Breaking question.

Sounds alot like you're not actually speeding up. You may be losing braking power due to the ABS doing its job. It is slightly removing pressure from the brakes to keep the wheels from sliding.

 

this is a feature that comes at no extra charge, enjoy!

 

I am going to discuss braking, if you really meant breaking, I am at a loss.

When you stop the car normally you use regenerative braking, which uses Motor Generator 2 (connected to just the front tires) to make electricity and store it in the HV Battery.

When you have an uneven surface, this can apply stresses to the drivetrain and also may let the rear of the car get loose, so when you hit bumps while braking, the ECUs switch to Friction braking (Disc Brakes) which uses all 4 wheels to slow the car but has a slightly different 'feel' than Regen.

The short gap and the different feel can cause you to think you are accelerating. This is a kinetic illusion, like an optical illusion can fool the eye.
When the Gen3 first came out, the gap between Regenerative and Friction brakes was longer, if you have an early 2010, make sure the recall was performed.

 

This is old news. The car is not really speeding up. There IS a decrease in braking deceleration when the car switches from regenerative braking to mechanical braking. Your brain interprets this as acceleration. There was a recall that changed the car's programming to minimize this. I suggest you check with the dealer if the recall was done.

 

This issue has received much discussion in various threads on this cite. Simply stated, light braking activates the energy regeneration system, with more aggressive braking activating the ABS system. If you start braking and then drive over a bumpy surface, both of these systems are momentarily inactivated, giving the feeling of acceleration. In reality, friction braking is unaffected, although continued stopping at the same rate will require additional braking pressure.

 

(if it seems we are ganging up on you, I bet all of us read the question and composed answers thinking ours would be the only answer. At least we don't disagree, it would be more confusing if we gave different stories)

 

Listen to JimboP..... He has nailed it on the head.
Just depress the Brake Pedal harder. Find some crappy rough surface street that is not well traveled. Drive up and down the street at varying speeds, then Brake, get the feel for it, how to manage it, and then how to master it, lastly how to ignore it.!

 

+1

We're a helpful group

 

The Runaway Prius returns! :car:

 

So this isn't a breaking question about braking, but instead an old question about braking.



For the OP: ABS brakes do this. They allow some wheel rotation to maintain directional control. Given the two-wheel nature of regenerative braking, the Prius is more likely to go into ABS over bumps than an ordinary car. The resultant short reduction in braking effort feels like acceleration, but it isn't. It is actually a reduction of acceleration, or what we engineers call "jerk" - you feel the car jerk forward.

Tom