Hymotion and Regen -

The Hymotion battery does recharge the stock battery if needed and as long as there is enough charge in the Hymotion battery. But I don't recall seeing the regen for this process. I'll keep my eye on it to see if I see the same thing.

 

Yes, Regen is occuring while braking even when the Hymotion system is in operation. As a matter of fact, it is something of a concern to some of the Toyota Tech Experts (who shall remain anonymous) with whom I have spoken. The concern is possible overcharging of the original Prius Hybrid battery. So far, I have no other information on this particular subject.

 

Regen with a Hymotion system operates the same way it does in a regular Prius, with all of the same limits in place. For all intents and purposes, a Hymotion Prius thinks that it IS a regular Prius. So, there is absolutely no reason to be worried about overcharging. (If you know something that I don't about possible causes of overcharging, please let me know.)

The only difference is that, when the Prius traction battery goes down to a certain level, the Hymotion system starts sneaking little batches of energy into it (when it's not looking).

So, a Hymotion Prius will do slightly LESS regen. That's because the Hymotion system will not let the traction battery go below a certain level. By design, that level is slightly higher than the level at which the ICE will kick on.