Derestricting a hardwired speed limiter

Fort Ord

New Member
Sorry about the relative ignorance here. I bought a DJ mountain bike, 48V "750w" rear hub Bafang motor. Great ride, nicely made bike, very reliable. That said, the thing is limited to 20MPH.
Is the controller the limiter on speed? If so, does anyone have a suggestion on a replacement controller where I can set my own parameters?
Your help is greatly appreciated.

Many thanks,
rd
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Pretty sure an aftermarket controller would do what you are after. When installing an after market controller, the issue is matching up all the wiring on your existing bike to that of the controller. While possible, it's going to be beyond many abilities. There's not even a universal wire color code, so there's not even assurance wire colors will match up on both sides of each connector. -Al
 

harryS

Well-Known Member
This one?

I have no experience with your bike, but many inexpensive import ebikes with LCD displays have a max speed setting in the LCD setup. In the above listing, someone asks the question about top speed. DJ bikes says 20 mph, but a customer says she set her LCD higher and got 24 mph. Sounds about right to me,
 

Fort Ord

New Member
Hi, thanks. I did the LCD adjustment, with no improvement. The owner of DJ bikes told me "the 20MPH limit is hardwired in, cannot be changed." Thus my question about replacing the controller, display, throttle, etc.
 

rich c

Well-Known Member
Hard programmed maybe, but there is no hardwiring. As others, I have no idea what controller you have, and if there is any proprietary protocol language between your controller and the display. You also need to know what size controller you have. If something like a 15amp, then it won't pass enough current to go much faster. Your best bet is to buy both a controller and display that is programmable and of course it's the easiest when the connector to the motor matches the controller. Buy at least a 20amp, or even a 25amp controller. I suggest you contact Luna, Bolton, or Electrobike World with a picture of your motor connector.
 
  • Like
Reactions: BET

Fort Ord

New Member
Hi, Rich C., thank you VERY much for your rational response. I plan on doing some disassembly to see what the specific controller I have on the bike. Funny thing though - the motor itself is a Bafang RM G070.D 13, and I cannot find ANY information on this motor from the web, or the Bafang site. I hope the installed controller is a normally available commercial model...
 

kmccune

Active Member
I had a "Maxfoot" cruiser with the 750 watt Bafang, it had the Fatires and weighed 82# with a 26 amp controller it would do 28 mph easily and it pulled good on the Hills, this motor would "max" out at 1050 watts and of course one of the first things I did was derestrict if I remember correctly, did have to replace the controller, the first one only worked for speedo reading.6 of a mile, the second one worked when it felt like it, never had any trouble with the PAS you never needed over 2or 3 on the steepest hill, PAS5 with the 11tooth gear would go to fast on a slight downgrade.
My daughters 48 volt ecotric will only run around 20 mph no matter what, the good thing about when I compared it to my XP was the endurance on the battery. The XP would run 28 mph derestricted ,I have a feeling that 20 mph is a whole lot better on battery life.
 

Fort Ord

New Member
Ah. Thank you for this! Yah, my longest commute here is 11 miles each way. I'll try the controller replacement and see what happens.

Much obliged,
rd
 

kmccune

Active Member
Ah. Thank you for this! Yah, my longest commute here is 11 miles each way. I'll try the controller replacement and see what happens.

Much obliged,
rd
You are welcome, I am not sure but keep this in mind some displays seem to have an effect on the system as well.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Yes, without a doubt. Many (most?) controllers are purchased WITH a display as that display is proprietary to the controller. Further, that display may be the only way to program the controller.

Are you considering a controller upgrade project with the idea that some wiring changes may be involved? ?
 

kmccune

Active Member
This is not "Ford Ord" asking-its "Plain Kevin McCune".
How do you tell if a particular display is compatible with a certain controller?
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
I wish I knew more about that. What I do know is that even if a display will plug in and light up when turned on, the communications between the controller and display may not work due to different protocols/languages used by each.

I've been using aftermarket KT based controllers and displays (LCD3) since my first build. I know that the KT displays will work only with a KT controller - unless you're a wizard able to figure out code using open source software that's WAY above my pay grade.... -Al
 

kmccune

Active Member
So, the KT controllers will work with the LCD3 all the time?.Cool. I checked on Ali Express , these must be a default display,it looks like the ones I usually get with an EBike.
 

harryS

Well-Known Member
How do you tell if a display works with your controller? Buy them together. If I ever do any future builds, I would use KT controllers.
 

kmccune

Active Member
How do you tell if a display works with your controller? Buy them together. If I ever do any future builds, I would use KT controllers.
Sometimes we may have a leftover controller or display, cost figures in occasionally, perhaps a table at a yard sale,I know I have stuff I will giveaway or sell cheap.
 

AHicks

Well-Known Member
Region
USA
City
Snow Bird - Summer S.E. Michigan, Winter Gulf Coast North Central Fl.
Not all projects are going to need a speed sensor. Direct drive hubs will not. The ones that do need a sensor most often are geared hubs. Many of those are equipped with a speed sensor, the problem being the speed goes to -0- when coasting. Reason being the motor is clutched, so they are easier to pedal when not under power. Down side is there's no speed signal if the motor isn't turning.

No big deal, external speed sensors are inexpensive and easy to install. -Al
 

harryS

Well-Known Member
Just a few suggestions Ft. Ord, Unless you're a soldering whiz, you save time finding a controller that matches the motor cable. I never liked splicing that cable. Many Bafang motors and many others use a 9 pin male connector like this one.,
P1120248.jpg

Some of the more powerful fat bike motors use a larger female connector like this.
Big9.jpg

If you pick a controller with the same motor connector, it will probably match pin for pin. If you're really lazy, buy it with the brake levers, display, PAS sensor, and throttle. Then all the peripherals match, and it doesn't cost that much more. You could then pull your old controller and use it on another ebike when you get a motor.

ANd since you want more speed, go for a 22A-25A controller. It probably won't fit in the frame like your old one. Put it on the downtube with a plastic controller box for a clean look,

P3291822.jpg