Operating time of portable speakers without recharging

Portable acoustics have been booming in recent years. It is convenient to take a portable speaker with you to nature, which is relatively compact and does not require wires. But for many it is important how much acoustics can work without recharging. Manufacturers usually indicate the maximum runtime under ideal conditions and at 50% sound volume. Let’s figure out what factors it depends on, and check in practice how long the speaker can work at different volume levels.

Dependence of the operating time on the current consumption
Let’s turn to theory first. Obviously, the battery life depends on the battery capacity. But it is also necessary to take into account another factor – the current consumed by the column. It is wrong to estimate the duration of work only by the capacity of the battery.

Disassembled JBL Pulse 3 column with a 6000 mAh battery in the right hand

For example, there is a speaker with a current consumption of 400 mA and a 2000 mAh battery, and there is another speaker with a current of 1000 mA and a 4000 mAh battery. Recall that capacity is measured in milliampere-hours (mAh). That is, this is the product of current and time. Thus, the battery life of the first column will be five hours (400 × 5 = 2000), and the second – only four hours (1000 × 4 = 4000), despite the battery with a larger capacity.

Therefore, you should not pay attention to the capacity figures indicated by the manufacturer. Better look at the maximum battery life and read reviews about autonomy in user reviews .

Dependence of operating time on different volume levels
As the speaker volume increases, the signal strength increases, which is transmitted by the amplifier to the speaker, which converts this electrical signal into sound. The amplifier consumes more energy, and accordingly, the current drawn from the battery also increases. But the change in current consumption will not be proportional to the change in speaker volume. Why it happens?

To begin with, it should be noted that the sensitivity of the human hearing aid depends on the volume level. At low levels, the sensitivity is greater, and at higher levels, it is less. That is, a change in loudness by the same amount in the area of ​​its small values ​​and in the area of ​​large values ​​will be perceived by a person differently. It has a logarithmic relationship.

Dependence of hearing sensitivity on sound volume

To compensate for this perception, loudspeaker manufacturers make non-linear volume control. In the initial region, the rate of rise of the sound level is made lower, and then it is increased.

Dependence of the actual volume level on the value of the adjustment scale

This gives the person’s hearing aid the feeling of linear and smooth sound adjustments.

The resulting dependence of the perception of the loudness level by a person

It turns out that at a value of 50% of the speaker control scale, the actual value of the actual volume will have a much lower value (about 10%). It is easy to understand that at 100% volume, the speaker’s battery life will be significantly reduced. Below we will verify this statement in real life.

How does the ambient temperature affect?
The battery life will be significantly reduced if you use the column in the cold. But there is no need to worry – this is a temporary effect.

Dependence of battery capacity on temperature

Lithium-ion batteries have a peculiarity, at low temperatures, they partially lose their capacity. This is due to the slowing down of chemical processes in them. The process is reversible – when the temperature rises, the capacity is restored.

How does the degree of battery wear and tear
Any rechargeable battery has a limited number of charge-discharge cycles. As they are depleted, the capacity gradually decreases. The established resource of lithium-ion batteries, which are used in portable speakers, is on average from 500 to 1000 full cycles.

Dependence of the residual battery capacity on the number of charge-discharge cycles

The more often you charge the speaker, the faster its battery life will decrease. This is normal, natural wear and tear.

Testing at different volumes
Let’s put the theory into practice. Let’s see how long a portable speaker will work at 20, 50, 80 and 100% volume control. To do this, we use JBL Charge 3 acoustics and a OnePlus Nord smartphone. The column was purchased on February 22, 2019, that is, the service life is approximately two and a half years.

The test system is pretty straightforward

Testing was carried out in an ordinary apartment at a temperature of 24 ° C, with a full battery charge and the backlight turned off. Due to complaints from households, for volume levels of 80 and 100%, the speaker had to be moved to the balcony, where the temperature fluctuated around 16-18 ° C.

Indication of volume levels 20, 50, 80 and 100% on the JBL Pulse 3 speaker

The signal “white noise” was reproduced, which was transmitted by the smartphone via Bluetooth. The charge level was controlled remotely using the proprietary JBL Portable application .

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After several days of testing, we get the following results:

At 20% volume, the speaker worked for approximately 12 hours 10 minutes, at 50% – 10 hours 50 minutes, at 80% – 8 hours 25 minutes, at 100% – 5 hours 55 minutes. It is worth considering that at high sound levels, as noted earlier, the temperature was lower, and the concrete wall separating the balcony from the room interfered with the passage of the Bluetooth signal.

The manufacturer claims up to 12 hours of battery life, but detailed clarifications are not given:

Let us assume that this figure is obtained at 50% sound level under normal climatic conditions . In our case, taking into account the wear of the battery for more than two years of operation, the time decreased by about an hour.

It can be concluded that, in terms of the consumption of electrical energy per volume unit, a level of 50% is the most profitable mode of operation. At 80% and 100%, the battery is discharged disproportionately faster than the volume level increases, which corresponds to the logarithmic law. To prevent premature deterioration of the speaker battery, it is best to use it in portable mode at medium volume or lower. And if you need a loud sound, power it from the mains.