First E-bike Conversion advice

General Discussion about electric bicycles.
User avatar
geoff57   10 kW

10 kW
Posts: 740
Joined: Apr 25 2007 5:32pm
Location: England

Re: First E-bike Conversion advice

Post by geoff57 » Feb 07 2018 8:49am

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

11spokes   100 mW

100 mW
Posts: 43
Joined: Mar 19 2014 9:58pm

Re: First E-bike Conversion advice

Post by 11spokes » Jun 20 2018 7:08am

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.

SkinZ   100 µW

100 µW
Posts: 8
Joined: Jan 07 2018 12:09pm

Re: First E-bike Conversion advice

Post by SkinZ » Jun 20 2018 2:04pm

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!

User avatar
Chalo   100 GW

100 GW
Posts: 7415
Joined: Apr 29 2009 11:29pm
Location: Austin, Texas

Re: First E-bike Conversion advice

Post by Chalo » Jun 20 2018 2:12pm

11spokes wrote:
Jun 20 2018 7:08am
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,
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.
This is to express my gratitude to Justin of Grin Technologies for his extraordinary measures to save this forum for the benefit of all.

User avatar
amberwolf   100 GW

100 GW
Posts: 25691
Joined: Aug 17 2009 6:43am
Location: Phoenix, AZ, USA, Earth, Sol, Local Bubble, Orion Arm, Milky Way, Local Group
Contact:

Re: First E-bike Conversion advice

Post by amberwolf » Jun 20 2018 10:58pm

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.

Post Reply