- Better to think of batteries in term of watt-hour or Wh
- Two 36V 3.4Ah battery packs in series is 72V 3.4Ah not 6.8Ah but both are 122 Wh of energy
- Look up YT videos on how to properly make a battery pack. I would recommend buying one first, setup the bike, ride it for a while and after you learn more about batteries then make a pack. At this moment, I don't think you should make your own pack
- Use this calculator to determine your minimal voltage and power motor requirements. Note, this is minimal and you should get the next power level to be safe.
http://www.electricbikesimulator.com/calculator.php?language=en#
- To go a top speed of 35 mph, you will need 1500W. To be safe you should plan for a 2000W motor.
- Using same parameters above, for a 20 mile range you will need 830 Wh battery pack but you should plan for 1000 Wh+
- Depending on the battery grade, you might have a negative amp draw to capacity curve. Meaning if you draw high amps, you capacity goes down say 25-35% of rated. This is why you should try to get a higher voltage system or very good batteries
- I do not like duo 1000W motors. It is unnecessarily complicated especially with two controllers you will have so many wires your brain will explode. Get a single rear hub or mid drive motor based on the calculator determinations (remember to go next level up)