FAQ
TL;DR: Xiaomi 20000 mAh not charging? A 3 A module can cut time by ~50%; "charging time should be reduced by half." Check the micro‑USB pads and measure pack voltage before/after plugging in. [Elektroda, E8600, post #17315378]
Why it matters: This FAQ helps Xiaomi 20000 mAh owners fix no‑charge, blinking‑LED, or ~3.3 V issues and decide between DIY repair, module bypass, or replacement.
Quick Facts
- Only micro‑USB pins 1 (VBUS) and 5 (GND) are required for charging; data pins are not. [Elektroda, E8600, post #17314298]
- TP4056 charger modules provide about 1 A; simple fallback but slower. [Elektroda, E8600, post #17314863]
- A 3 A charger board plus a strong 5 V supply can halve charge time versus 1.5 A. [Elektroda, E8600, post #17315378]
- Cheap multi‑cell housings often parallel cells without a balancer—don’t mix unmatched cells. [Elektroda, Frog_Qmak, post #17314896]
- You can replace a broken micro‑USB socket using a regular iron, good flux, and a flat tip. [Elektroda, E8600, post #17311686]
Why won’t my Xiaomi 20000 mAh power bank charge even though LEDs cycle?
Start by cleaning the micro‑USB socket with isopropyl alcohol. Then measure the pack voltage while you plug in the charger. If the voltage does not rise, the input path is open or the jack is faulty. This quick test differentiates a dead input from a weak cell issue. Next, inspect the connector legs and anchor tabs under magnification. Replace or re‑solder the socket if legs or pads are cracked. [Elektroda, E8600, post #17309434]
My meter shows about 3.292 V across +/−. What does that tell me?
A reading around 3.29 V that doesn’t increase when you connect the charger indicates the charging path isn’t delivering power. In the thread, the voltage stayed ~3.292 V when plugged in and crept only to ~3.324 V after many hours. That pattern points to a damaged micro‑USB connector or lifted pads. Inspect the jack under a microscope for broken legs or missing pads. [Elektroda, cross099, post #17311882]
How do I confirm the micro‑USB jack is the culprit?
Check which micro‑USB pins still connect to the board. Only pins 1 (VBUS) and 5 (GND) are required for charging. If either is lifted or its pad is gone, the power bank won’t accept charge. Re‑solder those pins or replace the connector and retest. "For charging you need pins 1 and 5." [Elektroda, E8600, post #17314298]
Can I re‑solder the micro‑USB port without hot air?
Yes. Use a standard soldering iron, quality flux, and a flat tip to bridge the pin row efficiently. Clean old solder, align the jack, tack the shell tabs, then drag‑solder the pins with flux. Finish by inspecting for bridges under magnification. "I recommend a flat tip to heat all pins at once." [Elektroda, E8600, post #17311686]
What iron temperature and technique help avoid PCB damage?
Use a moderate iron temperature and short contact time. Pre‑tin the pads and pins, apply gel flux, and let the solder flow quickly. Secure the shell tabs first to avoid pad stress, then solder the signal pins. Clean residues with isopropyl alcohol and re‑inspect. Practice on scrap boards if you’re new to connector work. [Adafruit, 2022]
Two connector pads ripped off. Is the board still repairable?
Yes. With the right skills, the board is salvageable. A careful technician can rework the area and restore connectivity. If you lack experience with pad repairs, consider professional help to avoid further damage. "The board is salvageable but for a good soldering iron operator." [Elektroda, E8600, post #17314863]
Do I need D+ and D− pads to charge this power bank?
No. The power path uses only micro‑USB pin 1 (VBUS) and pin 5 (GND). Missing data pads usually won’t stop charging, though they can affect fast‑charge negotiation on some devices. "For charging you need pins 1 and 5." [Elektroda, E8600, post #17314298]
How do I quickly diagnose the charging path?
Try this: 1) Clean the micro‑USB socket thoroughly. 2) Measure pack voltage, then plug in the charger and watch for a rise. 3) If voltage doesn’t increase, focus on the connector, pads, and input traces. This method confirms whether the charger’s voltage reaches the battery. [Elektroda, E8600, post #17309434]
Can I use a TP4056 module to charge the cells directly?
Yes, but only for a single 1‑series pack (cells in parallel). TP4056 is a 1 A linear Li‑ion charger designed for 1‑cell applications. It’s slower but simple. Do not use TP4056 on multi‑series packs without a proper multi‑cell BMS/charger. Confirm cell configuration before wiring. [TP4056 Datasheet]
How can I charge faster than with a 1.5 A input?
Use a charger board that supports up to 3 A and pair it with a capable 5 V supply. Expect roughly half the charge time versus 1.5 A, assuming the power bank’s controller accepts the higher current. "Charging time should be reduced by half." Note: some boards omit a micro‑USB port and use thermistor inputs. [Elektroda, E8600, post #17315378]
Are cheap 6–8 cell power‑bank housings reliable and safe?
Quality varies. Many budget housings wire cells in parallel without a balancer, so you should not mix cells of different ages or histories. That mismatch can reduce capacity and stress cells. "Do they work well – hard to tell. Probably depends on the model." [Elektroda, Frog_Qmak, post #17314896]
Is a 60–70 PLN port repair worth it versus buying new?
It depends on your skills and time. Shops quoted 60–70 PLN for repair, while a new power bank costs ~120–130 PLN. A DIY fix with flux and a standard iron can be far cheaper if you’re comfortable with connector work. Otherwise, replacement may be more economical. [Elektroda, cross099, post #17311679]
Why did charging take over 14 hours at 1.5 A?
Large capacity plus conversion losses can stretch charge times. In the thread, the unit “landed on the 1500 mA charger over 14 h.” Higher input current reduces time only if the controller and cabling allow it. Consider a 3 A‑capable board and supply to shorten sessions. [Elektroda, cross099, post #17314898]
What power supply do I need for a 3 A charger board?
Use a robust 5 V USB supply rated at 3 A or higher. Lower‑rated adapters will current‑limit or sag, extending charge time. Some 3 A boards lack a micro‑USB jack and may include a thermistor header; plan wiring accordingly. Verify cable quality to minimize voltage drop. [Elektroda, E8600, post #17315378]
