Raspberry Pi Power Pack



I have built the PiCy with great success! However when the time came to use the Power Pack instead of a mains cable to power the pi, it boots and is fine, except for my wifi dongle, I can see it trying to connect to the router but receiving no packets back, and after a few attempts gives up and continues with booting up the Pi.

After re applying mains power its working fine again! My WiFi dongle is:


Any suggestions would be great?
Thanks , Sam

piborg's picture

Have you tried using the other USB port?

The reason I ask is we had a similar problem with a Bluetooth dongle that would not start properly on battery supply that we "fixed" by using the other USB port.

If you have something else on the other USB port I would also try again with only the WiFi attached.

We have had one of the supplies we sell powering a Raspberry Pi with the same WiFi dongle successfully, but it might be close to the limit of what the supply provides in terms of current.

If it is using wireless 'n' it will probably try and use more power then with 'g', we have not tried as we do not have a router capable of 'n' in the office anywhere.

Thanks for your reply.
I tried it in the other USB port, and the dongle didn't even have its power light come up and the rpi didnt even know it was there. so I got lucky with the original port it was in! I also ensured it was the only item on usb.

I only have an 'n' router so cannot try using a 'g' router. Is there a wifi dongle you would recommend that will definitely work with the power pack you sell?

piborg's picture

We tried some experiments this morning and found the following:

The WiFi we sell appeared to work fine, we could SSH in and get the RPi to perform some tasks.
We also tried the same thing with a PicoBorg attached without any problems.

The EW-7811Un we have in the office was unreliable, it sometimes worked and sometimes did not.
With a PicoBorg attached it did not work at all, I presume the slight drain due to the 3.3v logic is enough to prevent it getting the full power it requires.

This was all tested with a Rev 2 model B Raspberry Pi with the latest binary download of Raspian and a 'g' router (WPA2) in the office.

In summary we would suggest trying the WiFi chip we are selling: http://piborg.org/accessories/wifi which is based on a Ralink chipset instead of the Realtek used by the EW-7811Un (it seems to require less power).

Make sure the battery is fully charged before trying another chip, also your router may give a different IP address when using a different chip.

If you do buy one from us and it still does not work we will refund your order, also you can keep the WiFi anyway for the hassle caused :)

Brilliant, thanks for your help!

Hello Again.

Unfortunately I am still having the exact same problem with this new WiFi dongle D:
Is there any other suggestions?


piborg's picture

Struggling to think of ideas now, maybe the following will help:

1. Disable the power management
Many people have had issues with power management, see this thread for instructions:

2. Try changing the encryption from CCMP to TKIP
With a lot of routers this will prevent the dual-channel behaviour of 'n' and may reduce the power drain caused by the WiFi transmitting

3. Try forcing the WiFi to the 2.4GHz frequencies
To do this you need to add the following line to /etc/wpa_supplicant.conf
freq_list=2412 2417 2422 2427 2432 2437 2442 2447 2452 2457 2462 2467 2472 2477 2482

With the changes my /etc/wpa_supplicant.conf looks like:

ctrl_interface=DIR=/var/run/wpa_supplicant GROUP=netdev

        freq_list=2412 2417 2422 2427 2432 2437 2442 2447 2452 2457 2462 2467 2472 2477 2482

I cannot really confirm if these changes will make any difference but it is probably worth a try.

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