E-Scooter (Tandem) build. Looks great, but doesn't go.

Steve360

1 µW
Joined
Jun 22, 2024
Messages
3
Location
Barcelona
Hi, I am new to this Forum, so hello to everyone.
My first E-Scooter (Tandem) build has me banging my head against the wall, it looks great but doesn’t go. I built it using parts from a Chinese electric scooter and a traditional 26 inch bike. It's really a scooter, but disguised as an E-bike. I am a competent mechanic and auto electrician when it comes to classic cars, but speed controllers and BLDC motors are all new to me. While I think I understand it, I am definitely missing something.
I’ll try to explain briefly what what I have created. I have a 48v 1400w BLDC hub motor with a 48V 1500w speed controller, powered from a 48v 100Ah Lithium-ion battery and the standard Chinese scooter twist throttle.
From the battery, I have a Pos & Neg going to the Pos & Neg on the Controller. I have bridged the key switch wires from the controller (Red & Orange). I have connected the Red/Black/Green to the Red/Black/Green of the throttle. I have connected the Yellow/Blue/Green phase wires from the controller to the corresponding phase wires on the motor. Finally the Red/Black/Yellow/Blue/Green hall wires from the controller to the corresponding hall wires on the motor. But I have no life from my machine.
First I bought a new controller thinking this was the problem, but it’s still the same. I then recently I bought an E-Bike testing device. With the new device I have perfect test results from the throttle, motor phase and hall sensors, all shows up good. The only negative result was the controller, when tested, doesn’t light up the 5V output LED. I then tested the 5v output with a multi meter and I am only getting an output of 2.76V. Which in return from the throttle when ‘closed’ reads .82v and ‘fully open’ reads 1.98v. So my question is, should the motor turn slowly with this low voltage or is it normal that it doesn’t turn at all ?
Thanks in advance to everyone reading this. Steve.
 
I've found lots of bad connector pin crimps on many controllers and throttles. The first thing I do now is take the pins out of the connector body and make sure the wire was stripped and crimped properly. A little solder will ensure a good pin connection, very little so you don't ruin the pin with gobs of solder. Also check to see if your controller has a 3 speed switch, because this will limit the amount of voltage that goes to the throttle. I had to add a jumper wire on a controller 3-speed switch to get the full throttle voltage. Throttle Testing Guide - ElectricScooterParts.com
 
You should have at least 4.3v on the 5v line. Something is pulling it down. Try disconnecting the throttle and read the 5v line. If still low, try disconnecting the the motor halls. You could have a bad throttle or motor hall. If it still reads low after disconnecting everything, the controller is bad.
 
Hello gmac3211 & fetcher, Thank you both for your inputs. Unfortunately I am on holiday for 4 weeks, 2000 miles from my tandem, so I cant test anything until I get home.
I will get back to you once I have tested your suggestions.
Thanks again, Steve.
 
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