E-Bike Controller without speed limit? 48V 1000/1500W

Hello members of Endless Sphere!

TL;DR is below

I'm having a lot of trouble with those stupid speed limit functions in each controller. :? When I first bought an e-bike conversion kit with a motor rated for 48V and 1000W, it came with a controller which had a 20mph speed limit integrated, and there were no output wires which I could short or disconnect to disable the speed limit. The ebay seller from whom I bought this kit claimed the motor could easily reach 28mph (45kmh) on full power without peddling, but it can't since the speed is limited to 20mph. This annoyed me, I've been searching for ways to disable the speed limit since I got my kit and invested a lot of hours into it. (Removing the controller from the bike, opening it, trying something (short x with y, disconnect a from b etc.) put controller back together, install it into my bike again, test it, remove again etc.) Recently I bought a new controller which had a lot more output wires, and I was sure there was a way to disable the speed limit on this controller before I bought it, since there were so many wires and features etc.. Now I tested out everything and the most I managed to achieve from this controller was setting the speed limit to 23,5mph (38kmh) with the 3 speed function (I set it to 120%), but I'd love to have the speed limit completely gone, and have more freedom.
It's obvious that the speed is limited, because my motor always stops going further than 20mph / 23,5mph, even when I'm peddling as fast as possible (The more I'm peddling the less wattage is consumed by the motor. I have a wattmeter installed to monitor it constantly.) If anyone here knows or owns controllers rated at 48V 1000-1500W with an easy option to disable the speed limit completely, it'd be nice if I can get some recommendations and links. Thank you.

TL;DR: I'm searching for a good 48V 1000-1500W controller (with Hall Sensors) which has an option to disable the speed limit, or better, does not have a speed limit at all.

Greetings,
-Atdit

This here is the motor btw http://www.mxusebikekit.com/proshow.aspx?cateid=68&productsid=199


It is rated for 32kmh / 20mph... does that mean though that it can't go higher? The seller claimed 45kmh / 28mph.

There are a number of things that can limit speed, the motor itself has a limit that depends on the battery voltage. It is not going to be unlimited in any case.

Controllers often have programming that further limits the speed, but the fundamental limits are the system voltage and the motor windings. A fully charged battery will have slightly higher voltage and thus higher speed. The wheel size (and tire diameter) also affects the speed, as the motor limits are really in RPM per volt (also called Kv).

Without an RPM sensor somewhere, there cannot be a speed-limiting device. If your system will work without the RPM sensor working, then disable it and then use some other means to determine your speed. If there is no such sensor or if you've got it disabled and your speed is still limited, then there's something else limiting your system's speed, most likely maximum motor RPM, which has nothing at all to do with YOUR speed, rather the RPM of the motor. You might be up against a gearing issue - presuming this is a mid-drive (you didn't say).

RTIII said:

Without an RPM sensor somewhere, there cannot be a speed-limiting device.

Click to expand...

Multiphase motor controllers always have a way to know the RPM of the motor, and don't actually require a separate sensor for it.

The hall sensors in the motor in a sensored setup act as RPM sensors.

The phase feedback in a sensorless motor acts as RPM sensors.


However, when the controller is programmed to limit at a specific speed, that assumes the wheel (for a hubmotor) is a specific diameter. If the wheel is larger or smaller than that, then the RPM feedback isn't accurate, and it will limit speed incorrectly (too slow or too fast vs it's intended limit).





@OP: If the wheel can spin faster when off-ground (no load) than it does when riding it, then the speed limit is probably the voltage.

If the wheel spins at exactly the same speed either way, then the controller is probably limiting it.


If you have to mess around with testing various pad combinations in a controller, just go ahead and wire them all up, and run them all outside the case, with labels on each to match the pads. Then a notebook with all the pad labels, to mark down the results of each in. You can run them out to a busbar with screw termnals, and then just wire up pairs together as needed, or you can twist ends together, and tape off the ones you aren't testing, etc.

Still time consuming, but not nearly so much as having to open it up each time.

If you like you could even wire each pad up to SPDT switches, with the wire you're testing on the center lead and 5v on one of the outside leads, and ground on the ohter. Then you can switch functions while riding. (though you may have to power cycle the controller to reset it for the function).

Most likely, it's a simple setting in the controller. if you have an LCD, the setting is in there by pushing a few buttons. If your controller has the option of an LCD, but you didn't get one, then you need the LCD.

Show us a picture of your controller and all its connectors so that we can advise further.

Its quite possible that the motor is wound for low rpm, and with 48v the speed will max out at about 20 mph. And the seller thought it was wound faster.

