250 watt motor and 18max current controller?

[Electricmover]

I have a 250 watt nominal front hub motor. I have a 48 volt battery and the controller that seems to work best with the wires is a 18max current controller that I have. Would this work or would it fry the motor in a winter barbecue?

I am thinking short bursts it could probably be fine now in winter right? If careful it won't fry, if gearing down in up-slopes ? Or is this a stupid idea. Maybe I should lower to max current controller of 15a?

Motor and controller is in these images.

 

[RunForTheHills]

Chances are it will be fine. The motor is rated for 250 watt continuous, but should be able to burst higher for short periods. If it has a temperature sensor and the controller supports that feature, it will shutdown the motor before it overheats on a long climb.

 

[PCeBiker]

That sounds like a bit too much power to me?

A fully charged 48V battery is 54.6V
That's almost 1000 watts at 18 amps.

Your display settings may allow you to turn down the maximum power.
Otherwise be real careful giving it over 900 watts.

Temperature sensors in motors are very rare, and a motor can overheat and burn out in less than a minute.

Just be really careful and keep putting your hand on the motor to see how hot it is.
Your first test ride is the most important.
Check the motor temperature every couple of minutes at first to see what it takes to get it hot.

 

[Electricmover]

That sounds like a bit too much power to me?

A fully charged 48V battery is 54.6V
That's almost 1000 watts at 18 amps.

Your display settings may allow you to turn down the maximum power.
Otherwise be real careful giving it over 900 watts.

Temperature sensors in motors are very rare, and a motor can overheat and burn out in less than a minute.

Just be really careful and keep putting your hand on the motor to see how hot it is.
Your first test ride is the most important.
Check the motor temperature every couple of minutes at first to see what it takes to get it hot.

I have a kt-lcd3 and a sw900 lying around. Anyone knows if one of them supports this feature of turning down the max current?

 

[PCeBiker]

I have a kt-lcd3 and a sw900 lying around. Anyone knows if one of them supports this feature of turning down the max current?

Your kt-lcd3 allows you to adjust your maximum power,..

Here's a link to the owners manual.
(The display will show you the motor temperature, but you normally have to install the temperature sensor in the motor yourself)

https://www.ebikes-canada.com/Displays/KT-LCD3.pdf

As a general reference, motors can usually handle double their rated power continuously without overheating, so 500 watts at 36 volts is ~13.9 amps, and 500 watts at 48 volts is ~10 amps.

If it were me, I'd cut the power in half (C5=3 9amps) and see how it goes.
If it's too gutless, turn the power up a notch and try it again.

I didn't want to worry about cooking my motor, so I cut my power in half so I could ride full throttle without worrying about it.

 

[RunForTheHills]

Grin sells that motor, and at least their version comes with a thermister. They do warn that allowing too much phase current can strip the gears. https://ebikes.ca/product-info/grin-kits/bafang-g310-g311.html

 

[PCeBiker]

Grin sells that motor, and at least their version comes with a thermister. They do warn that allowing too much phase current can strip the gears. https://ebikes.ca/product-info/grin-kits/bafang-g310-g311.html

Yeah Grin sells good stuff but you'll need the Cycle Analyst to go with their motor to read the motor temperature data.

As far as I know, to use the "Motor Temperature" readout on the KT display, you not only need a temperature sensor in your motor, you also need to wire it all the way up and into the display and solder the wires directly on to the circuit board inside.

The KT wiring harness doesn't have the extra wire for the motor temperature sensor, so it has to be completely installed separately.

@Electricmover that Grin link is great!!
They show you all the ways that the motor can fail.

Knowing how it can out, helps you to know how to run it hard without it breaking or ing up.

