I'm not sure. There must be some losses, but considering that motor controllers these days are fairly small and only need some modest active cooling I'd guess

I'm not sure. There must be some losses, but considering that motor controllers these days are fairly small and only need some modest active cooling I'd guess they're pretty efficient. For example, the motor controller that goes with the Netgain Hyper9 (not exactly the most cutting-edge drive system) can be run without any cooling at all, though it's highly recommended to connect it to water cooling so it doesn't overheat and derate itself. https://www.evwest.com/catalog/product_info.php?products_id=482 https://www.evwest.com/catalog/product_info.php?products_id=...