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

Hi Everyone,

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

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

After this hack, My Pi is working with 190mA at 5V including WiFi USB dongle . But this is not enough. The system working with 3.3v and on board linear voltage regulator dropping the 5v to 3.3v. This is compleately waste of energy. My second target is using better LDO regulator.

I replaced the original regulator with MIC2502-3.3
MIC2502 is very low drop out regulator IC and output is 3.3v when you supply it with 3.4v – 16v . If your supply drops to 3.1v, It will give already 3v output and still enough to working your Pi.

Here is the macro photo of the new regulator (you need fine soldering skill to doing that)

Now my Pi working with single cell Li-Po, Li-Ion  or USB without any extra modification.

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

/opt/vc/bin/tvservice -off

then my web server working with only 170mA 🙂


Now my 5v 500mA solar panel will be enough to running my Pi and charging the single cell Li-Ion battery to the night.

I will share the other stages of the project on my new posts.

 

Published by

Melih Karakelle

Maymun iştahlı ArGe mühendisi

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

  1. 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.

  2. 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?

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