Bluetooth using battery?

Discussion in 'Hardware' started by Crito, Aug 26, 2008.

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  1. ashgfu

    ashgfu Pen Pal - Newbie

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    My sister, who has a Macbook, Says that having bluetooth on can run down your battery. Is she right? Is this just a Mac thing? I'd really like to know. If it did use power, wouldn't it only be like a minute amount?
     
  2. pattertj

    pattertj Tablet Tweaker

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    Bluetooth will run our battery down a bit... more if you are actively using it. According to Wikipedia, Bluetooth is rated in the mW's for power consumption. You might see a few minutes less life with BT on all the time. If you were transferring data the whole time, it would eat more life, maybe a noticeable amount...
     
  3. Frank

    Frank Scribbler - Standard Member Senior Member

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    BT will run our battery down, not only a bit, that's why I don't use BT when I use the battery.
    The difference is not only small it is huge.

    The problem is not the BT module which consumes so much power. It's the way BT is designed. If I turn on BT everything is still fine. But when I connect my BT mouse, keyboard, mobile phone or headset, then the CPU gets stressed a bit which results in a hotter CPU and a more power consuming CPU, because the CPU can't enter some super low power states.

    BT on with a connected, not necessarily active device means a hotter CPU, louder fan and 2 Watt more power consumption on my T2010, which would result in at least 1-2 hours less battery life on my tablet.
     
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  4. Crito

    Crito Scribbler - Standard Member

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    Bluetooth is supposed to be low power and short range, so shouldn't be that big of a drain... probably due to cr@ppy hardware and drivers, like a softmodem or anything made by Broadcom. :p
     
  5. Frank

    Frank Scribbler - Standard Member Senior Member

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    Well, the BT module supports 2.0 + EDR, the BT Stack is the Toshiba BT Stack, sadly I wasn't able to get the MS BT stack working. I tried a different BT USB stick, same effect.

    But you can test it yourself how much power BT consumes.
    Turn off BT and restart the machine, so we know that everything will be fine.
    Disconnect the laptop from the AC-Adapter and start RMClock. Then take a look at the CPU Load and the Discharge rate. Wait a minute and do nothing to get a low dischrage rate. Then switch on the BT device. Wait again and look at the values again, nothing great changed so far. Then connect a BT device. What happened? The CPU Load dropped (which means it consumes more power, strange but true) and the discharge increased.

    EDIT: According to the datasheet (mine is EYTF3CSFT, but I think they are the same) the BT device consumes only 33mA @ 3.3V = 0.1W. But the 2 Watt difference is because of the CPU stress.
     

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  6. Kyle Porter

    Kyle Porter Veteran Moderator Senior Member

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    Agreed. If not even more hours taken. On my 2710p i have it permanently disabled it consumes so much.
     
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  7. Crito

    Crito Scribbler - Standard Member

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    double post, but to reiterate, Broadcom is the source of all my problems.
     
  8. Crito

    Crito Scribbler - Standard Member

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    The reason CPU usage goes way up is because the firmware is in the driver, just like a softmodem. That proves that Broadcom makes cr@p cards, not that Bluetooth consumes too much power.
     
    Last edited by a moderator: May 18, 2015
  9. Frank

    Frank Scribbler - Standard Member Senior Member

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    I understand what you mean with the softmodem but I don't understand what Broadcom has to do with it. The module and the BT stack is not made by Broadcom. So why is Broadcom the source of all your/our problems?

    So you mean that the BT modules built in external devices, like mobile phone, headset, ... consume less power, because the firmware is built in the BT module and is not emulated via software, or do they also emulate the firmare via software, their microcontroller just consumes not so much power.
    But do you know if such BT modules exist, which don't stress the CPU, which control everything on its own or do you know a BT stack which does not stress the CPU?

    However, BT is great, but the way it is handled on a PC kills too much battery life to use it while using the battery.
     
  10. Crito

    Crito Scribbler - Standard Member

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    Yeah, I was responding to another thread in another forum and forgot where I was... Anyways, my Bluetooth cell phone headset using a single AAA battery that last for weeks. It also has little to no effect on the battery life of my cell phone. So the difference must be in the implementation of the technology, not the technology itself. In the case of Broadcom, I know they make softmodem-like cr@p.
     
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