I am looking forward to construct sort of an electric scooter that, hopefully, I could later manufacture and sell in small series.
Right now I am thinking about the kind of batteries should I use, Li Ion or LiFePO4.
If I heard it right, Li Ion ones are more-or-less unsafe and can easily explode if overcharged, also the pack cannot be simply soldered together, as there should be a separate wire going out from every battery to the charger, so that it could control and balance all that bats. in the pack, right? Also, while not sure that its true, I was told that Li Ions cannot be soldered in Parallel, only in series, therefore you cannot increase the Amps, is that so?
As for the price, I found them at about $2.9 + shipping for 3.7v , 2200mAh. That way a pack of about 36v, 8800mAh would need about 40 units and would cost roughly 120$.
The price for the LiFePO4, I believe, could be somewhere similar, with a higher safety. Do you know whether they need a separate controller for each unit? Can they be wired in parallel, etc. ?