It’s obviously an AI-generated image, but it still managed to shock me at first glance. I wasn’t expecting to see something like that.
coords: 50.134337813934366, -5.7046192668621245
I built a simple DIY power bank circuit using these components:
1× 18650 Li-ion battery (3.7 V nominal, 2500 mAh) TP4056 charging module MT3608 boost converter module adjusted to 5 V output USB-A female connector for the output
I also connected the TP4056 input to a solar panel that can generate up to 7 V. The solar charging seems to work normally, but I’m mentioning it in case it affects the issue.
After assembling the circuit, I adjusted the MT3608 output to 5 V and connected my smartphone to the USB output as a test (probably not the safest device to test with, but I did it anyway).
While testing, I monitored the output voltage with a multimeter and observed this behavior:
When I plugged in the phone, the output voltage immediately dropped from 5.0 V to around 4.8 V. The phone started charging. About 1 second later, the voltage dropped further to around 4.3–4.4 V, and the phone stopped charging. Another second later, the voltage recovered to about 4.8 V, and charging resumed.
This cycle repeated continuously as long as the phone remained connected.
The battery initially arrived at about 3.6 V. I charged it up to approximately 4.1 V and repeated the test, but the behavior stayed the same.
For wiring, I used generic jumper wires (estimated around 24 AWG).
What could be causing this issue?
EDIT: I noticed an error in the diagram I attached. The MT3608 boost converter connections are labeled incorrectly. VIN and VOUT are swapped in the diagram. The actual physical circuit is wired correctly; only the diagram is wrong. Please ignore the MT3608 labeling mistake and assume the real connections are correct when diagnosing the issue.