Testing and teardown of a 120W fast-charge adapter bought for 2.6 yuan on Douyin Mall.
The seller claims it’s “for Huawei” and the shell is a knock-off of Huawei’s design.
Let’s crack one open and see what a few-yuan charger is actually made of.
Test & teardown video: https://www.bilibili.com/video/BV1kf42127Cu/
UNI-T / Tolia bench PSU X08P3010 unboxing, review & teardown: https://blog.zeruns.com/archives/698.html
Riden RD6012P CNC bench supply quick unboxing & review – 60 V 12 A DC, switching + linear post-reg: https://blog.zeruns.com/archives/740.html
Genuine Huawei 100 W charger purchase link: https://u.jd.com/9sxOBRm
Appearance
Only one USB-A port, labeled “120w Fast Charge” underneath.
Text printed on the bottom:
- Model: 120W
- Input: 180-240 V ~ 1.8 A 50/60 Hz
- Output: 5 V/9 V/12 V/15 V=3 A, 20 V=3.3 A
Manufacturer: Shenzhen Weitemei Trading Co., Ltd.
Weight: 53.5 g.
Testing
Quick-check of supported protocols – quite a few, but max voltage stops at 12 V; the advertised 20 V never appears.
Real-world max: 12 V, 15.6 W. Under full load the voltage collapses to 9 V; efficiency ≈ 80 %.
Output ripple at 12 V 1 A: ~460 mV pp – rather high.
5 V no-load ripple ≈ 100 mV pp.
Teardown
Pop the top cover.
Pull the board – a lump of iron acts as ballast on the transformer. Classic fly-back.
Remove the weight.
Bottom side of PCB.
Side view: primary filter cap 400 V 6.8 µF (undersized), Y-cap 2.2 nF.
Output cap blocked by the USB shell – only 16 V rating visible; measured 644 µF.
Inrush-limiting carbon-film resistor before the bridge.
Bridge rectifier MB10F – 1000 V / 1 A.
Primary-side IC: FAB3B09A – no datasheet.
Pin 2 senses current through a 1 Ω resistor; shaving that value would raise power – and danger.
Output switch: QC7801 / FAE41150 – also unidentifiable, likely a MOSFET.
Opto-coupler: PC817C.
6-pin protocol chip beside the USB port: 118 / 352DEA – no info anywhere.
Bottom line: don’t buy these. Parts are rock-bottom cheap and performance is wildly overrated.
Further reading
- Budget & high-value VPS / cloud server picks: https://blog.zeruns.com/archives/383.html
- Minecraft server setup guide: https://blog.zeruns.com/tag/mc/
- Zero-code personal blog building tutorial: https://blog.zeruns.com/archives/783.html
- Build your own NPS intranet-penetration server: https://blog.zeruns.com/archives/741.html
- Deploy Stable Diffusion on Rain-Cloud GPU servers – roll your own AI art site: https://blog.zeruns.com/archives/768.html
- Open-source smart electronic load based on CH32V307 – embedded contest project: https://blog.zeruns.com/archives/785.html