Does the IMA motor/generator recharge the battery pack only during braking?
It depends on the battery pack’s state of charge. When the charge is bellow 2/3 full charge, the IMA system will siphon off some of your engine’s power to recharge the battery pack at about 20% of its maximum recharging rate while I’m cruising at a steady speed. However, if you accelerate while this parasitic recharging is taking place, the recharging stops–even if you’re not accelerating enough to kick in the IMA boost.
