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**Ok forgive my use of some terms and clustered explanation

I have this 5inch(13cm) DC rechargeable fan, made by lontor(some company in china but popular in Nigeria) that's rated (i.e written on the box and the fan itself) "Max power input=4W" and "Voltage=5V". The USB port broke off recently and I've come up with an idea of creating an external battery voltage source. Connecting battery and co. isn't the issue here.

I checked AliExpress and found different PWM speed controllers for DC motors but I'm still trying to figure out the maximum voltage this fan can operate at and also the maximum current. A friend gave me an idea of connecting the battery directly to the motor but that would only be 3.7 volts and that's too small (or so I think). Hence, in the images attached, you will find the picture of the PCB that's inside the fan. From my understanding, it controls not only the charging of the 18650 battery, but it also controls the speed of the fan (note, it's a 3 speed fan...like 3 clicks increasing the speed 1 - 2 - 3 then final click switches it off).

I'm hoping that from the picture of the pcb, you can help me determine the max current (but voltage most importantly). Also, There's DC to DC charge controller on AliExpress that will charge the batteries but also boost the output voltage to 5V. Will that 5v be too much for the motor on its own? Or does it need regulation?

Thank you so much for the help and ask questions if you don't understand any part of this! Find below the top and bottom views of the PCB respectively Bottom view of PCBTop view of PCB

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  • \$\begingroup\$ Why not just use the same board the fan originally had and feed it a regulated 5V from your battery? That's what you're doing anyway if you power it from a USB battery bank. You'd just be bypassing the USB connectors. \$\endgroup\$
    – Hearth
    Jun 17, 2021 at 14:34
  • \$\begingroup\$ The contact points for the USB input port was destroyed (The bottom left corner of the 2nd picture ) \$\endgroup\$
    – Sam
    Jun 17, 2021 at 14:39
  • \$\begingroup\$ I can promise you there are other 5V and ground contacts on that board, you just need to find them and solder to those instead. \$\endgroup\$
    – Hearth
    Jun 17, 2021 at 14:40
  • \$\begingroup\$ Alright I'll do that. Thank you 😊 \$\endgroup\$
    – Sam
    Jun 17, 2021 at 14:57

1 Answer 1

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I am not sure I get your question. So, here are some points that would help if clarified.

  1. It is a rechargeable fan, so, has a battery. If only the usb port broke, you can easily attach another one. It is not expensive or rare.
  2. Where do you want to put the new battery?
  3. Figuring out the circuit diagram from PCB picture is not very easy.It would help more if you could just give the fan's model no.

You should check the motor's body. There should be some information on it. Assuming that the motor itself is 5V-4W, its maximum current would be 800mA. if you don't need the speed control then sure you can connect the battery directly to the motor. In that case, you will have to use two batteries, one 3.7V and one 1.5V, in series.

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  • \$\begingroup\$ 1. The USB port was destroyed but someone commented that I can also trace it somewhere else from the board. 2. This isn't really an issue but a separate container (a small one that is but I'd use wires to connect it to the fan). 3. The fan's model number is Lontor CTL-MF013-4 but there's also a model numbrr on the PCB (KM-692-01) \$\endgroup\$
    – Sam
    Jun 17, 2021 at 14:54

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