My Zippy 3s 5Ah softpack is 146x50, height won't be an issue. I'm hoping the curved sides of the batt tray mean that a softpack a few mm longer can be squeezed in, it will only need 1.5mm on each side, but I'm worried about the width. May need to find a way to mod the battery door to get an extra 3mm. DAMN! 3mm too long and 3mm too wide. Sounds like it should be supplied with a dremel