Last week I tested my first a miniture battery pack on my electric bike, consisting of 26 18650 LiIon cells in an 13S2P configuration, giving 48V nominal at 6amp hour, all the cells are in push fit connector blocks, and I managed to do 9 miles, just! This pack gives a maximum continuous current of 30amps for about 10mins, For the OpenPPG kit I will need 10 of these packs in paralelle to get up to the 300amps needed for full power. Before that, I need to make my own BMS, as the ones you get on Ebay just don’t balance the cells very well and I’m going back to basics designing my circuit using www.falstad.com website. This first pack only cost me $130.00, so I’m hoping final cost will be less than $1500 for the whole power pack, the advantage of building your own is that if you get a cell go down you can simply pull it out and pop in a new one, you can garantee the output current and plus its cheaper! Will update with pics when I have some progress.