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How much current do small USB-WiFi routers draw?

Posted on Monday, August 27th, 2012 in wireless by DP

Jbeale reviewed how much current small USB WiFi routers draw. His intent is to connect them to the Raspberry Pi which can only provide 140mA over the USB port. It turns out that from Internet connectivity the routers draw under 100mA, but if used in high speed LAN operations the current draw jumps over R-Pi’s threshold.

Just compared two small USB-WiFi N adapters from ebay. Both devices connected easily from my WinXP laptop to my Linksys WRT160Nv2 router, reporting excellent signal and 72 Mbps link speed. It is interesting to see that both devices keep under the 100 mA limit while working the internet at my DSL speed. But going to a machine on the LAN, the speed goes up and the current draw goes up with it, above 150 mA which is more than the unmodified RPi USB port can reliably provide. So I’d expect either of these devices would be perfectly reliable for internet browsing used direct in the RPi without a supply, but UNreliable for heavy LAN use (eg. high-bitrate video streaming). …Unless you have faster internet than I do, in which case, web use might hit overcurrent also.

Via the forum.

This entry was posted on Monday, August 27th, 2012 at 7:00 pm and is filed under wireless. You can follow any responses to this entry through the RSS 2.0 feed. You can skip to the end and leave a response. Pinging is currently not allowed.

2 Responses to “How much current do small USB-WiFi routers draw?”

  1. maxf says:

    Sorry, but WiFi router != WiFi adapter. SCNR ;)

  2. JBeale says:

    Thanks for putting that up- there’s another addendum: this issue is now less critical on the very latest R-Pi boards (shipping as of last week) because of the change you see here:
    https://picasaweb.google.com/109928236040342205185/Raspberry_Pi#5780498170375008498
    (USB fuses F1,F2 are now 0-ohm jumpers. Still limited by 750 mA input fuse though)

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