The speed rating on that page is kind of meaningless, unless it states a rim size, and voltage. It should be something like 350 rpm @ 36v, or whatever. But since you have put another controller on it, and set it for fast as it goes, and only get 20 mph, I'm betting you have a low rpm motor.

On the other hand,, your speed is now spot on for 36v, and a normal speed motor. What exactly is your voltage? when riding?

One way to investigate what you actually have is to remove the motor covers, and one side of the motor may have markings on it. if it says 9x7, its a motor that should go 28 mph on 48v. But if it says 6x9 or 6x10, then its wound for 20 mph max.

If you are stuck with a 6x9, then it will be a good motor for lower speed bikes, like cargo bikes. You can replace just the motor with one wound faster.

The details of your controller are pretty important for diagnosing your speed problem, but first read what amberwolf wrote. What's the max speed is with the wheel in the air? That tells you whether you really have a speed limit. Then a link to your controller. Otherwise, you might already own what could be recommended.

Entirely possible the guy just weighs 300+ pounds. If the wheel does 40- 45 mph no load, the whole problem could be the load.

Or,, his battery might sag to close 42v under load, resulting in the same speed as if he had a 36v battery full charged.

If it won't go 30 mph no load, then I'm still betting on the motor winding.

Thanks for so many replies and advice!

I can't open the motor right now to check what it says in it, but I fear that it is a 6x9 motor. It is most likely a cargo motor. I could ride uphill with my friend on the cargo rack at around 13mph, which was pretty fast. I didn't even have much momentum.

I used the 3 speed function of my controller and set it to 120% and when I tested the motor in the air, it went a little bit faster (I could hear it) than at 100%. That explains why I got up to 23.5mph / 38kmh while riding on it, instead of the normal 20mph / 32 kmh I usually get. I thought there was still some kind of speed limit, and not just the voltage which limits the speed because the 3 speed function allowed me to go faster. Does anyone know how the 3 speed function can make the motor go faster?

Btw I'm using this controller here: https://www.aliexpress.com/item/Free-Shipping-48V-1000W-45Amax-BLDC-motor-controller-E-bike-brushless-speed-controller-compatible-for-sensor/497637202.html

And the motor is a direct drive rear hub motor, rated for 36-48V 1000W. MXUS XF40. I bought it cheap in an ebay kit without batteries for ~160$ without shipping. Pretty cheap.

Now that I know that the rpm per volt is the problem, what do you guys recommend? Should I get myself a 60V 1500W controller and overvolt the motor to max. 67.2V to get a higher top speed (also, what do you guys think will I reach with that method? About 25mph? And what if I use the 3 speed at 120%?) I read on another thread here that someone overvolted their 48V 1000W motor for 3 years at 60V and a higher wattage and it still works completely fine. The other method is to get another motor with a higher rpm per volt rating, and replace it with the current hub motor. I have no experience in replacing motors, though.

Greetings, and again, thanks for all the replies.

Edit: Btw, I don't weigh 300lbs I'm around 160lbs

The motor could safely run at probably at least a couple hundred volts, if you wanted to.

So if the motor's windings (kV, RPM/Volt) are limiting the speed, then higher voltage will fix that.

You can go to the http://ebikes.ca/simulator and try different windings of the same motor to see the differences between them using the same voltage pack, and to try different voltages with the same winding / motor.

They don't have your specific motor, but picking any of them that has multiple versions will still show you the principle, and help you pick the pack voltage you need to make the one you have go fast enough for you.

The wider MXUS (45H) is listed there but you have to pick SHOW ALL from the dropdown list first.

amberwolf said:

The motor could safely run at probably at least a couple hundred volts, if you wanted to.

So if the motor's windings (kV, RPM/Volt) are limiting the speed, then higher voltage will fix that.

You can go to the http://ebikes.ca/simulator and try different windings of the same motor to see the differences between them using the same voltage pack, and to try different voltages with the same winding / motor.

They don't have your specific motor, but picking any of them that has multiple versions will still show you the principle, and help you pick the pack voltage you need to make the one you have go fast enough for you.

The wider MXUS (45H) is listed there but you have to pick SHOW ALL from the dropdown list first.

Click to expand...

Thanks. But seriously, would the motor work at 72V/75.6V? That would be crazy. And what about the wattage?

Seriously, the motor would work fine at any voltage up to the point the insulation of the windings can't handle it (hundreds of volts).


As for wattage, that depends on your controller's current limits and the actual loading of the motor. Generally the watt ratings on motors are for continuous wattage, so as long as you don't exceed that for long periods they'll work fine. Many motors will work fine at even twice their rated wattage as long as they're at their full speed (not bogged down), with bursts of much higher than rated.

