Question on Motor Controller Compatibility, and Troubleshooting

Hello All,

I have a question regarding motor controller compatibility for an existing E-bike kit supplied by Bafang USA Direct. In short, the problem is that this motor, and the motor controller that comes with, it is not designed to be capable of regenerative braking. We have made the necessary modifications at a hardware level to allow the motor to be capable of regen by replacing the existing free-wheeling clutch with a custom bi-directional clutch. However, we are currently struggling with outfitting the system with a new motor controller.

The motor controller, that we bought, and are intending to use, is the C4820-GR_Higo as supplied by Grin Technologies. We are having some issues with integrating this motor controller into the existing kit. All of the connections are designed to fit with our battery, the motor, LCD display, throttle, brakes, and lights that were present with the original controller. However, when we turn on the bike and attempt to use the throttle, we receive an error message, “Communication error” on the LCD display. We attempted all of the basic troubleshooting issues given on the distributors website, as well as re-setting the hall sensor per Grin’s suggestion to no avail. If anyone has experience with doing something like this, and has some suggestions as to how to get this to work, that would be greatly appreciated.

As a note, much of the difficulty with this problem has been the lack of any sort of documentation on the motor controller that was made by Bafang, and supplied with the kit. I have reached out to them and received no adequate response. If anyone has also found any documentation on Bafang products and their capabilities, that would also be greatly appreciated


Thank you in advance!


Link to Bafang Motor kit: https://www.bafangusadirect.com/Complete-Bafang-500W-Front-Hub-Motor-and-Battery-p/197.htm

Link to Grin Controller:
https://ebikes.ca/shop/electric-bicycle-parts/controllers/c4820-gr-higo.html

Perhaps you will actually reply to this thread, unlike your previous ones, to enable us to help you achieve a goal. :wink:

UCSB _emf said:

The motor controller, that we bought, and are intending to use, is the C4820-GR_Higo as supplied by Grin Technologies. We are having some issues with integrating this motor controller into the existing kit. All of the connections are designed to fit with our battery, the motor, LCD display, throttle, brakes, and lights that were present with the original controller. However, when we turn on the bike and attempt to use the throttle, we receive an error message, “Communication error” on the LCD display.

Click to expand...

None of the Grinfineon controllers have any way to communicate with an LCD.

They do have a multipin connector designed to connect to the Cycle Analyst (v3), but there is no communication on that connector.

So all the other things on your bike would connect to the controller (except whatever lights you have), and the LCD would simply be standalone and do nothing, or at best be able to read the voltage of your battery, and turn your lights on and off if it has connectors for those and a function to do so.


The LCD you have would need to be connected to a specifically-compatible (bafang) controller to work. LCDs and controllers are generally not intercompatible, and only work either with the specific controller they come with, or with a narrow range of specific controllers.

Hello amberwolf,

Thank you so much for the reply! I didnt expect that the communication with the LCD would be the problem. I guess that explains why the LCD could not display the proper charge on the battery when we turn the bike on.

However, something that still puzzles me is the throttle issues. The throttle does not work at all when the Grinfeon controller is connected. Could this still be related to the lack of communication with the LCD? Would we have to buy the Cycle Analyst from Grin in order to fix the throttle issues as well?

Apologies for my previous lack of replies. I'll try to me more active on this moving forward. I really appreciate the information you provided. My team and I are all mechanical engineers so this particular problem has been out of our range of experience.

UCSB _emf said:

However, something that still puzzles me is the throttle issues. The throttle does not work at all when the Grinfeon controller is connected. Could this still be related to the lack of communication with the LCD? Would we have to buy the Cycle Analyst from Grin in order to fix the throttle issues as well?

Click to expand...

No, any standard hall-based throttle should work on the Grinfineon...you just have to make sure it is wired correctly. Keep in mind that just because a pair of connector look the same, doesn't mean that they can be plugged into each ohter. There may be different voltages, wiring orders, signals, etc.

So there are a few possibilities for what could be wrong. We'll start with the worst-case most complicated:

Since the Grinfineon does not have a connector that you can plug the LCD into (even if it looks the same, the wiring is not), you'd have to show exactly how you wired everything up originally, wire for wire, and then also show how you have it wired now.

If the LCD plug and the GF "CA plug" are what you connected together, then there is a possibility that the LCD could have damaged the GF, by passing battery power where it shouldn't go. It depends on exactly which wires went where.

The CA plug has battery power output and ground wires, shunt plus and minus output wires, a motor hall output wire (for speedo signal), and a throttle input signal wire, all coming out or going into the controller.

A typical LCD plug has battery power input and ground wires, a keyswitch output wire that has battery voltage on it when the LCD is on, and two data lines. SOme of them have other wires in addition to this, whihc you'd need to know for your particular LCD.

If the LCD's plug and the GF's plug happen to line up so the battery power and ground wires are correct, and the keyswitch output wire of the LCD happens to line up with the throttle signal wire, then turning on the LCD will apply battery power to the throttle input. That's likely to damage the MCU in the GF permanently. If you also had the throttle connected correctly to the GF's throttle input connector, then the throttle itself is also likely to be damaged.

If the keyswitch wire happens to line up with the hall signal, then it is likely to damage both the motor's hall sensor and the GF's MCU.

In either of those cases, the GF itself would likely be damaged unrepairably, with it's brain (MCU chip) having damaged inputs required to operate it, and possibly worse internal damage to the chip from the high voltage on lines only meant to handle 5v or less.


Now, for the much better case:

You might simply have the throttle wiring in the wrong order. There is a 5v, a ground, and a signal output. Depending on the wire colors on the throttle, they may be one of a handful of common orders; the most common is that red is 5v and black is ground, and signal either white or green. (there are a bunch of other possibilities, of course). You can find out which pin is which on an unknown plug by measuring, using a 5v source (old usb charger, etc) and a voltmeter. For a Bafang type connection like BBS0x, it should be standard, and

If you have waterproof plugs on evertything, then if it does have the wrong wiring order, you'll have to either open the throttle's body up (often difficult and even moreso to reassemble) to rewire it, or you can cut into it's cable whereever is convenient along it's length, or you can open the controller itself up and rewire at the board inside.

I've attached a couple of BBSHD wiring diagrams I found via google; I can't guarantee their accuracy but you can use them as a guide to find out your specific wiring via testing.

The GF wiring should be in it's manual or on the Grin site.