Calling all engineers...stupid question, but here goes:

When you use the electric braking feature, I understand that the TCH uses the magnetic motors basically in reverse as generators, and the energy is dissipated by means of electric current going to the traction battery.

However, if your battery is completely charged, where does all that electric energy go? Does the car dissipate the energy by using the mechanical brakes somehow? Or does it send it to ground?

Thanks.

 

I presume that hybrids work in the same manner as conventional ICE cars. In the case of a conventional ICE, the alternator generates power that is either: A) used immediately, B) charges the battery, or C) is bled off with the regulator/rectifier. Mostly it becomes heat.

 

Once the traction battery is charged to its allowed limit, the mechanical friction brakes take over. This by the way is a major reason that B mode exists - when on a long downhill, the traction battery will max out, and the mechanical brakes take over, which will then start heating, leading ultimately to brake failure (if given enough time). B mode lets the engine take up a good chunk of the load, relieving the stress on the brake pads.

 

I'm not sure how Toyota does it but most systems cut the excitation voltage to the fields in the motor/gernerator which causes less power to be produced by the system. Thus no need to dissipate the extra power because there isn't any.