Ep. 5 | Tearing down a ¥20 Pinduoduo brushless folding mini fan — incredible value

¥19.38 Pinduoduo FC-6638D folding mini fan teardown: confirmed 1503 brushless motor, 5-blade prop, 10 speeds on an LED display, about 50g thrust; unmarked cells in parallel with no BMS, so an AWithZ welder swaps in two high-capacity cells + a BMS for 5000mAh

A follower recommended a so-called brushless “monster” mini fan, ¥19.38 paid (model FC-6638D, rated 1800mAh, 91×35×191mm, Type-C charging, folding). Features: about 10 speeds, a small LED digit display, plenty of airflow — about 50 grams of thrust on top speed, folds for carrying. Opened up: the main connections use plugs, easy to repair; lots of motor wires, confirmed brushless, the motor should be a 1503, 5-blade prop. The cells are dreadful: no capacity rating, no markings at all, negatives joined so they’re in parallel, and the unit has no BMS. Since it’s open anyway, he swaps in two high-capacity cells and adds a BMS against over-charge and over-discharge; welding with the AWithZ welder is handy, and it’s bumped straight to 5000mAh — over twice the original. Verdict: excellent value for ¥20, he suspects the seller is running a charity; a controller board alone for a home-built 1S brushless fan costs ¥20-plus online. 1368 comments: many say later batches cut corners and only have one cell, and the price went up; someone at the same shop plans to fit 2 EVE 33V cells; someone shows a fan with 800-plus grams of thrust.

Outcome

Steps6 steps · click a frame to jump

1. 
   1. Purchase and specs

   A brushless fan a follower recommended, ¥19.38 paid (¥3.42 off); FC-6638D, 1800mAh, 91×35×191mm; folding, Type-C charging.

   00:03 – 00:31
2. 
   2. Features: 10 speeds, LED display, about 50g thrust

   About 10 speeds, a small LED digit display, plenty of airflow; about 50 grams of thrust on top speed; folds for going out; whether it’s brushless — open it and see.

   00:31 – 01:12
3. 
   3. Teardown: plug connections; 1503 brushless motor, 5-blade prop

   The main connections use plugs, easy to swap and repair; lots of motor wires, brushless confirmed; the motor should be a 1503; 5-blade prop.

   01:18 – 01:47
4. 
   4. Dreadful cells, no BMS → swap the cells and add a BMS

   The cells have no capacity rating and no markings; negatives joined, so parallel; the unit has no BMS, so add one against over-charge and over-discharge; swap in two high-capacity cells.

   01:47 – 02:17
5. 
   5. Weld with the AWithZ welder, bump to 5000mAh

   Welding with the AWithZ welder feels pretty handy; bumped straight to 5000mAh, over twice the original.

   02:26 – 02:40
6. 
   6. Verdict: great value — a home-built controller alone costs ¥20-plus

   The ¥20 mini fan is great value, he suspects the seller is running a charity; a controller board alone for a home-built 1S brushless fan costs ¥20-plus; that’s the teardown and mod.

   02:40 – 03:07

Bill of materials

Measured on camera

Creator’s tips

• Negatives joined means the cells are in parallel, so you can swap straight to bigger cells in parallel 01:55
• Cheap fans usually have no BMS — always add one when modding 02:09
• Plug connections make swaps and repairs easy 01:18

Pitfalls

• Original cells unmarked, no BMS 01:55
• Comments: later batches cut corners, only one cell left, and the price went up

Li-ion safety

• Li-ion without a BMS risks over-charge and over-discharge; add one when modding 02:09

Quotes

Cost & time