Re: Which uses less power

Arno Welzel <usenet@arnowelzel.de> wrote:

sms, 2024-10-22 22:05:
 

On 10/21/2024 11:15 PM, Bill Powell wrote:

Which uses less of the phone's battery power on long trips?
>
Playing long podcasts with the Android speaker as the output?
Playing long podcasts with a Bluetooth speaker as the output instead?
>
Any idea?

 
Speaker wattage is about 3W.

 
So it draws around 1 ampere when running at around 3 volts? Really?
 
Maybe the theoretical output wattage is 3 watts, but a smartphons
speaker will also just draw a few 100 mA which will be around 0.3 to 1 watts
 

Bluetooth uses about 2.5mW.

 
No. Depending on how actually use Bluetooth, the power requirements can
be much higher:
 
<https://novelbits.io/ble-power-consumption-optimization/>

That article addresses power consumption at the BLE device, not at the
smartphone powering its BT radio.  In the phone, not in the BT devices,
does the BT radio in the phone consume more power when a BT device is
connected to the phone's BT radio?  I would think the BT radio might
also go to sleep unless there was a connected BT device yet I don't
recall reading that BT lets the radio in the phone know when a BT device
is asleep, just that a BT device is connected.

So the speaker uses more than 3000x the power.

 
Wrong assumptions lead to the wrong conclusion.

But a BLE headset is not drawing power from the smartphone.  BT at the
phone is sending a radio signal, not transmitting power over the air.
The BLE device itself, like a BT headset, has its own battery. 

While the OP could turn off the BT radio in his smartphone when using
the phone's speakers, most likely he leave BT always enabled.  So, while
using the speakers, his phone is still powering the BT radio.  He is
consuming power for both components in his phone.

The OP should check how long his BT headset lasts to know if it will
last for the duration of his trips.  If not, he could use the BT headset
until its battery went dead, and then switch to the phone's speaker
assuming he doesn't care about annoying others with his noise.

Presumably the OP has a smartphone with no headphone jack.  My old phone
does.  My expectation is that a headset connected to a headphone jack
consumes less power than the speakers in the phone if only in having to
use less power to move the speaker's diaphragm less distance to effect
the same volume level in your ears.  Likely the OP doesn't have a
headphone jack, and why he asks about speakers versus BT headset.

I don't believe the OP was asking about how much the BLE device's
battery got consumed during its use, but rather the impact on the
phone's battery up-time when using its BT radio.  Since RF isn't being
used to transmit power to the BLE device, just a signal, the impact of
BT usage in the phone's power consumption would be between its sleep and
active modes.  A BLE headset would consume much less power from its
power source than a BT boombox from its power source, but neither is
using the phone's battery other than keeping the phone's BT radio
active. 

I can use a flashlight to operate a photoelectric cell that rings a
doorbell or engages a garage door opener.  The flashlight's power
consumption is not affected by the power needs of the doorbell or garage
door opener.  Only being off or on affects the flashlight's battery
life.  Obviously the longer the flashlight is on means more total
battery drain, the the devices the flashlight triggered do not affect
the drain on the flashlight in its on-state.