dogman dan wrote:You will need to spend every cent you can on battery. Cheapest small battery than can handle the amps you will be pulling will be RC lipo.
To get the range you want, at 65 kph/ 40 mph, you will need about 60 watt hours per mile. About 2000 watt hours of battery. 27 amp hours of 72v. (20s)
Very hard to carry that much battery. Using more compact round cells, will 72v 27 ah fit the frame?
you don't have to carry as much of course, if you run more like 30 mph for a lot of the trip.
I think his frame will take twice what he needs, I think I saw one here cram 480 cells of 18650's into such a frame.
For >27 Ah a pack made from 200 cells to a 20s10p of samsung 30Q will suffice, at 30 Ah. 2130 Wh. 150 A.
But for heavy use as seems intended maybe consider going for even more in parallell? say 20s14p? 42 Ah. 2983 Wh. 210 A. The less strain you put on your pack the longer the pack life and the better health of each cell.
The price on the Q30 is down to about 3.20 € a piece now. So about 650 for the 20s10p and 900 € for 20s14p. Of course you need welder, wire, and so forth so it adds up. But you get a pack that will last. Also look for deals on Sony VTC 5 as VTC 6 has been out for a while and there have been rumors about VTC 7 already. There was some talk about the Sanyo 20700 B had a price drop to 4 $. I would look into that, if you can find it it will be the best bang for buck. 4250 Ah battery, with 15 A discharge.