It's all about heat; as long as not much is generated, or you can get rid of it, you could run them at quite a lot of power. There's a thread "definitive testing of heating/cooling hubmotors" with lots of info on that sort of thing. Other threads, too, but I'd start there.


The simulator linked previously has stats below the chart that show overheating times for various levels of power and load as you move the load line around the chart.

The three-speed switch can make the motor run 120% speed (actually closer to 110%) by changing the timing.

I didn't figure out how to change the winding settings on the ebike simulator :?

I think a 72V 1500W controller would make my bike go fast enough anyway. Would this controller work?: http://m.ebay.com/itm/48-72V-1500W-Electric-Bicycle-E-bike-Scooter-Brushless-DC-Motor-Speed-Controller-/302066880207

Could I also use 48V or 60V, after using 72V?

I'd say that if your motor is indeed a 6x9 or other slow wind, the easiest fix for your problem would be that 48-72v controller. 72v will perk it right up. With that controller, you could run any voltage battery you like, from about 42v 12s, to 90v 22s. The motor will be most happy, (if its a 6x9) and most efficient on a bit less, 18-20 s. Or 65-72v. But if you really want speed, you need to get a 9x7, and just swap out the cores.

It's likely to be a 40 amps controller, despite the 1500w marking. 1500w is its continuous rating. So make sure your 72v battery can stand 40 amps before you buy that one.

I have one very similar to it on my dirt e bike. FWIW, you can get 30 mph from 1000w, so at 72v, youd have plenty of power with a 20 amps controller, 1500w max.

So depending on your battery, you might just look for a lower amps, but still 72v controller.

dogman dan said:

So depending on your battery, you might just look for a lower amps, but still 72v controller.

Click to expand...

I use LiPo batteries, 3x 6S 10Ah 10C in series

Atdit said:

dogman dan said:

So depending on your battery, you might just look for a lower amps, but still 72v controller.

Click to expand...

I use LiPo batteries, 3x 6S 10Ah 10C in series

Click to expand...

A 22V battery? No wonder you have having top speed issues . . .

A higher voltage will give you a higher motor base speed.

billvon said:

Atdit said:

I use LiPo batteries, 3x 6S 10Ah 10C in series

Click to expand...

A 22V battery? No wonder you have having top speed issues . . .

Click to expand...

3x 6S packs in series would be 6 x 4.2v (max) = 25.2v x 3 = 75.6v, rather than 22v.

Even if the average voltage of the individual 6s packs is 22v, that's still 66v for all three in series.

Why he's using a "72v" pack but looking for a 48v controller/system, I don't know.

amberwolf said:

billvon said:

Atdit said:

I use LiPo batteries, 3x 6S 10Ah 10C in series

Click to expand...

A 22V battery? No wonder you have having top speed issues . . .

Click to expand...

3x 6S packs in series would be 6 x 4.2v (max) = 25.2v x 3 = 75.6v, rather than 22v.

Even if the average voltage of the individual 6s packs is 22v, that's still 66v for all three in series.

Why he's using a "72v" pack but looking for a 48v controller/system, I don't know.

Click to expand...

I used 8x 3S 5.2Ah, twice 4 in series and then in paralell to get 44.4V. I ordered a few 6S 10Ah batteries on Hobbyking, 4 actually. I wanted to get a 12S 30Ah battery before I found out here that I need a higher voltage to get a better speed. I will use a 18S 15.2Ah battery for the 72V controller now. Top speed should be enough with a fully charged battery. If not, it sure will be with the 3 speed function set to 120%

Is this battery pack possible? (See picture)

It puts 3x 6S 10Ah LiPos in series and 6x 3S 5.2Ah LiPos in parallel. I think it won't, but what should I do with my 4x 6S 10Ah LiPos and 8x 3S 5.2Ah LiPos? How should I wire them up? Should I just do 2 seperate battery packs, 18S 10Ah and 18S 5.2Ah and use the 10Ah one first until it's empty and then the 5.2Ah one? Or should I wire them all up in 12S 30.4Ah and use 2 1500W DC-DC boost converters in parallel to get 72V?

I installed the controller and tested out my bike. Three Speed at 120% allowed me to get a top speed of 54kmh (without peddling ofc) with a fully charged 18S 5.2Ah battery. Thanks so much for telling me how to upgrade the top speed. I was so happy when I tested the wheel in the air and it was rotating so fast, it's like a lamborghini revving up for me. Beautiful. It uses about 1300-1400 Watts at full speed. (Controlled rated for 1500W)


The acceleration is stunning.
I love this new hobby