Can we use extra functions on low cost ebike controllers?

Jeff23spl

10 mW
Joined
May 22, 2023
Messages
23
Location
Quebec
I opened up few bldc controllers and there is often empty slot on boards for extra wires not connected. Can it be free functions that can be used if i add wires to it?

I got 2 replacement controller for my ride, one with a display to add some fun but the other doesn't have wires for a display. Can i find RX/TX on the board and make it work with a display or is there many communications protocol and it won't work if the display isn't the same brand ?

The one with display doesn't have 3speeds switch wires and i need this feature because in some conditions i want to limit speed and make the throttle less sensitive. is there good chances i find free connection for that feature or if a controller having PAS feature aren't made for 3 speed switch ?

I ask if i can help one of the 2 controllers to better suit my needs. If i use one with display i lose my 3speed switch and less current but if i use the other, i won't have display...

Assuming there is free function availaible, is there a common meaning of abreviations about board text written ? I found a youtube video where the guy mess around with a multimeter and say if you measure 5v, it is a free function but can we sort it out first by the text there to know if the function exist ?

Also one of them was sold as a 48/60/72/84v and translated description was looking like the controller would choose by itself my battery voltage...Once i opened it, i can see a place to solder a jumper to select voltage with only 3 choices 60-72-84
I assume the controller isn't bothering much about using higher voltage if it isn't too high for internal parts but what about low voltage cut off? Can it really auto choose it or it was a scam of translating error and i need to set it by soldering the proper jumper ?
Problem is that the lowest setting is 60v, and im using a 14s pack...I wonder what would happen if there is no jumper at all, will it default 48v or not have any cut off at all? At worst i have room to rise it to 16s but would need a new BMS

I was also wondering if basic controller with a 3 speed switch has flux weekening since it claim the high speed selection to be 120%......That would be nice but i would not be surprised either if instead, it makes the default middle speed at 20% reduction from natural kv and connecting high speed just return to full range up to maximum motor kv as the stated 120% speed....Is any of you have ever tested this with a refference natural motor rpm ? Maybe i could compare my contorller with PAS maximum rpm against the one with 3 speed switch to figure it out but if someone know the answer, i would be interested to ear it.
 
Btw the controlers im talking about are the basic low cost models found on ebay/amazon with a rectangular full aluminium body with bolted end caps. (Not the more expensives and programmable ones with usually bolts to connect power wires)
 
There were some people trying to get extra stuff from the hksun seller on ebay. The title of the thread on e.s. was something like $14.99 48v controller, they went deep. Found the pcb supplier, and one guy trying to hack the tx/rx pads. Worth a search on es for that excellent relateable thread.

This might be it.
 
I opened up few bldc controllers and there is often empty slot on boards for extra wires not connected. Can it be free functions that can be used if i add wires to it?
Maybe.

You would have to experiment to find out, with the risk of damaging or bricking the controller.

Generally "function" wires (like reverse, regen, antitheft, speed limit, etc) are signal inputs that you connect to ground to activate, or leave disconnected to deactivate. (not always the case, and must be tested to verify in every case).

If you dig around, there are a bunch of threads around the forum over the years with info on what some controllers have been tested to have for functionality of various PCB pads...but the terms marked on one PCB may not mean the same as those on another..so no guarantees that any existing information will apply to any of your controllers.

If you look thru my posts from yesterday, in another thread I linked one of my controller threads with info for that specific controller.

I got 2 replacement controller for my ride, one with a display to add some fun but the other doesn't have wires for a display. Can i find RX/TX on the board and make it work with a display or is there many communications protocol and it won't work if the display isn't the same brand ?
The latter.

Generally controllers / displays are not intercompatible, either because of protocol or because of data being sent not matching up. But a controller that doesn't have wires for a display, even though it has pads for them on the board, might not have firmware that sends or receives data on them.

You can still try it and see; as long as the wires are correclty hooked up it's unlikely to damage anything, but it's more likely to not work than to work. (display connectors generally have both battery voltage and low voltage signals; if mixed up things can go POOF).



The one with display doesn't have 3speeds switch wires and i need this feature because in some conditions i want to limit speed and make the throttle less sensitive. is there good chances i find free connection for that feature or if a controller having PAS feature aren't made for 3 speed switch ?

There is a chance of almost any feature being present but not wired out, but how large that chance is, I don't know.

You can actually make your own three speed switch function for any controller. A post I made earlier tonight in another thread describes how to wire a potentiometer between throttle and controller to reduce it's signal to the controller, and how to make a bypass switch for it, which gives you two speeds. If you need more, just create one less pot circuits than speeds you need (full speed doesn't use one), and use a rotary switch (or other multiposition switch) to change between them.


