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If you had to come to a stop on a flat from about 1/2 mile away, going about 55mph, how would you use the HCH2 to maximize the energy recouped along the stretch?

I was under the impression that light use of the brake pedal induced some amount of friction braking, but does anyone here have a sense of how much pressure is too much to add, or where the proper cutoff is?

For e.g. I generally immediately coast from the 1/2 mile point, then shortly after that pull mostly or fully off the gas to achieve 3-4bars regen. Then as the stop is coming up to 1/4 mile or so, light brake to get the 6-8 bars regen (at e.g. 40mph) and try my best to keep that even brake pressure up to the stop.

Does anyone else have alternate strategies for the HCH that they think favors regen over friction?

Dogarm--

I think you're right. I've found, depending on terrain, that I can light up anywhere from 5 to 6 of the regen bars without feeling what I take to be the friction brakes really grabbing on. This is somewhat confirmed by some experimentation with with the S mode of the CVT. S mode is roughly equivalent to B mode in a Prius in that it simulates engine braking. If you drop the CVT into S you'll see about 6 bars or so of regen, which I think is the maximum all-IMA braking level.

My conclusion from this is that 6 bars is about the limit for all-regen braking. Beyond that I believe you're throwing some energy away to heat. This shrinks with speed, of course. What I do (and what it sounds like you do) is maintain pedal pressure constant as the initial 6 bars as speed slows. I suspect this maximizes the regen over the duration of the braking.

MSantos probably knows way more, though. He always does. He'll probably tell me I'm wrong, too... --RN

Hmm... sometimes I switch from D to S (with foot off gas) and this seems to increase regen/slow the vehicle. Is this more efficient than using even light brake pressure to get regen?

SB--

You are correct that you can use S to brake the vehicle. I don't believe the S mode enhances the efficiency of regen, however. MSantos described S mode in another thread, and I believe he said he only uses it in cold temps to induce regen when the car normally wouldn't invoke regen on braking. I suspect if it yielded other benefits in efficiency it'd be more widely used.

Again, I'm not the expert, but I play one sometimes on CleanMPG. --RN

Well, I don't know if I can be of much help here folks.

The main reason why is because much of the regenerative profile for the HCH-II is actually determined by the software and to make things even more elusive, it takes quite a few variables as inputs.
The same goes for the assist profiles as well. Right now I am a little frustrated by some of the changes Honda performed on my 06 as a result of a series of recent updates. And since rollbacks are not possible, I am condemned to wait for the next release. What I am trying to say is that it is likely for our experiences to vary, depending on what is "pushed" to us in terms of future updates. :(

Anyhow, according to the literature, the hydraulic brakes will not kick in unless the regen graph is almost maxed out - that is as simple as I can put it. However, there's also the threshold deceleration rate which is a factor in engaging the hydraulic brakes much earlier - such in the case of a panic stop where EBD is also likely to intervene.

I believe the light use of the brake pedal is the most optimal regen opportunity especially when regen braking is available.

In the summer, I am not a big fan of bleeding speed by switching to S, mainly because there's a definite wear factor to consider. So far, the greatest enemy of the CVT transmission continues to be heat, and I am not too sure that the hydraulic cooling that Honda implemented on the HCH-II is up to that kind of use. Of course, more frequent H-ATF fluid changes may help mitigate that negative factor, but still I am not convinced the design allows for frequent use of the technique.

However, during the winter months I am less concerned about wear due to "down-shifting" because (1) the temps are low and (2) the regular regen braking is not always available and keeping a good SoC is very helpful.


Cheers;

MSantos

If you've got pressure sensors on the brake lines, you might
be able to hang a voltmeter off one to be able to read a
quick-n-dirty equivalent of my pressure monitor (http://techno-fandom.org/~hobbit/cars/bp/) thingie, and
at least see where your rise occurs. Probably want the rear
wheels since they're likely to get it first.
.
_H*

That's a good idea hobbit. As far as I can tell these pressure sensors wires are aggregated in the connector 25P that could be tapped for the readings. Nice.

On the other hand, the HCH-II has a Servo Unit Electronic Control (SUEC) which dumps these pressure values + a dozen other equally relevant values into the F-CAN bus as well. An average CAN reader should pick those up quite easily along with the other EBD stuff...
Gee, I gotta get me a compact CAN reader one of these days. :)

Cheers;

MSantos

Thanks for the nice feedback! Bottom line - light braking, and trust the feel of the car. Oh, and beware the firmware update :)

In our informal experiments, we would have to agree with Msantos.....
"In the summer, I am not a big fan of bleeding speed by switching to S, mainly because there's a definite wear factor to consider."

Well, I don't know if I can be of much help here folks.

The main reason why is because much of the regenerative profile for the HCH-II is actually determined by the software and to make things even more elusive, it takes quite a few variables as inputs.
The same goes for the assist profiles as well. Right now I am a little frustrated by some of the changes Honda performed on my 06 as a result of a series of recent updates. And since rollbacks are not possible, I am condemned to wait for the next release. What I am trying to say is that it is likely for our experiences to vary, depending on what is "pushed" to us in terms of future updates. :(

Anyhow, according to the literature, the hydraulic brakes will not kick in unless the regen graph is almost maxed out - that is as simple as I can put it. However, there's also the threshold deceleration rate which is a factor in engaging the hydraulic brakes much earlier - such in the case of a panic stop where EBD is also likely to intervene.

I believe the light use of the brake pedal is the most optimal regen opportunity especially when regen braking is available.

In the summer, I am not a big fan of bleeding speed by switching to S, mainly because there's a definite wear factor to consider. So far, the greatest enemy of the CVT transmission continues to be heat, and I am not too sure that the hydraulic cooling that Honda implemented on the HCH-II is up to that kind of use. Of course, more frequent H-ATF fluid changes may help mitigate that negative factor, but still I am not convinced the design allows for frequent use of the technique.

However, during the winter months I am less concerned about wear due to "down-shifting" because (1) the temps are low and (2) the regular regen braking is not always available and keeping a good SoC is very helpful.


Cheers;

MSantos