Hello, new guy here. I was introduced...

[charlied63]

to E bikes by a friend who sells and services them here in Michigan. I have been a bike wrench for awhile now, so he asked me to wrench for him in his E bike shop. While completely new to me I really liked the idea of an electric bike. I ended up converting my Surly Troll, I run a Bafang rear hub motor and a 48V 12Ah Samsung frame pack with no pedal assist hooked up. I am picking up on this stuff real quick, but am real new so please bear with me when I ask seemingly dumb questions....like this one.. Am I to understand I can eliminate the hall sensors if I am not running pedal assist? I ask based on an article on this site I read about putting bigger wires and running an oil bath cooling on the geared hub Bafang. Thanks in advance and great site!

 

[Drunkskunk]

Welcome to the forum.

No, you need sensor wires unless the controller is designed to run sensorless.
BLDC motors don't work like a a more conventional motor. you can't just hook a battery to them and have them turn. The coils need to be told exactly when to fire to get the motor spinning in the right direction and keep it spinning. It's a lot like the spark plugs on a car. they have to fire in the right order at the right time or it won't work. The controller handles that.

A sensorless controller is very good at guessing when to fire the right coils. There's some tech to it, but basically it's just a guessing. There are some down sides to sensorless, but the up side is you don't need the extra sensor wires.

 

[charlied63]

The sensors I am talking about are internal to the motor. I read about eliminating them in a post on here by "spinningmagnets" in June of 2013 titled "Bafang/BPM geared -hub specs, teardown and pics" In that post in the section about doubling the phase wires copper to allow more amps to be used he mentions cutting the 5 hall sensor wires for sensor less operation and using 3 of the 5 wires for a temp sensor. I am new to this and was thinking about how to up the wire size when I came across this site. I really like the mods he did to the hub as far a bigger wires and oil cooling, but am real curious about the mentioned sensor less operation. Thanks again.

 

[ecycler]

You will need a BLDC sensorless controller if you want to clip the hall wires in the motor. Try unplugging them to see if your existing controller is capable of running sensorless and see how well it starts from a stop.