I found a youtube video where the guy mess around with a multimeter and say if you measure 5v, it is a free function
Not necessarily. It could just be 5v supply. If you then ground that (which is used to activate most features that have 5v pullups), you can damage the 5v power supply in the controller, which could cause it to not work right or at all.


Also one of them was sold as a 48/60/72/84v and translated description was looking like the controller would choose by itself my battery voltage...Once i opened it, i can see a place to solder a jumper to select voltage with only 3 choices 60-72-84
I assume the controller isn't bothering much about using higher voltage if it isn't too high for internal parts but what about low voltage cut off? Can it really auto choose it or it was a scam of translating error and i need to set it by soldering the proper jumper ?
It probably has an autodetect, but you would have to test it by running down your battery to the expected LVC and seeing if the controller stops responding when the battery goes below that level. If it keeps going, it's not using the right LVC for whatever reason.

That autodeteced voltage level is for the LVC to protect your battery.

If a controller is built for say, 48v, and you use it with a 60v battery, it would probably operate (if all the parts can handle the ~72v full charge; cheaper ones probably won't for long), but becuase a 60v battery is empty at around 52v, and the controller is expecting a 48v battery to be empty at about 40v, so the controller won't shutdown to protect the higher voltage battery. If the battery has a working BMS, it should protect itself, but since the BMS is an "emergency" protection device, in case all other protections fail, it shouldn't be relied on for everyday protection. Doing so is harder on the battery (and the BMS) and there can be other consequences besides just aging the pack faster.

If a controller states it's actual max voltage, then that is a voltage limit you shouldn't exceed or risk damage to controller. But generally they only state the "type" of battery they are for--36v, 48v, 52v, 60v, 72v, etc., and those tell you more about the LVC than what the controller can handle.


Problem is that the lowest setting is 60v, and im using a 14s pack...I wonder what would happen if there is no jumper at all, will it default 48v or not have any cut off at all? At worst i have room to rise it to 16s but would need a new BMS
Leave it as is and test. If it doesn't do what you want, experiment. ;)

I was also wondering if basic controller with a 3 speed switch has flux weekening since it claim the high speed selection to be 120%......
It would have to be an FOC controller to do FW. (some Lishui LS controllers are). Which means it has to be programmable (even if only via a display, but usually by a computer-based program and/or a BT-device app), so you can tell it what the motor parameters (kV, inductance, resistance, pole count, etc) are so ti can correctly run the motor. At the least it requires an "autotune" procedure that gives you a result you can manually correct if it doesn't work like it should.

For the typical generic controller, the 120% is usually the real 100%, and they're just using marketing (lies) to make it sound better than it actually is. ;)
 
Maybe.

You would have to experiment to find out, with the risk of damaging or bricking the controller.

Generally "function" wires (like reverse, regen, antitheft, speed limit, etc) are signal inputs that you connect to ground to activate, or leave disconnected to deactivate. (not always the case, and must be tested to verify in every case).
Made somme testing but not all the one i had in mind because i ran out of time.

The larger controller multi-voltage is cutting out at 40v in 60v config and without any selection it is still 40v. at higher selection, it cut off at higher voltage obviously. It could have been ok for my 14s but not ideal for 13s or less. But there was not spare wires talking about communication for my display. and it was a bit large to fit.

I made a shunt mod on the other one with display. I spend a lot of time playing around to understant parameters and functions. It was turning backward and i did burn it trying to find a sequence to change direction. i did that kind of try and error before with another controller without burning it but with this one as soon as a did try the wrong sequence, it made a noise and bang, 1 group of fet was short...in fact just 1 of the 2 fet shorted.
i took 2 from another controller, i wonder how bad it would be to run 1 group out of the 6 to be slightly different. at least i matched the pair....i tryed to find spec and got few different results for internal resistance and it was close to the others....it works...

To avoid burning it again, i put resistances on 2 of the 3 motor wires to lower current. i had 7ohm in hand, it was a bit high but it worked...i found the right sequence without hurting it anymore.


For the 3 speeds switch, you are right, i can arrange it by the throttl. I did that for a brushed controller and it worked. but i found that i have access to 5 different speed to select from the display itself so i won't need it. And this controller is way more smooth at low throttle input.
I tuned my shunt mod a bit to lower current to 40A (specs was telling 36A) it should last. curiously, there is a current setting in the display but regardless i set it to 1 or 20 i keep having the same maximum current. and it isn't battery limit because initially, i was going up to 60A before i remove some material around the shunt....But thats fine...

Next week i will ride a lot with it to make experiments.
 
Back
Top