Without Charge mode... so like when the hybrid battery fills, diverting the extra brake charge voltage to the e-battery. Is this possible?
Yes and no. The batteries will charge only to some level. If you go to one of the best-est places in the world, the MT Washington Presidential range, and near if your near a high point and haeding downhill, and the hybrid battery starts at 100% charge, if you have the ac/heater off, no lights, no wipers, etc, then there's very little power draw for the rest of the car. Iirc, at some point the ICE (engine) will come on, to provide additional braking power. However, if your near a high point, and you have your headlights on, the AC/heater blasting full, wipers going all the time, radio blasting, and so on, then it's possible that the battery level will still show "100%", and the power produced from the brakes, or "B" mode, will provide charging back to the battery/charge system. However, most/all of the braking power back to the battery/charge system will be going to the other electrical loads (headlights (via the 12v battery), heat, etc). The hybrid/traction battery also charges the 12volt battery. The 12volt battery powers headlights, wipers, radio the fan for the AC/heat, the fan for the traction battery cooling, and so on. The traction battery directly powers the AC compressor. So, things can get confusing and muddled. Plus, people often use generic/high-level terms/concepts. So, yes, braking does provide electrical power for the headlights, but it does so through a few indirect paths. I hope the above helps. Good Luck!
I think the Toyota guy on YouTube says the ICE spins for engine breaking but does not actually run when the battery is full and you're applying the breaks while going down hill (for example). The ”EV" indicator might turn off, and the crankshaft turns, but no gas or spark.
