Is the BLE power efficient while it's always connected to central device ?

[Tizana]

I'm wondering if the BLE is a low power efficient when it has to be always connected to the central device?

How it can be power efficient and the BLE while connected to central devices is periodically transmitting signal through the antenna to the central to keep both devices connnected. And we know that the antenna communication consume some mA and it's very high compared to the battery capacity.

My battery is LIR2450 and has a capacity of 110mA. I have on top of the nrf51822 three other circuits that consume an average of 100μA.

How long do you think my circuit can last with this battery knowing that these circuits are sensors and should be read once a minute and taking into account that my BLE should be always connected to a phone and update the characteristic value once per minute.

Can my circuit hold for hours , days or months?? I'm not asking for an exact time but an approximation.

Is there any solution to reduce the power consumption related to the antenna transmission ?

Regards,

[Jørgen Holmefjord]

Hi,

Yes, BLE is power efficient when in a connection. You can configure your connection parameters to allow the devices to sleep for a long time between each radio transmitt/receive. This means that even though the radio consume some current when in use, the average current consumption will be low.

There is a comprehensive guide about nRF51 current consumption in the tutorials section. For nRF52, we have a online power profiler where you can calculate the BLE current consumption from your settings. Unfortunatelu, we don't have such a tool for nRF51, so notice that the consumption of the nRF51 devices will be somewhat higher. The community user @nabjac has created an Excel sheet that can be used to calculate current consumption of nRF51 devices. Notice that I have not tested this tool, and cannot guaranetee it's correctness.

Best regards,

Jørgen

[awneil]

What, exactly, do you mean by "power efficient"? Compared to what?

[Tizana]

when i first designed my board i was planning to use the antenna once a minute by sending data to the phone. but later i figure out that to keep the connection between the peripheral and the central device the peripheral has to send some package periodically to the central device, which i wasn't expected to be like that at the beggining.

[Tizana]

thx Jørgen,

after i calculate the current consumption using the excel i figure out that the power consumption still low even it's always connected.

thx for all the information.