mbgjt1 wrote: ↑
Nov 20 2020 4:01pm
As you can see it would take 9.26 seconds to accelerate from 0 to 80.7 kph. Does with match up with real life results? It seems abit slow. How can I reduce this time to 5 seconds or less? The motor will be mounted at the back wheel as a hub configuration, not a mid drive.
Any advice? What am I missing?
I've noticed it takes about 4.299 seconds to accelerate to 66 kph, which is still slow. I am hoping to achieve sub 5 second acceleration to 80 kph. Is this unrealistic in this configuration?
I think the grin simulator is pretty accurate, but the parameters you use make a big difference. For example, battery internal resistance makes a big difference in that calculator. You used 0.2ohms. Where did you get this figure ? Look what happens when you change it to 0.1 ohms (for example). Oh and also you could use maximum battery voltage if you're looking to figure out maximum performance. The calculator will adjust for sag (based on the IR). See here: https://ebikes.ca/tools/simulator.html? ... &kv_b=15.6
Where did you get your spreadsheet data from ? It's a bit hard for us to verify it without looking at the actual data.
FWIW, my bike (26" wheel, 20S5P VTC6, 140kg, MXUS3k4T (Kv=9.2rpm/V, kt=1.04Nm/A), Nucular 12F @ 150Ab & 250Ap, field weakening on) does:
0-20km/h @ 1.4 sec
0-40km/h @ 2.8 sec
0-60km/h @ 4.9 sec
0-80km/h @ 8.6 sec
0-100km/h @ 20+ sec
Field weakening really changes things (it really boosts torque in the upper rev range) and unfortunately you can't replicate that in the motor simulator. This is my (non-FW) setup in the simulator, and it's pretty close to reality (you'll just have to trust me on that, I don't have any saved data to show you a comparison): https://ebikes.ca/tools/simulator.html? ... &wheel=26i
I have compared it in the past, and if I recall correctly, it's within about 10 or 20%. It'll really depend on data you use in the simulator, and conditions during your road test.
This is logged data (with FW on) vs the simulator data (non-FW). As you can see, it's apples to oranges:
If you take your simulator plot and overlay mine (and add a bit of top end for field wekening), they're pretty close, so I'd say your estimated times (which are pretty close to my logged data) sound like they're in the ballpark of 0-80 in 8-9 seconds.
But I strongly doubt you could half that 0-80 time like without difficulty. It would require a significant increase in power.