The most misunderstood aspect of the Toyota hybrid synergy drive system

Well, I found my cruise control applying about 13 kW of regen, as I went down a particular hill in Indiana.

I'm pretty sure if I had canceled cruise and pressed the brake pedal, more than 13 kW of regen would have happened, up to whatever the power management control ECU was reporting for the charge control value at that time. The gen 3 repair manual gives a normal value for that as "−33 kW or more" (where they're saying "more" because it's a negative number, so, for example, −27 is 'more" than −33). The ECU can adjust the charge control value to "more" (i.e., gentler regen) if it finds the battery to be hot or tired.

 

Here is another documented example of how automatic engine braking in shifter position D works:

Yesterday, by chance, I happened to drive down a hill with my 2007 Gen 2 Prius in D mode, and when the battery reached max SOC, engine braking automatically kicked in. I did not shift to B mode.

Here is what my realtime display setup looks like:

Cd6eef63-1800-465d-b2b0-c2b9b5b6ce5f-1_all_32813 by Fred_H posted Jul 6, 2024 at 3:43 PM

Data logging was also enabled with ten second log intervals. Here is a graph of a portion of the logged data, from shortly before regenerative braking, through the transition to engine braking, to shortly after engine braking:

1000015032 by Fred_H posted Jul 6, 2024 at 3:43 PM

 

great documentation fred, thanks!