Low Power Single Cell Li-PO/Li-ion Modifications for Raspberry Pi

07 September 2013

Hi everyone,

I have a Raspberry Pi web server(pi.melihkarakelle.com)(temporarily unavailable) and I want to power it with solar energy. The main problem is the high current consumption of the Raspberry Pi Model B (330mA).

The solution is very simple. Just remove the network/USB hub IC and solder two jumper wires (between R36 and R37) to enable one USB port without this IC.
Please read this blog first

After this hack, my Pi runs at 190mA at 5V, including the WiFi USB dongle. But this is not enough. The system runs at 3.3V, and the onboard linear voltage regulator drops the 5V to 3.3V, which is a complete waste of energy. My second target was to use a better LDO regulator.

I replaced the original regulator with MIC2502-3.3
The MIC2502 is a very low dropout regulator IC, and its output is 3.3V when you supply it with 3.4V-16V. If your supply drops to 3.1V, it still gives about 3V, which is enough to run your Pi.

Here is a macro photo of the new regulator (you need fine soldering skills to do this).

Now my Pi runs from a single-cell Li-Po, Li-ion or USB without any extra modification.

You can save another 20mA by switching off the PAL/HDMI outputs. Add this command to your startup script:

/opt/vc/bin/tvservice -off

Now my web server runs on only 170mA 🙂

Now my 5V 500mA solar panel will be enough to run my Pi and charge the single-cell Li-ion battery for the night.

I will share the next stages of the project in future posts.

Etiketler: cell, lithium, low, mic2502, Pi, power, Raspberry, single

2 responses to “Low Power Single Cell Li-PO/Li-ion Modifications for Raspberry Pi”

Melih Karakelle

30 September 2014

RPi is working with 3.3V, so using a linear regulator is a waste of energy. New RPi Compute Modules are offering dual switch mode regulators for both (1.8-3.3) core voltages. I guess this is more efficient than linear regulators.
Using a wireless dongle is more energy efficient than using ethernet because of ethernet hardware design. Ethernet lines requires high current pulses to avoiding from the signal noises. But Wifi modules using maximum 10mW RF waves for communication and it’s reducing depending on the distance between devices.
Jonathan Price

30 September 2014

Do you know if the switching regulator on the B+ and upcoming A+ will work at these lower voltages? They seem to consume less power at 5v.

Is an LDO linear regulator really more efficient at 4.2v than the 5v boost converters other people are using?

I notice you’re connecting via a Wi-Fi adapter. Other people have reported that these adapters can consume a lot of current. Does it really use less power than the built-in ethernet when the network is connected and active?

Low Power Single Cell Li-PO/Li-ion Modifications for Raspberry Pi

2 responses to “Low Power Single Cell Li-PO/Li-ion Modifications for Raspberry Pi”

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