Current batteries maintain themselves warm with a heat pump to avoid that degradation. The drop is mainly the energy of activating that pump. If you have a Tesl

Current batteries maintain themselves warm with a heat pump to avoid that degradation. The drop is mainly the energy of activating that pump. If you have a Tesla, that’s the fridge-like noise you hear when you warm it up. Diesel engines typically run (inefficiently) to warm themselves up and be efficient, but that is a larger energy cost, mainly because that process captures a fraction of the heat from the combustion.