I have only seen clearance requirements for top and sides, seems to me there should be clearance requirement for the bottom also since the intake fan is in that location. In my location in order to accomplish 100mm for the top it will only leave appx 38mm clearance from the bottom flange of the Multiplus. I did charge my batteries for several hours in the temps of low 90 degees and fans worked fine, but the top was hot to the touch which I understand that is where the exhaust fan is located.