My bike suddenly goes backwards

[Sm00th]

Hello!
I just completed my first bike build. 3 wheel cargo bike.
I bought two electic bike kit. 2 front wheels has each a 1000W direct brushless motor with each a Chinazipu Elektronikbox, 48V 22A.
4 batteries each 12V12Ah
I ran it for an hour. It ran perfect. So i took it back to recharge and better tuck and fasten the cables. But now an hour later next run the left motor directly stuttered and after 2 min it changed direction and now only runs backwards. So i ran on the right wheel. After 10 minuts it also started to go backwards... now the bike Only runs backwards?!

 

[dingoEsride]

Does it run as fast backwards as it did before, if your controller has a reverse function the two wires only need to make contact to go in reverse or check your phase wire connections

 

[Dauntless]

Brushless. Does it have hall sensors? Answer that and you'll really start getting the suggestions here.

 

[RLT]

If the controller has a self learning function, make sure that it is not enabled (usually two white wires with black connectors, plugged into each other)

 

[Sm00th]

Thank you for replies!

I think it goes slower backwards.

I attached this new picture. If it helps?

 

[amberwolf]

There is sometimes a reverse wire pair that when connected will cause what you see. On SB Cruiser (see link in signature) it has such a pair hooked to a button on the handlebars for the righthand controller/motor (there isn't one for the left controller). Makes backing up a lot easier than pushing with my feet (since I can't pedal it backwards), especially up any kind of slope.


Another thing that can cause what you see is a self-learn wire pair, that when connected will first try to turn the wheel one direction, then the other. Some of them do it only when you apply throttle. Some do it automatically. Some even go forward for the lower half of the throttle, then when pushed higher than halfway it goes in reverse (only when t he learn wires are connected).


Another thing that can happen is if the hall wires become disconnected or have a bad connection, a controller can get confused and either try turning the mtoor the wrong way (this usually doesn't move the bike and jsut grinds and can damage things if high throttle is applied during this problem). Or the controller can revert to sensorless operation, and some of those might turn the motor backwards if it's moved backwards at the instant of startup, getting confused about the direction it was supposed to be moving it.


Also, if the phase or hall connectors are individual pins rather than all in a single connector, then if you changed which wire went where, even by accident, it would change the order in which the controller runs the wires and so the direction of the motor (or how it runs, smooth or ragged). This can be fixed by re-runnign the self-learn fucntion if it has one, otherwise you have to put them back in the same order they started out in.

 

[Sm00th]

Ok thank you. I will try when I get home. Here is another picture I had.

 

[Sm00th]

It works!!! I briefly connected the pink cables. Thank you all so much. I was lucky I found this forum!

 

[d8veh]

It most likely has self-learning and you left the self-learning wires connected, so each time you start up, it re-configures its assessment of your motor. You do the self-learning procedure, and when it gets the direction correct, switch off and disconnect the wires to keep that configuration.