Choice of the controller

[Jay-Cee]

Hello everyone,

I own a Fiido T1 Pro cargo fatbike, weighing 37kg, equipped with a 750W motor and a 48V 25A controller with 12 MOSFETs. Due to a degradation of my controller, I replaced it with a generic model of unknown brand (48V 25A, "SQUARE wave" type, 9 MOSFETs) purchased on Aliexpress: https://fr.aliexpress.com/item/1005004870053287.html.

However, during trips of about 10 km in the city on flat roads, without stopping, at a maximum speed of 28-30 km/h and without carrying any load, this new controller overheats and stops. I want to replace it with a Kunteng model (48V 25A, "SINE wave" type, 9 MOSFETs) available here: https://fr.aliexpress.com/item/1005004045976054.html.

Do you think there will be a significant difference in terms of performance and endurance? Or is it better to buy the original controller which has 12 MOSFETs?

Thank you for your advice.

 

[saneagle]

You need at least 12 MOSFETs for that type of punishment.

When it says 25A, that means the maximum current it will give. It's only rated at half that, so if you draw more than 12.5A for any period of time, the temperature will rise continuously until it overheats.

Only you know what sort of riding you're doing and how much current you're using. Look at your LCD to get your modal watts, divide it by the battery voltage to get the amps, then double it to get the maximum current controller needed. For example, if your modal watts is 1000w and you have a 48v battery, that's 20 amps, so you need a 40A controller.

 

[Jay-Cee]

You need at least 12 MOSFETs for that type of punishment.

When it says 25A, that means the maximum current it will give. It's only rated at half that, so if you draw more than 12.5A for any period of time, the temperature will rise continuously until it overheats.

Only you know what sort of riding you're doing and how much current you're using. Look at your LCD to get your modal watts, divide it by the battery voltage to get the amps, then double it to get the maximum current controller needed. For example, if your modal watts is 1000w and you have a 48v battery, that's 20 amps, so you need a 40A controller.

Alright, I understand. Thank you!

My original controller is 48V and 25A, but it has 12 MOSFETs. Is it thanks to these 3 additional MOSFETs that it never stopped, even when I was riding at a higher speed?

When the motor demanded the most power, the screen displayed 999W and did not exceed this figure, as if it was locked at that value. According to your calculation method, I would need a 40A controller, but after quickly examining the available options on the market, I see that there are models of 30A, 35A, and then it jumps directly to 50A. I would be more inclined to opt for a 35A sine wave controller to minimize noise. Can you recommend some good quality controller brands without spending a fortune? Is it possible to mention Kunteng among these brands?

 

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ppl use them instead of mid drive bafang hd motors standard ones for 3x the amps but the batt must be capable of feeding it or it will explode

 

[saneagle]

Alright, I understand. Thank you!

My original controller is 48V and 25A, but it has 12 MOSFETs. Is it thanks to these 3 additional MOSFETs that it never stopped, even when I was riding at a higher speed?

When the motor demanded the most power, the screen displayed 999W and did not exceed this figure, as if it was locked at that value. According to your calculation method, I would need a 40A controller, but after quickly examining the available options on the market, I see that there are models of 30A, 35A, and then it jumps directly to 50A. I would be more inclined to opt for a 35A sine wave controller to minimize noise. Can you recommend some good quality controller brands without spending a fortune? Is it possible to mention Kunteng among these brands?

Just checking that you understand what modal current is.

 

[Jay-Cee]

Just checking that you understand what modal current is.

I didn't manage to understand (despite the translation) what you wrote to me

 

[saneagle]

I didn't manage to understand (despite the translation) what you wrote to me

Modal current is the amount of current you use the most when you're riding your bike.

You only get maximum current at low speed.

 

[Jay-Cee]

Modal current is the amount of current you use the most when you're riding your bike.

You only get maximum current at low speed.

I think I understand what you're telling me, but I'm not sure.

In any case, by calculating my power needs during the most energy-intensive periods (acceleration and/or on hilly terrain), I get the following result : 999W / 48V = 20.83A * 2 ≈ 40A. According to this calculation, I should opt for a 40A controller, which would provide the necessary power without overloading the system, thereby reducing the risk of overheating.

However, I haven't been able to find a 40A Kunteng sine wave controller on AliExpress. Therefore, I'm considering acquiring a 35A controller. Although it is slightly below my ideal need, it still has 12 MOSFETs, which might be sufficient for my requirements. What do you think?

 

[saneagle]

I think I understand what you're telling me, but I'm not sure.

In any case, by calculating my power needs during the most energy-intensive periods (acceleration and/or on hilly terrain), I get the following result : 999W / 48V = 20.83A * 2 ≈ 40A. According to this calculation, I should opt for a 40A controller, which would provide the necessary power without overloading the system, thereby reducing the risk of overheating.

However, I haven't been able to find a 40A Kunteng sine wave controller on AliExpress. Therefore, I'm considering acquiring a 35A controller. Although it is slightly below my ideal need, it still has 12 MOSFETs, which might be sufficient for my requirements. What do you think?

It'll be fine.

 

[Jay-Cee]

It'll be fine.

Thank you! The controller has been ordered, and I can't wait to see it in operation.

I have a question regarding my headlight (with two lighting intensities) and my horn, which are connected to my switch. How can I identify the wires without the switch being powered? The switch has a 5-wire cable. I plan to use the continuity test, but how can I identify the wires that deliver 48V and the ground? The idea is to extend the switch cable (which is already connected to the headlight and horn) to the battery to create this parallel lighting circuit.