Under-voltage Warning (Lightning Bolt)
Raspberry Pi Single-Board Computer
Severity: ModerateWhat Does This Error Mean?
The lightning bolt icon (or yellow warning triangle) means the Pi is not getting enough voltage from its power supply. This causes instability, random crashes, and SD card corruption. Use the official Raspberry Pi power supply for your model.
Affected Models
- Raspberry Pi 5
- Raspberry Pi 4B
- Raspberry Pi 3B+
- Raspberry Pi Zero 2 W
- Raspberry Pi 400
Common Causes
- Power supply cannot deliver enough current for the Pi and its peripherals
- Using a phone charger instead of the official Pi power supply
- Thin or long USB cable causing voltage drop
- Too many USB devices drawing power from the Pi
- Extension cable or power strip adding resistance
How to Fix It
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Use the official Raspberry Pi power supply.
Pi 4: official 5.1V 3A USB-C supply. Pi 5: official 5.1V 5A USB-C supply. The extra 0.1V above 5V compensates for cable voltage drop.
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Use a short, thick USB-C cable.
Long or thin cables lose voltage over their length. The official Pi power supply has a built-in cable of the correct gauge.
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Remove power-hungry USB devices.
External hard drives, USB fans, and LED strips draw power from the Pi. Use a powered USB hub for devices that need significant current.
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Do not use a power strip or extension cable between the supply and the Pi.
Each connection adds resistance, which drops the voltage. Plug the power supply directly into the wall outlet.
Frequently Asked Questions
Can under-voltage damage my Raspberry Pi?
Under-voltage itself does not damage the Pi hardware. But it causes crashes that can corrupt the SD card, potentially losing data.
How do I check for under-voltage from the command line?
Run: vcgencmd get_throttled. A result of 0x0 means no issues. Any other value indicates throttling has occurred — check the Raspberry Pi documentation for the specific bit meanings.