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I constantly read about the low power consumption of BLE and websites stating

Power consumption: Since a Bluetooth low energy device is in sleep mode most of the time - the maximum/peak current draw is only 15 mA and the average current draw is of only about 1 uA.

However whats confusing me is, when they mention sleep mode, does this mean the BLE module is not adverstising itself to the world and is undiscoverable?

I am trying to find out what actually occurs in sleep mode.

I am working on a small home project, and trying to find the least power hungry BLE, currently i have a standard BT module and when is discoverable mode it uses anywhere between 4mAH -30Mah and this is way to much.

Is it possible to get the 0.1mAH and still have the module advertising and then connect once a iPhone becomes in pairing range>?

Thanks

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    \$\begingroup\$ Short answer: No, in the lowest power mode, the Bluetooth radio is switched off entirely, so the device does not advertise itself. There are configurations used where the device powers on once every so many seconds, broadcasts, listens, then goes back to sleep. Slightly higher energy modes involve designs where reception is on, transmission is off until a connection signal is received. That last many partly address your need. \$\endgroup\$ – Anindo Ghosh Mar 5 '13 at 4:53
  • \$\begingroup\$ thankyou. Have you got any idea what BLE would use in that mode where reception is on, transmission is off? Are you talking uA or mAH? \$\endgroup\$ – Matt Mar 5 '13 at 5:26
  • \$\begingroup\$ mA, not uA. Certainly not mAh, as that's not a measure of current but of current capacity. \$\endgroup\$ – Anindo Ghosh Mar 5 '13 at 5:32
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    \$\begingroup\$ I found this, might be useful research.microsoft.com/pubs/192688/… \$\endgroup\$ – geometrikal Jan 10 '14 at 13:14
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Take a look at my answer here about low power radios:

Low-power wireless module strategy

The core problem is that BOTH receive and transmit typically take on the order of 10mA to 30mA for integrated radios.

Therefore to get average power down you must use some kind of radio duty ratioing technique (there are many). As an example, ContikiMAC can route traffic in a sleepy router network with about 400uA average.

I'm not too familiar with BTLE but your numbers are no too surprising to me. I've seen demos of BTLE devices that use a coin-cell and have a run-time around 1 week. This would match the numbers you are seeing.

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  • \$\begingroup\$ Thanks all for the posts, very insightful . I think I'll have I investigate the option of powering the BLE on every 2 second, broadcast, listen and then into a deep sleep until the bext cycle in 2 seconds, Trying to find any concrete info on battery life is provin to be very difficult. I also need to be powering a sensor that uses less than 1mA for 8 hours of the day. I don't know If this will be possible to get around 6 months battery time even with the lowest power consumption BLE and sensor in this arrangement. \$\endgroup\$ – Matt Mar 8 '13 at 22:56
  • \$\begingroup\$ Re: battery life --- it's true, the data is sparse. One problem is that most batteries are simply not rated to last for years. tadiranbat.com is one exception though. Some of their cells have charts that go out to 50 years. You can buy their batteries on Mouser. \$\endgroup\$ – Mariano Alvira Mar 20 '13 at 16:59

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