Want to really know when friction brakes are used ?

Thanks Mr. Fixit! Your data supports what I reported when my Clarity was newer and the brakes had gotten very noisy (maybe there was some sand or something stuck to the brake pad(s)). With this very low tech method, I noticed that the friction brakes are always applied in reverse when you step on the brake pedal (no regen at all) no matter what the speed is. Also, during normal braking, the friction brakes are only applied for the last few feet of a stop, just like you showed in your data. I had also read in a Honda publication that the regen braking is designed exactly in this way to maximize range. Unfortunately, that report seems to have disappeared from the internet. Thus, there is no need to play with the paddles to maximize regen. Just applying the brakes normally will maximize regen automatically.

BTW, one situation when the friction brakes are used exclusively is when the car is fully charged to protect the battery. So if you want to maximize regen and maximize battery longevity, avoid fully charging your battery.

 

A number of owners have experienced the engine starting while using the brakes when the battery is fully charged. This would indicate that the friction brakes are not exclusively being used to slow the car, as excess regen is being “dumped”.

I fully charge every day. Regen is limited when the battery is fully charged, as viewed on the power gauge, but there is still a small amount produced under gentle braking. The fact that the friction brakes are not exclusively used in this situation is one of the gripes that some owners have with the vehicle, because it triggers an otherwise unnecessary starting of the engine.

 

Yes, I've had the engine turn on too when I brake a bit hard, but I can hear the friction brakes as soon as I apply the brakes. If I'm gentle on the brakes, I hear the friction brakes engage immediately and the engine doesn't start. I don't notice much regen on the meter under that circumstance. Having the engine turn on is really annoying so I rarely fully charge my Clarity.

 

The frictions brakes may indeed be immediately applied when applying the brake pedal and the battery is fully charged. The engine coming on would be a solid indication that regenerative braking is also occurring.

It appears that the only time the friction brakes are used exclusively is when the car is brought to a stop from 5mph or less.

 

My experience is quite different. When I leave my garage and get to the end of my street I can turn left to get on the freeway or right to go into the main part of town. The left turn is a slight uphill so leaving home with a full charge doesn't engage HV. The right turn is a very slight down hill with a traffic light about 1/10 mile away. When I have a full charge and see that the light is red I take my foot off the accelerator and coast to the light. Even if I'm going 5 miles an hour when I get to the light and engage the brakes as gently as possible HV kicks on, every single time, no matter how slow I'm going or how softly I brake.

 

We need to see graphical evidence of braking when fully charged. What you say makes sense, but the Clarity PHEV always has more secrets to be revealed. The biggest secret I'm hoping super-sleuths like @MrFixit and @lincomatic can ferret out is what's going on when the engine starts up in response to regen braking when the battery is fully charged. Years ago, this is what I imagined was happening:

 

If you’re saying it makes sense to say that only the friction brakes are used when the battery is fully charged, someone will need to explain how the friction brakes capture and produce regenerative energy, as displayed on the power gauge, I’ve seen it at least 171 times, and then explain why, when the battery is fully charged, the engine starts when sufficient braking force is applied.

If those two occurrences can’t be explained, then we have very strong evidence to indicate that there is some regenerative braking going on, even with a fully charged battery. No charts or graphs needed. Although I suspect one is on the way.

 

I reckon you’ll be waiting for the graphics then.