Gen 3 Insight Forum banner

Engine Braking / Noise when HV Battery is Full

10K views 20 replies 9 participants last post by  Mobilcams 
#1 ·
I've been using the regen braking paddles very actively for the past 2 months (since I bought my Insight). I use it when I am approaching to a full stop (traffic light, intersection) regardless if it's a downhill or not. And I will say it's helping with the mpg, not a lot but quiet enough to make you smile to see the difference!

However, I realized, if I am over certain speed like 50mph, and then try to apply the regen braking paddles, I hear a roaring sound from the engine, and it kinda makes me wonder why. If this paddles are only acting as brakes, why the engine struggles and makes the noise? Almost same noise as if you're trying to floor it after a full stop, anyone else experiencing this? Or am I not supposed to use paddles above certain speed?
 
#2 ·
I realized, if I am over certain speed like 50mph, and then try to apply the regen braking paddles, I hear a roaring sound from the engine, and it kinda makes me wonder why. If this paddles are only acting as brakes, why the engine struggles and makes the noise? Almost same noise as if you're trying to floor it after a full stop, anyone else experiencing this? Or am I not supposed to use paddles above certain speed?
I've heard a sound like you described, though for me it was when accelerating while in a high-regen setting. I think the sound relates to the "engine-to-generator" transition happening as regen is added. To help the transition, I try to apply or release regen gradually at higher speeds.

The electric motor becomes a generator by running backwards as regen is applied. The level of regen (and paddle use) controls the degree of the motor being "generator" rather than engine. More regen means more "back-torque" applied in the reverse direction of the drive shaft, creating a net feeling of braking. It's really a complex set of transitions that are more technical than 'acting like brakes.'

It gets kind of technical, but the following are some video descriptions I've found, plus a simpler link/attachment with description of regen:
[0:21 - 2:23] Regen Braking1 - youtube.com/watch?v=BhOEoXfxHMc
[1:00 - 3:40] Induction Motor - youtube.com/watch?v=EWZkFX48vu0
[1:52 - 4:00] Regen Braking2 - youtube.com/watch?v=0b2i5ufN7k0
[see #4 - snapshot attached] autobytel.com/hybrid-cars/car-buying-guides/weird-noises-your-hybrid-makes-and-why-126954/
 

Attachments

#3 · (Edited)
I realized, if I am over certain speed like 50mph, and then try to apply the regen braking paddles, I hear a roaring sound from the engine, and it kinda makes me wonder why. If this paddles are only acting as brakes, why the engine struggles and makes the noise? Almost same noise as if you're trying to floor it after a full stop, anyone else experiencing this? Or am I not supposed to use paddles above certain speed?
The engine roar on deceleration occurs when the rate of charge is exceeded and the ICE needs to kick in (not using gas - just the clutch lock-up) to take the load off. This occurs during a very fast slowdown from high speed or when the battery is full and there's no place left to store the energy. At that point, engine braking kicks in. It's totally normal, but was scary the first time I had it happen! The engine isn't really struggling - it's helping you bleed off speed!
 
#4 ·
I bought a 2007 Acura TSX used in 2010. The first time I was driving down a steep hill (on the middle and east of America you would call it a mountain) in the rain, it suddenly downshifted and the car started to skid. It happened more than once that winter and it was pretty scary. I was told there was some computerized system in it that decided that lower gear would be better. I guess that's similar to our regen braking kicking in.
 
#5 ·
So I just did a trip from dc to Pittsburgh lastnight and the engine noise was let's say...less favorable. I had the car in sport mode mostly but that was because I enjoyed the immediate regen down hills. The strange thing was once the battery was full and I was going down a long hill without any throttle the engine freaking roared like I was engine braking down the hill the entire way. I thought that was so strange. I'm hoping on the way back Normal mode won't do that. I also like sport mode because it maintains a higher soc on the battery than normal or econ.

I'm wondering if some heavy duty sound dampening material on the engine firewall would reduce some of the low frequency noise...
 
#7 ·
So I just did a trip from dc to Pittsburgh lastnight and the engine noise was let's say...less favorable. I had the car in sport mode mostly but that was because I enjoyed the immediate regen down hills. The strange thing was once the battery was full and I was going down a long hill without any throttle the engine freaking roared like I was engine braking down the hill the entire way. I thought that was so strange. I'm hoping on the way back Normal mode won't do that. I also like sport mode because it maintains a higher soc on the battery than normal or econ.

