First E-bike Conversion advice

Sorry for the late response I understand what you mean when you say voltage sag I’ve worked with Pb battery’s and most of them had huge voltage sag, I have bought bikes with supposed ok Li ion batteries they had the same problem and a steady voltage drop over a short distance with a rise once I was stationary!
Geoff

Hi,
I just purchased a voilamart kit with the lcd display. Just wondering how the lcd will give me an accurate speed detection, as there is no magnet or sensor with the kit, does the speed sensor work through the hub motor? Just interested to know as I’m not sure how this works.
Any help would be great!
Thanks. Ben.

Mine didn't come with one of them so I can't tell you. Maybe it calcs from watt/volt/amp draw? Good thread resurrection tho! Currently running my 36v voilamart on 14s @ 57ish volts with no problems. Just in case you wanted to have a go!

11spokes said:

I just purchased a voilamart kit with the lcd display. Just wondering how the lcd will give me an accurate speed detection, as there is no magnet or sensor with the kit,

Click to expand...

The controller "knows" the motor's RPM, so it's a relatively simple matter for it to extrapolate a road speed based on wheel diameter. (This method only works for a direct drive brushless motor.) There is probably a parameter setting for wheel diameter in the display unit.

And if it's a geared hub, then it can (lke my Fusin) have a speed sensor on the inside of the casing that detects speed of the outer motor shell (and thus the wheel itself, rather than the motor speed). This usually means having 9 wires in the cable vs 8, for a sensored motor, and 6 wires vs 3, for a sensorless.