal?

I test drove a new i3s and I also felt a slight vibration when the Rex kicked in but it didn’t last as long or resonate as long as in my 2015. I understand the 2018 Rex is a little more powerful?

Dealer says it’s normal behavior and my motor mount bolts were changed about 35,000 miles ago.

Thanks

Thanks

 

[jadnashuanh]

FWIW, there is NO direct mechanical connection between the REx engine and the wheels...the REx drives a generator creating electricity, and that power goes to both the batteries if there's more power than needed for the electric motor, or drives the motor. Changing the load by accelerating could trigger the REx to increase RPMs to try to produce more power, but that is not a direct linkage. It's a small, two cylinder engine, it isn't perfectly balanced, so you might notice a slight amount of vibration from it.

The i3 REx is what is called a serial hybrid. Unlike a parallel hybrid where both the engine and the electrical motor can both drive the wheels, often independently and in conjunction, a serial hybrid always is driven by the electrical motor- the engine is only there to minimize power use from the batteries.

You tend to notice the noise and vibrations from the engine when it comes on because the electric motor is so smooth and quiet with only tire noise and wind noise to help cover it up.

 

[bwilson4web]

. . .
You tend to notice the noise and vibrations from the engine when it comes on because the electric motor is so smooth and quiet with only tire noise and wind noise to help cover it up.

Just drive faster . . . "Sorry officer, my car was making a funny noise that only goes away above 90 mph. That is why I was holding up Atlanta traffic."

Bob Wilson