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Discussion Starter · #1 ·

I want to connect a BLDC motor (48 V 1500 W), with a Kelly Controls KEB48201X,

I have not worked with wiring BLDC motors or any such motor controller before. I went through the manual for Kelly controls but, I am stuck with the main contactor circuit and other circuit related issues.

I am having a battery pack of 24V, ordered a contactor rated at 48V from Kelly controls website, not sure if it will work properly with the supply voltage(just assuming it should work fine at any lower voltage than rated).

If anyone can guide me regarding this it would be a great help!

Thank You

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Discussion Starter · #4 · (Edited)
I contacted Kelly controls support and they sent me a simple wiring diagram without any contactor , telling me it is not necessary but they still recommended, but the user manual is having a wiring diagram with the contactor and precharge resistors in it.

Also I read about the precharge resistors and how it helps from damaging the controller, so I am confused to whether I should use it or not.

Simple wiring diagram that Kelly controls support sent me:

The wiring diagram in manual (page 11)

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Discussion Starter · #5 ·
Yup, we need more info
...a lot more info

Quick question:
Why would you/anyone purchase a 24V battery pack power a 48V motor?

If it does work (or function) it will only be able to give your motor ~50% of what it wants & is designed for
...a 48V battery pack is what you need

You shouldn't need to use a contactor on a 48V 1,500W motor.

Contactors are usually only used on motors that are over ~3,000W

Since I can't direct you to ANY of my old threads (at the moment)

Here is a You Tube video of a go kart that I put a 48V 1,800W BLDC motor on

Hope it helps
If you have already got it working without the main contactor then I should be good without it .
So I am guessing the wiring will be pretty much similar to yours on Kelly controller too?

Also I am working on this project as a part of a summer program so, the guys here already had these controllers and motors used by a previous group, but the previous group could not get it working due to some problems, also there is no documentation made by them on what went wrong.
Regarding the battery packs, that's all I have here that I can use around 36V if not 24 V is the max I can get the motor to work with.

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Discussion Starter · #8 ·
Contactors are (usually) necessary or used for
...high amp systems (60V & up)
...or if, using big (high wattage) motors (over ~3,000W)

The specs says for your KEB48201X speed controller says:

"Supply current, PWR, 150mA.
...the speed controller (itself) draws 150mA.

"Controller Supply Voltage Range 18V - 90V"
...that's the voltage range that the speed controller can handle

"Configurable battery voltage range,B-. Max operating range 18V - 60V", anywhere from 24V - 48V should power it

* Different manufacturers do things "differently", you/we'll have to go by the Kelly diagram

* I have had many conversations with Fran @ Kelly Controls
...she is very helpful (but, can't help everyone "step by step"
...that's what were here for (I think)
So should I just go ahead and wire up like the simple wiring diagram as suggested by the Kelly controls support ( Fany ).

As a newbie to this, this is really confusing with no clear and solid guides on which wiring to follow.
Could you please give any links to guides that we should follow to get this to work !

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Discussion Starter · #10 ·
The battery packs that I was given are rated at 12v with peak current of 10A,
of even if I connect 3- 4 of them in series to generate 36~48v, the max current that I will get is still 10A, will that be enough even to just start up the motor?

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Discussion Starter · #12 · (Edited)
What kind of batteries are we talking about?
...with a peak current of 10A?

I have pulled 100A out of (4) 12V 12AH SLA's (many times)

Also, what (make/model of 1,500W BLDC) motor do you have?

Your speed controller has a max current of 160A & a continuous current limit of 60A

But, keep in mind that your 1,500W BLDC motor should draw about the same as the 1,800W BLDC on the e-Lemon-aid kart (in the video that I linked earlier)

The meter showed that it drew
...~30A @ take off
…& ~10A consistently
The batteries I have are universal SLA rated at 12v, ~30Ah and initial current rating at 10 A.

The motor is BLDC-108, 48 V 1500W
According to the performance report the motor draws close to ~35A on lower rpm operation, which is how I intend to use the motor.
Also is it possible to run the motor at rpms lower than those stated in the Detailed Parameters section RPM 3200- 5000 ?

Thank you for taking time and helping me out !

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Discussion Starter · #14 ·
Your very welcome

Those batteries should power that motor & controller, just fine

I don't have any knowledge of that specific motor
...but, (as I said) a 1,500W BLDC should have "roughly" the same characteristics/performance as the 1,800W BLDC (in the video)

Your motor may draw ~35A at take-off but should drop considerably once it's/your "up to speed"

The speed controller is how "you" control the RPM's of the motor

0 throttle = 0 RPM's = full stop
1/4 throttle = 25% RPM's = 25% available speed
1/2 throttle = 50% RPM's = 50% available speed
3/4 throttle = 75% RPM's = 75% available speed
Full throttle = 100% RPM's = max available speed

* Also, these Kelly controllers are "configurable"
...which means that you can "go in" & make adjustments

(don't worry about it right now, we'll get into that later)

Do you have the "programming cord" to connect the speed controller to a computer?
I have a programming cord for the Kelly controller, but I don't have a speed controller, I was planning to use the throttle input on the Kelly controller to control speed, I hope that's what you are referring to as speed controller.

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Discussion Starter · #16 ·
The KEB48201X is your speed controller (brain box) controls the power (amps) going into the motor, which dictates the speed (RPM's) that the motor turns.

