Those have diesel engines. You don't know what you're talking about. The electric drive is to make power transmission easier, and yes, to allow for regenerative breaking.

It allows regenerative braking in principle, I don't know if any mining truck actually has one. Imagine the size and weight of a battery to power a 200T truck (total weight up to 385 metric tons) for any significant time. These trucks use induction brakes, which do not give back any energy, for the same reason they use electric motors instead of a gearbox - a lone friction brake for such a heavy machine would be too heavy and wear out too quickly (they do have auxiliary friction breaks, though).

Yeah, you're right. I had two different Komatsu PR things open and one was talking about regenerative braking and the other was for these electric drive trucks. Doesn't look like they have any sort of battery. Just alternators to generate electricity from the diesel engines.

Thanks for the comment. I took the previous poster's comment at face value (seemed like common sense). My internal db has been updated.

The comment is wrong. Those trucks have diesel engines. It's even on the page they posted. The electric drive is for power transmission/traction control.