 

[RunForTheHills]

It looks like Grin sells parts for the motor if you do manage to strip the gears: https://ebikes.ca/shop/electric-bicycle-parts/motor-hardware/g311gear.html

 

[harryS]

I run a 25A KT sinewave controller with a 48V battery into this little Q100H 250W motor. It's rider restraint that keeps it from melting. I use it with an LCD3 display. It might show 1200 W briefly on a hill, but it would be foolish run it at high levels sustained . That's 25A peak anyway. KT expects you to run it at 12 A which is 500-600W,


By the way, displays are specific to the controller brand, I doubt an LCD3 or SW900 work with the controller in your picture. I have turned down the current in KT displays to allow the bike to run around 100-120 watts in level 1. That's so I can go slower and not out run my wife in PAS 1.

 

[PCeBiker]

By the way, displays are specific to the controller brand,

Ooops, I missed that.

Temperature sensors in motors are very rare, and a motor can overheat and burn out in less than a minute.

I put a "Temperature Sensor" on my motor.

https://a.aliexpress.com/_mNlhD4D

It can help you keep an eye on the motor, but it's not any better than just reaching in and touching the motor to check it.

 

[Electricmover]

Ooops, I missed that.




I put a "Temperature Sensor" on my motor.

View attachment 204123

https://a.aliexpress.com/_mNlhD4D

It can help you keep an eye on the motor, but it's not any better than just reaching in and touching the motor to check it.

You just basically paste that thing onto the motor? To check temp.

 

[Electricmover]

So I have made it move now at least. With an external throttle. Had to clip of the cables there a bit to get it onto the controller. It is not generic throttle to jhrak so different interface/hookup there at the cables.

Anyway, now it is moving. I am pressing full throttle all the time in the video so no interruptions with lighter press from the thumb. But kind of sounds a bit "weird". Like with "bursts". Any idea if this sounds normal or if the sound should be exactly the same at full throttle all the time? Not with bursts like this?

ow's Video - Jan 1, 2026

www.veed.io

See vid.

 

[PCeBiker]

You just basically paste that thing onto the motor? To check temp.

Yeah, its a sticker.
Like the kind for an aquarium, but it's for a coffee kettle so it reads temperatures that would cook regular lol

 

[RunForTheHills]

So I have made it move now at least. With an external throttle. Had to clip of the cables there a bit to get it onto the controller. It is not generic throttle to jhrak so different interface/hookup there at the cables.

Anyway, now it is moving. I am pressing full throttle all the time in the video so no interruptions with lighter press from the thumb. But kind of sounds a bit "weird". Like with "bursts". Any idea if this sounds normal or if the sound should be exactly the same at full throttle all the time? Not with bursts like this?

ow's Video - Jan 1, 2026

www.veed.io

See vid.

Phase wires / hall sensors are not in the right order. You have to try different combos until you get it right. Don't do it at full throttle.

 

[PCeBiker]

Phase wires / hall sensors are not in the right order.

The three Fat Phase wires are color matched and paired with the same color hal sensor wire, so when you swap a Phase wire you swap the same color hal sensor wire along with it.

The guy in the video didn't do that and had to do a lot of trial and error.
You can damage your hal sensors if they aren't paired properly.

There's four hal sensors in my motor.
Three Phase monitors, and a Speed magnet monitor.

 

[RunForTheHills]

The three Fat Phase wires are color matched and paired with the same color hal sensor wire, so when you swap a Phase wire you swap the same color hal sensor wire along with it.

The guy in the video didn't do that and had to do a lot of trial and error.
You can damage your hal sensors if they aren't paired properly.

I'll be honest, I didn't actually watch the video. I just grabbed the first one that looked like it covered the subject. At any rate, it isn't rocket science.

 

[RunForTheHills]

Maybe this link will work better, although he does test the order of the phase wires and hall sensors separately. https://letrigo.com/blogs/knowledge...Qdxzz6dWEuSdJLBru7kqcMHSWeS8uHTu4-2F7DMjjJXBj

 

[PCeBiker]

See vid.

If that were my motor, I'd take it apart and grease it, especially if I was planning on super-charging it.

Wipe off the clumps so they don't get flung off into were they shouldn't go,..

 

[PCeBiker]

Maybe this link will work better, although he does test the order of the phase wires and hall sensors separately.

Yeah, that might be necessary for proprietary equipment.

They do s*it like mismatched wire colors to sell you their own replacement parts.