You control the motor, thru the speed controller, with a throttle.
...that's what connect to the throttle input

The throttle can be either
...a twist throttle (like on a motorcycle, on the handle bars)
...a thumb throttle (like on an ATV or jet skis handle bars)
...or a pedal throttle (like on golf carts)

Here is an example thumb throttle

Do you have a throttle?
Yeah I am having a twist throttle, I am almost done with the wiring for the motor, just left with getting a key switch for connecting between the battery pack and the B+, I was wondering if that is really necessary because I already have a contactor in place that can also act as a switch. But still going to get that switch just in case.

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Discussion Starter · #18 ·
Yes, a switch between the battery & speed controller is necessary. gives you the ability to turn the speed controller on or off.

It doesn't have to be a key switch, any 12V toggle switch will do this circuit will only be carrying ~150mA.
(using a key switch allows you to secure/lock your project)

The contactor is a totally different switch is a "big/beefy" switch between the speed controller & motor
So I got everything connected according to the manual, and the connections you posted before.
The controller flashes red and then there is no led lights on, according to the manual the controller should flash red twice and then green led should stay on indicating normal functionality, but in my case the green led stays off.

I checked the manual for anything regarding this behavior and found that there is on line on page 11 saying we need to check continuity between PWR and Ground, but they did not explain what to do next.

Also the manual has pages of error codes but there isn't one that matches mine.

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Discussion Starter · #20 ·
Well, that sucks!

I think you just found "the spot" where the other group got stuck
(the one that was previously working with this controller & could not get it to work)

Are you sure the controller even works (Dumb question, I know)

I guess now, would be a good time to open a dialog with Fany @ [email protected]

Let her know "I think she's a her" that you followed the diagram, that she referred you to, explain everything that you have done & what happened when you switched it on.

Let us know how it goes.
I tried connecting it to the computer to see whether the controller is fine, and then I got the error code for low voltage and hall sensor error.
I shorted the terminals for MicroSW and RTN as shown in the wiring diagram with the throttle wiring, I got an error code for throttle voltage exceeding required voltage ( shorted microSW(5v) with rtn which is max throttle during controller startup according to the manual this must give an error code, which I could verify).

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Discussion Starter · #24 ·
If the controller senses (receives) lower than required voltage
...the "low voltage protection" function would "kick in" (no green light)
(to help protect your battery pack)

The green light only lights when everything is functioning normally's main job is to tell you, "if" your good to go

1.) What is the voltage, that you have, going in to the controller?

2.) What throttle do you have

3.) & how do you have it connected?

It always makes me shiver when someone says "I shorted..."

...always use a small fuse (like 3A or 5A)

That way, if it's a mistake (hopefully) the fuse "pops" & not the component that your testing your "idea" on
48V going into the controller
I am having a twist type throttle like in a bike

I had screwed in the connections properly during testing, I just took these pics after I had disconnected it from the batteries, that's why B+ and B- terminals are not shown screwed in.

These were the pics I sent to Fany(Kelly controller support)
The controller just flashes Red then there is no LED ON, ideally green should always stay ON
video -

The green LED flashes green and turns off only once, if we try to power on the controller again on the same day it will never turn on the green led.

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Discussion Starter · #26 · (Edited)
So I tried connecting the controller with my PC as shown here,

Now I get the error code for Hall Sensor error and low voltage till, green led is not solid ON as shown in the website.!ApUrq55G9ocHlW_5xwDctMuH1fbo

I connected it according to the instructions in the manual, (B- is disconnected from the battery pack, only PWR and RTN connected).

It is even recognized by the software and I am able to change the config, low voltage is set to 18 V, I am applying 48 V so that is not a problem

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Discussion Starter · #28 ·
Speed controllers (most electronics) have "safe"/usable" voltage ranges
...because the voltage changes as the battery is drained.

The voltage level of a 48V SLA battery pack goes from
...~53V (fully charged) ~40V (lowest level you can "safely" drain the battery down to without damaging it)

Safe voltage ranges
(for most SLA's)

12V = 10V - 13.3V
24V = 20V - 26.6V
36V = 30V - 39.9V
48V = 40V - 53.2V
60V = 50V - 66.5V

So, maybe try
...setting the low voltage ~40V & the high voltage ~ 53V

If you still get hall sensor error maybe
...disconnect the throttle
Yeah my combined battery voltage is ~52.
The default settings in the controller is 18V for low voltage and 70V for high voltage.

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Discussion Starter · #29 · (Edited)
So I finally got the motor working :)
Seems only the green led is faulty (thankfully) as it sometimes lights up and goes off randomly with the motor still running regardless of the green led.

It was the throttle that was the issue, just replaced it with a simple 5K potentiometer and it started working.

And after this I connected the throttle to pwm output of Arduino to control the motor wirelessly and that too works. I hope giving pwm (max 5 V) to throttle pin wont do any damage in the long term (atleast till the day of the demo :p).
I am applying just around 0.125V (max) through pwm to keep the max speed as less as possible, also I have programmed the controller to run at 50% speed.

How to electrically brake the motor with the current setup (without regen might not need that at the moment)? Right now I am just cutting of the pwm signal from the throttle (giving pwm 0% duty cycle) to stop the motor.
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