My experience parallels ElanC's. I live at the top of a 4 mile 7% grade (about 1200 ft elevation change). When I drive up to my home, it usually quickly depletes the battery down to 4 bars, and I lose the assist. In fact, it sometimes goes into charge mode while climbing the hill. Going down the hill, the regen charges the battery all the way up to 8 bars. Other than that, the charge usually is in the top half.