Chall Acustica said:
I see, that does make sense. What kind of batteries could get about 200 km of range with lower weight? Currently this scooter has a 4.1L tank and a mileage of 56 kmpl (not particularly good). If the hybrid system will be less efficient I would be happy going full electric. If it helps, the current weight of the bike is 95 kg, and I weigh 45 kg. I am expecting to hold up to 80 kg extra though, in case I carry a passenger or two, or cargo, but certainly not going at full speed with extra weight.
If you use that simulator to guesstimate power usage (peak / continuous watts) and wh/km consumption under your various riding conditions, at least for average and worst case conditions (including with and without the extra passenger/cargo weight), you can then determine how many Wh your battery will have to have to give you that 200km of range under the worst of those conditions that you will still require that range, *and* the worst-case wattage the batteries must be able to provide.
Knowing the Wh tells you the "size" of the battery, and knowing the W tells you how capable the cells in it must be.
You'll want to add some percentage (I'd go with 25%+) of Wh to account for degradation due to aging (and if you have colder weather, allow for less responsiveness from that), and for detours or headwinds, etc., that decrease your range so you still have the full 200km available even under those conditions.
So if your calculations came up with say, 4kwh, you'd want 5kwh or more.
Some example calculations based on made up data, but you can substitute your own data once you have it:
Let's say your W (watts) worst case was 10kW; you'd need batteries capable of doing that for however long those conditions exist on your ride--safest to just get ones that can do that continuously.
Using the ancient (and less capable/heavier/etc than modern cells) EIG C020 20Ah 5C cells I've got on my SB Cruiser trike as an example, along with those made-up numbers above (5kWh, 10kW) a 72v pack, 20s (20 series cell groups), would take about 70Ah to get 5kWh. (V x Ah = Wh)
At 20Ah each, you'd need 80Ah to get 70Ah, or 4p. So you'd have a 20s 4p pack, or 80 cells total.
"5C" means that the cell can supply 5x the amps that the cell has in capacity (Ah), so 5x 20Ah is 100A, continuous. (twice that for a few seconds at a time). So 4p of 100A cells means 400A continuous, or 400A x 72v = 29kW, so no problem with power output.
Each cell is about 410g, so about 33kg for cells, not counting interconnects, casing, compression hardware, etc. Call it 40kg for the pack weight (could be less).
They're about 216mm x 130mm x 7mm each, x 80 cells, which can be arranged however would fit in your available space, but you can figure out the total volume, and guesstimate if that would work without adding side panniers, or building a new underseat/overwheel enclosure that would replace the existing one that has the gas tank/etc in it, to hold the cells).
Modern cells are either better specs for the same size or smaller for the same specs, etc., so it would be a little smaller / lighter than the above for those specs, or more capable for the same size/weight. But it still wouldn't be really small/light.
But some are well-designed for some purpose or set of purposes actually useful to people that ride them 
