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Discussion in 'MacBook Air' started by AtmChm, Feb 26, 2011.
Does anyone know which takes more power/drains the battery more?
What do you mean "USB ethernet"? Do you mean WiFI vs USB? WiFi vs Ethernet? USB vs Ethernet? WiFi, USB and ethernet are 3 different things.
I'm gonna take a really huge leap here and guess that he wants a power comparison between built in wireless and the USB Ethernet dongle.
I wish I could give you the answer, because when I have the need to plug in the USB ethernet dongle normally I plug in power at the same time.
The poster probably means wi-fi vs. Ethernet via USB adapter since this is a Macbook Air forum and all. I am not sure of the answer to the question though. I would think the difference would be negligible.
I missed that it was a MBA forum. WiFi would most likely drain the battery faster.
Wifi uses way more power. Double atleast. USB ports only use a few watts.
You do realize a typical wifi connection from a laptop is around 30mW right? A USB device can be up to 2.5 watts, that's 2500mW. That doesn't necessarily mean the usb dongle uses 2.5 watts but if wifi actually transmitted at double what a usb port can use, which is what you're suggesting, you'd need a license from the fcc to operate it.
Now the wifi chipset will of course use more than 30mW, as that's just the transmit power, but I'd be VERY surprised if it used 5+ watts. In fact, I'd be surprised if it used 2.5 watts.
Easy way to test it. Set your battery indicator to show you time remaining. Let it sit idle for a bit to get an accurate reading. Turn airport off, Then plug your usb dongle in and connect it to an active port see if time remaining drops or increases.
Ok, so I just did this very test...
Air Port On: 8:36
Air Port Off: 8:52 - 9:38 fluctuating
Air Port Off w/USB Dongle connected: 6:36
Even if we factor in a certain margin of error, it seems the usb ethernet adaptor uses quite a bit more power than wifi. The time remaining has actually dropped to 6:05 with the usb dongle attached just while typing this reply. (and i'm not typing this on my MBA)
Also, the USB Adaptor gets noticably warm after just a few minutes of using it, so it's certainly sucking up some juice. This was with no real data being trasmitted, should this be a very active connection I think the results would be even worse as USB ports tend to have some CPU overhead.
I've noticed this exactly, ethernet itself takes less power than wifi would, but with the USB adapter, it uses much more power than wifi does.
That's what I based my assumption on. Ya learn somethin' new every day!
The battery usage will be almost unnoticeable between the two wired mediums, however WiFi is notorious for chewing on battery. But still not enough that you would need to worry. Just turn down the screen brightness if you're concerned about battery usage.
USB and Ethernet both require less power to transfer data than WiFi. Also, you don't risk connection issues with a wired connection (at least to the extent of issues that may come up using a WiFi connection). Then again, WiFi is wireless!
If you have the opportunity to plug it in, do it, but I have yet to use my Apple Ethernet adapter.
This is incorrect as the wired ethernet takes more battery than wifi does. :\
Thanks for all the insight. I was asking about WiFi vs. the usb ethernet connector you can get for the MBA.
I have also noticed the usb ethernet connector gets warm during use, which made me wonder if it is engaging in a lot more activity than the wifi is in terms of power consumption. I regularly use my MBA in settings where I have the option to use wireless or connect to the wired network via the usb ethernet connector. I was just curious if one would noticeably use up the battery faster.
Thanks again for all the insights!
...for anyone interested, I got a USB ethernet adapter and USB extension cable from www.monoprice.com for less than $9, here's the link to the adapter:
...its not a "gigabit" adapter but you'd never realize those speeds on USB2 anyway and it was "plug and play" on my MBA!
Yes sorry for not being clearer. I was talking about Wifi as a whole. A typical ethernet port uses 350mW which is not alot. Now im not sure if going thru the USB port requires more wattage but i dont think it would. But yeah, you're right. OP should test it out.
Well I already tested it in my second post in this thread. My findings were verified by another member (impulse462). A native ethernet chipset may be another story but it seems the usb adaptor is quite inefficient when it comes to power usage. This is using the Apple branded adaptor.
This is an interesting comparison, while I would indeed believe that an usb to ethernet adapter would take more power than a native wifi card. I am not sure which would be faster. Although if you are trying to maximize battery, I would start with the bigger factors that affect it first(such as the cpu) then move to the smaller items that affect it. Thanks!