I'd be careful reducing battery capacity. The C discharge rating is a multiple of the capacity of the battery. Smaller battery = lower available current.
I would also recommend running the brushless at as high a voltage as it will allow. Going on the black box data from boner when I ran it on 6s and then on 10s later, the current draw difference was enormous. On 6s the motor drew easily around 80a if not more. On 10s the motor was only drawing 10a peak at any time. The 10s was run on a larger motor so that may have had something to do with it but always run brushless at their top rated voltage.
I would also echo the comments regarding the A frame. Aluminium box will just crumple and send the bar into your own machine. A 500mm bar is doable but you would want a much larger motor behind it to get up to speed.
Bookmarks