Regen breaking and pot holes/rough roads

It is a function of the hybrid drive. The 2010 model years were improved. Then the "fix" made it even less sensitive. So compared to your 08, it will be less sensitive. However, it will still disable regen braking if the wheels are not at equal speeds (slipping, pot holes, bumps, etc).

 

The firmware update after the brake scare with public phobia.

 

Braking. Not breaking.

 

Breaking regen braking, to be honest ;-)

 

And to keep on topic. On 2011 Prius if you hit a hole regen turns off. It's not as sensitive as I was afraid reading forum. Compared to normal cars - it turns off everytime ABS would react. In my car it shuts down only on bigger holes or bump, where both wheels loose contact at the same time.

In winter while braking on snow it allows front wheels to slow down slightly lower that real car speed without kicking off regen.

Another situation when regen is disabled is starting down the hill. When accessing my company garage I have to stop on the top of the hill, and then drive slowly (about 5-6 mph) increasing speed to 12 - 14 mph at the end. If I do it smoothly without fully releasing brake pedal Prius will not start regen. If I release brake pedal for a while after 10 mph and depress it again it will switch to regen.

 

How do you know if you are kicked out of regen?

 

Some people can feel the difference in braking. If you brake lightly (ie 100% regen), you might notice the changeover as it switches to friction brakes at 8 mph, for example. Otherwise, a ScanGauge or something similar will tell you that you're not generating as much power as normal, or that the friction brakes are being used.

 

You can also sense the difference on the braking pedal. While regen or regen+friction a pedal is slightly vibrating (braking force emulator/generator in brake pedal assembly). While kicked out of regen by bump pedal is totaly smooth. You also have to push it a little bit harder (which most of humans do without thinking about).

 

Do you have to be braking pretty hard for this to happen or can it happen if you are braking very lightly?

 

It doesn't completely disable the regen in my 06. It still regen a few horsepower into the HV battery.

I found that if I put it into the B gear, the battery get more regen hp. Yes, the car slows down with the engine braking (pumping air in and out of the cylinders) but I get more regen into the battery. This is another scenario where the B gear can be useful.

For Prius PHV, it is probably not worth starting the ICE with the B gear to get some more regen. It may start the complete ICE warm-up procedure.

 

Friction braking in the Gen 3 Prius is not affected by pot holes any more than other car. The acceleration sensation (surge) while braking on a rough road results from loss of regenerative braking. Because friction braking replaces regenerative braking when pressing moderately hard to hard on the brake pedal, the so called braking surge should be reduced and eventually eliminated, the harder you press the brake pedal.

 

Mine only looses regen braking (surge sensation) when the left front wheel goes over a grate or pothole, doesn't do it on the right hand front wheel.