Bluetooth 4.0 and idle battery drain

j-a-x

macrumors 65816
Original poster
Apr 15, 2005
1,485
177
Houston, Texas
I know Bluetooth generally uses a lot of battery power, and I know that the new Bluetooth 4.0 chip in the new iPad supports low power Bluetooth devices. However, does anybody know if Bluetooth 4.0 significantly drains the battery if Bluetooth is left on but no devices are connected? I know on the iPad 2 it did but since the new iPad has a new Bluetooth chip I was wondering if it might drain less power.
 

Gathomblipoob

macrumors 601
Mar 18, 2009
4,719
3,533
I know Bluetooth generally uses a lot of battery power, and I know that the new Bluetooth 4.0 chip in the new iPad supports low power Bluetooth devices. However, does anybody know if Bluetooth 4.0 significantly drains the battery if Bluetooth is left on but no devices are connected? I know on the iPad 2 it did but since the new iPad has a new Bluetooth chip I was wondering if it might drain less power.
I've noticed no faster battery drain with Bluetooth turned on. I had Bluetooth on by default for a few days until I discovered it and turned it off. No noticeable difference to me.
 

aypues

macrumors regular
Feb 25, 2012
153
14
San Diego
Thats a good question. I know that peripherals using BT 4.0 are supposed to last a REALLY long time on a single charge...like up to 6 months for a mouse/keyboard combo. But if the the iPad has to communicate with an older device that's BT 2.1 it probably uses the older profile which drains more energy. Not sure tho.
 

brand

macrumors 601
Oct 3, 2006
4,363
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127.0.0.1
Since it needs to remain backwards compatible I would assume that it probably uses close to the same amount of power as the older iPads did but that's just an assumption.
 

bluetoothguy

macrumors newbie
Mar 30, 2012
1
0
The new iPad uses a new "dual mode" Bluetooth radio that can speak to a classic Bluetooth device in one mode or to a new low energy device in the other. The Bluetooth Special Interest Group calls devices with the dual mode capability "Bluetooth Smart Ready".

If the new iPad were communicating with a classic device, it would use the same amount of power you've seen previously--nothing different.

On the other hand, if the new iPad were communicating with a low energy device, what the SIG brands "Bluetooth Smart", it would consume significantly less power as the low energy specification is MUCH more power efficient.

You can find more details here if you like: http://www.bluetooth.com/Pages/Bluetooth-Smart-Devices.aspx

Hope that helps!
 

j-a-x

macrumors 65816
Original poster
Apr 15, 2005
1,485
177
Houston, Texas
The new iPad uses a new "dual mode" Bluetooth radio that can speak to a classic Bluetooth device in one mode or to a new low energy device in the other. The Bluetooth Special Interest Group calls devices with the dual mode capability "Bluetooth Smart Ready".

If the new iPad were communicating with a classic device, it would use the same amount of power you've seen previously--nothing different.

On the other hand, if the new iPad were communicating with a low energy device, what the SIG brands "Bluetooth Smart", it would consume significantly less power as the low energy specification is MUCH more power efficient.

You can find more details here if you like: http://www.bluetooth.com/Pages/Bluetooth-Smart-Devices.aspx

Hope that helps!
My question was, how much power will it consume if I simply leave Bluetooth on and am not communicating with any devices. Will it still drain the battery as much as the previous iPad? I am guessing yes.

And I am guessing that when communicating with a new low power bluetooth devices, the bluetooth device will use much less power but the iPad will use as much power as communicating with an older Bluetooth device.
 

burlow

macrumors newbie
Jun 8, 2012
1
0
No noticeable battery drain

I left my 4S (fully charged, bluetooth on but not connected) next to my bed last night. 7 hours later, it was only down to 97%. Factor in 3G radio and whatever else runs in the background (mail fetching etc) and I thought it would be more than 3% just from those.

It appears that BT uses next to no power when idle.