I'm wondering if some heavy duty sound dampening material on the engine firewall would reduce some of the low frequency noise...
It was!! Hit the gas "feather foot will keep you in EV" and make a free mph run at the next hill !! :smile_big:
 
#6 ·
If your battery gets topped off, the Insight needs to put the regen energy somewhere, and that's through engine braking. It will get noticeably worse of the battery is topped off and you use the paddles to jack up regen - there's no place for it to go.
 
#9 ·
I was driving on the freeway and there was a downhill grade. I used my left paddle shift to slow down and regen. I noticed the battery level was pretty high and heard a high rpm from the engine, meaning it is also engine braking the vehicle.

My question is: Does the single speed transmission that engages at high speeds have variable ratios?

I read from many places saying that it is a single ratio direct connection. But then engine braking wouldn’t be possible.

Any thoughts? Thanks!
 
#10 ·
The engine braking is from the main traction motor energy being dumped into the generator motor that will then use the engine as friction to electrically brake the traction motor. It's basically turning the engine into a resistor electrically. There's not transmission involved. The lockup clutch (direct engine clutch is only one ratio) essentially an overdrive gear - if you were to try using that to slow down the car it would never work.
 
#12 ·
What's interesting about it is in the morning when the engine and electrical system is not warmed up or ready, I have heard the engine braking when coming up to a stop sign at relatively low speeds. Pretty interesting way to bleed off excess power. I wonder how big of a resistor they would have to make to mimic the resistance the engine/battery offers.
 
#13 ·
Hopefully I'm not oversimplifying this too much, but if the battery is fully charged why would you try to force regen? It seems to me that you would just use the brake pedal to slow the car. Unless of course you are in a mountainous area where it would heat the brakes excessively, then I could see using engine braking to slow the car. Just my 2 cents worth.
 
#14 ·
Welcome to the forum. There are a couple tricky parts that we can't manage once the HV battery is full:
1) the car's hybrid/charging algorithms - even after full, the charging algorithms still sends power to the HV battery.
2) initial travel of the brake pedal is regenerative - friction braking only kicks in at speeds of 10-15 mph and/or during emergency braking; even if you "think" you're using the brakes when the HV battery is full, you're actually still triggering regenerative energy to be sent to the HV battery
 
#19 ·
Here's a section from the 2019 Insight Press Release:

Electric Servo Brake System
Employing a microprocessor-controlled combination of electronic regenerative braking and hydraulic braking, Insight provides a smooth and linear braking response in all driving conditions, while also improving fuel efficiency.
The electric servo braking system is fully hydraulic from the master cylinder all the way to the 4-wheel disc brakes, just like a traditional braking system. The key difference is that the braking function is electronically controlled rather than a purely mechanical activation, allowing regenerative braking from the electric drive motor to slow the vehicle, rather than the hydraulic friction brakes under many circumstances. Besides its efficiency payoffs, the system offers excellent feel and feedback through the brake pedal.
When the driver applies the brake pedal, a signal is sent to the vehicle's Electronic Control Unit (ECU), which determines the appropriate amount of braking force to assign to regenerative braking through the electric drive motor and to the hydraulic friction braking system. In many light-to-moderate braking situations, friction braking is not needed until the vehicle speed drops below 5 mph, as the vehicle slows to a final stop. When the ECU determines that friction braking is needed, the dual hydraulic master cylinder pumps brake fluid through the system. Midway between the master cylinder and the calipers is a separate motorized electronic actuator. This actuator receives an electronic signal, generated in the master cylinder module that precisely defines how the driver has applied the brakes – soft or hard, slow or fast. The actuator then directly apportions hydraulic pressure to the brake calipers at each wheel. To maximize the Insight's accident-avoidance capabilities, the system delivers an extra-strong braking response when the driver increases the pedal force.
The 2019 Insight is equipped with 11.1-inch diameter ventilated front brake rotors (0.9-inch rotor thickness) clamped by single-piston brake calipers. The rear disc brakes incorporate 10.2-inch diameter solid rotors (0.4-inch rotor thickness) paired with single-piston brake calipers. The low-friction design of the brake calipers reduces energy losses when the brakes are not in use, directly improving fuel efficiency.
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top