I bought a brand new Raspberry Pi 3B+ the other day. I went to power it up and I immediately noticed a yellow lightning bolt in the upper right hand corner of the screen. After a little research I discovered what that meant.
What does the lightning bolt mean on a Raspberry Pi? The yellow lightning bolt symbol indicates that the Raspberry Pi is not receiving enough power. Be sure to use the appropriate power supply for your Raspberry Pi model.
So now that we know what the lightning bolt means, we still need to know how much power your Raspberry Pi needs.
Raspberry Pi Power Requirements
As Adafruit releases more powerful versions of the Raspberry Pi, the power requirements tend to increase. Below you can find a table with the requirements for each model.
|Product||Recommended PSU current capacity||Maximum total USB peripheral current draw||Typical bare-board active current consumption|
|Raspberry Pi Model A||700mA||500mA||200mA|
|Raspberry Pi Model B||1.2A||500mA||500mA|
|Raspberry Pi Model A+||700mA||500mA||180mA|
|Raspberry Pi Model B+||1.8A||600mA/1.2A (switchable)||330mA|
|Raspberry Pi 2 Model B||1.8A||600mA/1.2A (switchable)||350mA|
|Raspberry Pi 3 Model B||2.5A||1.2A||400mA|
|Raspberry Pi 3 Model A+||2.5A||Limited by PSU, board, and connector ratings only.||350mA|
|Raspberry Pi 3 Model B+||2.5A||1.2A||500mA|
|Raspberry Pi 4 Model B||3.0A||1.2A||600mA|
|Raspberry Pi Zero W/WH||1.2A||Limited by PSU, board, and connector ratings only.||150mA|
|Raspberry Pi Zero||1.2A||Limited by PSU, board, and connector ratings only||100mA|
As you can see, there is a sizable difference in power requirements between Raspberry Pi models. The Raspberry Pi Zero only requires 1.2A while the 4B requires 3.0. That’s a 250% difference!
It should also be noted that each Raspberry Pi is designed for a 5V input. There are two ways to connect power to your Raspberry Pi, either through a power supply port which is either a micro USB or a USB-C, and directly through the header pins.
How To Turn The Lightning Bolt Off
There are two ways to get rid of the lightning bolt from your screen. The first and best way is to replace your power supply with one that meets the requirements of your project. The second is not advised, but it is possible to disable the warning and prevent it from showing. To do this, follow the instructions below.
- Open /boot/config.txt
sudo nano /boot/config.txt
- Add this text to the bottom of the file
Disable under-voltage warning
- Reboot the Raspberry Pi to apply the change
Once you have completed these steps, you should no longer see the low voltage warning symbol. Again, this is not recommended as you will no longer be able to tell if your Pi is receiving enough power but the option is there for specific use cases.
Other Raspberry Pi Warning Symbols
While the lightning bolt is probably the most common error symbol seen by Raspberry Pi users, there are actually 2 other warning symbols that might show up as well.
Over Temperature Warning (80-85C)
This symbol will show up if your Raspberry Pi exceeds 80C (176°F). When this happens, your Raspberry Pi will start to slow down its processor in order to prevent any damage from occurring. If you are seeing this error often, consider taking some measures to cool off your Raspberry Pi.
Over Temperature Warning (Over 85C)
This symbol looks very similar to the previous one. The only difference is how full the thermometer is. If the thermometer is half full, then your board is between 80C and 85C. If the thermometer is completely full, then the temperature has gone over 85C.
At this point, your Raspberry Pi is starting to get into a dangerous place. It will throttle both the processor and the GPU in order to reduce the amount of heat it is producing. If you are seeing this on a regular basis, you will definitely need to add some type of cooling countermeasures to your Raspberry Pi.
Can you use a phone charger for a Raspberry Pi?
The short answer: it depends. Phone chargers provide a variety of voltages and amperages depending on the make and model of the phone that they were designed for. You will need to make sure that the charger is providing 5V and at least the right current to power your Pi.
If both of these requirements are met, you will still need to be careful as phone chargers tend to have higher power fluctuations than a standard power supply and tend to not be as closely regulated. If you are using a phone charger and you start to see the lightning bolt on your screen, your charger may not be stable enough to use consistently as a power supply.
Can you power a Raspberry Pi with a power bank?
Yes. Most USB power banks output 5V and can handle the amperage requirements for a Raspberry Pi. They also tend to be more stable than a standard phone charger. You will need to be careful and look at the total capacity of the power bank to determine how long your battery will last.
Some power banks may give you trouble because they shut off if not enough power is being drawn from them and many are unable to both charge and discharge at the same time. Be sure to use a power bank that meets the needs of your project.
What causes a rainbow screen on boot?
The rainbow screen is caused by a GPU error. When your Raspberry Pi is booting up, it will flash the rainbow screen as part of the GPU test. If the screen stays there, then there is likely an error with either your power source or your SD card. If you are using an new power source, this is most likely the culprit. If the power source in not new, try resetting your SD card as a file probably was corrupted at some point.