The Bosch PowerMore 250 Range Extender discharges in parallel to the main battery. If the PowerMore is connected at the start of the trip, both batteries constantly discharge in parallel and will arrive at 0% battery charge at the same time. If the PowerMore is only connected when the main battery has been partially discharged, the PowerMore will initially be used on its own until the charge levels of both batteries are equal. Then both batteries will again discharge in parallel. As the PowerMore has a different cell structure to the main battery, only 80% of the original power of the PowerMore will be available when it is used on its own. We therefore recommend always using both batteries together.
Updated over 6 months ago