People are pushing ebikes in ways they never did three years ago, when I was interested.
One of the things that Eric at Luna recenty tossed out is that the BBSHD is 10% more efficient than the BBS02. I don't know, and I don't know if there are hard numbers. My small direct drive motor is less efficient than my large one, especially going up hills. You don't need capacity versus motor wattage, as much as a high enough discharge rate for the size of the pack.
You want to buy a battery that matches the range you want, for sure. How do you figure that? It's not easy when you consider battery capacity can drop, depending on how you charge and discharge the battery. But if you wanted to go 40 miles with a 700 watt hour battery (48v and 15 AH), you could use 80% of that, or 560 watts, for useable capacity. If you divide that by 40 you get 14 wh per mile. The final element in this equation is how fast you go. The watt hours per mile go up, and fast, as speed increases. To go 40 miles you need to get some experience with the motor and battery, use a meter that totals the watt hours for the ride, see if you are in the ballpark. If you have to, slow down.
Nothing in the sales literature makes this very easy. I average about 14 wh with a Mac front 500w motor and a Golden Motor Pie, 1200w. I average around 15 mph and 18 mph open road cruise.
You can always get a bigger battery. Numbers for the effiiciency of various motors are not easy to find. Riding position matters a lot. Bikes like my cruiser, in the member photo, are terrible. Given that people want range and speed, batteries will have to increase in size. EM3ev and Luna sell huge packs. Don't worry about the calibration of the display. You want a separate meter with full information.
A lot of people say a really well designed torque sensing system extends range, but that may be psychological. As the types of ebikes multiply, some of these things can be tested in the marketplace. You can do exactly what you want to do, right now, but you need to be methodical about it.
