[maemo-users] Bluetooth power consumption, Re: Bluetooth headphones and mp3's

[From: Frantisek Dufka]

Simon Pickering wrote:
> 
> I thought Bluetooth was significantly lower power than Wifi...?
>

When radio is really used than wi-fi perhaps uses more power. However, 
it looks like the power saving features when connected to AP can really 
effectively help to reduce radio usage. Recently I added bluetooth usb 
dongle to my Asus WL500gx router and tried to use PAN via bluetooth 
instead of wi-fi with N800. My main motivation was to connect BT only 
devices to my network but I also hoped that I can save some battery in 
the tablet when listening to internet radio or could even disable wi-fi 
altogether (and thus be less dependent on specific kernel modules).

So far it looks like when the connection is mostly inactive, bluetooth 
uses more battery overall. With wi-fi I can leave the device always 
connected and won't lose much charge overnight. When tried this with 
bluetooth PAN connection (to same network, bridged in router) I have 
lost significantly more of battery. I'll do some more experiments 
especially with streaming audio (i.e. using the connection more) but so 
far it looks like BT does not help in the 'always on' scenario. Maybe 
this is specific to PAN networking and/or can be optimized somehow.

Frantisek