How to (Re)build an Ebike Charger and Add a Fan to Keep It Cool

Hi guys. In the last article we saw how to make a Fiido D4S Battery removable, but now to charge it we will need a charger and we know that the Fiido one supplied in the summer overheats a little too much.

For this reason, in this article, we will open that charger and insert it together with a 12V power supply in a junction box along with a fan that will keep it cool and will ensure a better performance of the power supply.

Yes, you read that right! That's it. If the charger is at the right temperature (about the ambient temperature) it works better because the electrical components are sensitive to temperature (for example: the resistors change their resistance value with the temperature change).

Let's start then!

You can read this article also here

• Fiido original charger
• 12V power adaptor (for the fan)
• A 70mm PC fan
• A junction box (with the right dimensions)

First, you need to drill the holes on the junction box cover to let the fan take in fresh air from the outside and push it inwards to let the hot air out of the holes at the bottom.

Once you understand where is most convenient to mount the fan, from the inside you will have to attach with glue or double-sided tape a paper template that I made with Auto Cad to make the holes precisely with the drill and a 6 mm drill bit.

Once you have attached the template inside the lid you can proceed to drill the holes by placing the lid on a wooden base (which can be damaged) and making the holes.

After this step, you can place the fan from the inside and drill holes for the fan screws.

After making the holes on the lid, you need to make the holes on the junction box at the height of one centimeter spaced one centimeter from each other along the entire perimeter of the box

In this way, we will not only let fresh air into the interior but, thanks to the pressure that will be generated, the hot air that will be heated by the components will also come out through these outlet holes.

In this way we have, when the box is closed, a complete exchange of air that lets in fresh air from above and lets out hot air from the holes at the bottom.

After making the holes and ensuring the right airflow, it's time to make the electrical connections

Who among you has ever used the AC connector by unplugging and reattaching it every time? Nobody, I knew!

For this reason I unsoldered it with tin and the soldering iron so I recovered some space inside. After doing this, I took the cable and cut the connector to it and re-soldered the two wires of the cable where the connector used to be.

Next to these two wires I soldered in parallel the other two wires that power the 12V power supply for the fan (wires that I cut to size)

Finally, I connected the wires (of the 12 volts) to the fan

If you were wondering why I didn't connect the fan to the bike power supply via a step-down module, the answer is that all the step-down modules accept a maximum voltage of 36 volts in input while the bike charger supplies a voltage of 42 volts.

However, even if it could have been done, I preferred to keep the two circuits disconnected because the fan would constitute a load and "steal" current from the charging process of the bike.

p.s. to pass the cables I made two grooves on the walls of the box

Done! You now have your brand new power supply for e-bike which is also cooled. I hope I have helped you if you were looking for a solution to this problem.