Regenerative Braking Works Intermittently

I have a 2003 Prius that I have had about 4 years. It has under 80,000 miles on it and I have the Ecrostech Scanner which I have had for about 3 years. For the time I have had the Ecrostech I have noticed times when the regenerative braking was not working when I would depress the brake pedal. I understand the regen does not work from about 7 mph and below but my system often does not work even when it is above that speed. Has anyone had this problem? I have not been able to force it into regen. It seems to have a mind of its own as in perhaps a faulty ecu. Any ideas?

Paul

 

Thanks Bob,
I have seen this regen behavior over about 3 years. I thought perhaps it was standard behavior but have recently thought maybe not. I looked through the threads in Prius Chat and found none that addressed this issue. I live in the mountains of western North Carolina (we have the highest mountain in eastern US, Mt. Mitchell, which I live near) so I have lots of occasions to observe the braking patterns of the regen. Even if my soc is at a low point say 45%, the regen still sometimes does not
kick in when I brake. The intermittent quality seems to be more frequent in the winter but it does happen quite regularly in warmer weather. This does of course effect my mpg though it does not seem to be out of line with others. In winter I get about 37-42 and in summer I get 44-48. Currently I have a reading on the screen of 50.9 in 956 miles. I do get better mileage on the highway than I do in the city driving which might indicate I do not recoup all of my regen when braking at lights in the city. I get even better mileage when I drive from my home near Mt. Mitchell. The 50.9 mpg above has two of those trips in it. I travel from about 2000 feet to about 5000 feet and back down when I travel on the Blue Ridge Parkway to Asheville. When I descend to Asheville my soc gets up to 80% even without braking and so I can get into gliding much of the way, maybe about 25 miles. How is the regen triggered. Is it a microswitch in the brake pedal system? Could that system be faulty?

 

I believe I found the solution to this problem though I have no idea how it fixed it. I decided to get the brake pads and rotors changed on the front of the car. The thinest pad had worn to about 1/8 inch thick compostion material, the thickest was 1/4. Since I have made this change the regenerative braking seems to always be functioning properly now. I have had this problem for about 3 years that I know of. It would appear that even though the pads last a long time in the Prius it is necessary to change them when they get to a certain wear thickness. Toyota perhaps has a spec on this but obviously I was unaware of it. The fact that the pad and rotor change were purely mechanical and that they fixed the problem it begs the question how did the car know the pads were thin since I assume the regen braking is an electronic function?