Everything You Need to Know About Low Battery

What is a low battery?

A low battery indicates a low battery level with other words like low power, low charge, or low voltage. A low battery suggests the condition of a battery that needs to be replaced or recharged.

Difference between hydrogen fuel cells and lithium batteries

Different types of batteries are treated differently when they are low on power.

A low charge requires replacement for non-rechargeable batteries. Rechargeable batteries are used in a cycle: power to load—low charge—charge—power to load—low charge—charge.

However, the battery should not be too low. All rechargeable batteries have a control circuit to monitor and maintain battery status. This circuit will be compromised if the battery voltage becomes too low, reducing or cutting off the current from the battery to the load. Changes in battery voltage can be monitored using a device such as a voltmeter to keep abreast of battery status and take appropriate action.

If the battery is frequently undercharged and the charge drops faster than normally expected, this is an indication that the battery also needs to be replaced, which usually happens with old batteries or batteries that are not kept in good and desired condition. As a general rule, when using lithium-ion batteries, the charge capacity should be maintained at 20-80%. This will help to prolong battery life and maintain optimum performance.

Some causes of low battery

A low battery usually occurs for several reasons:

Excessive use

It is normal for prolonged use of an electronic device or vehicle to drain the battery and cause the charge to become low. When a lithium battery is nearing depletion, the device will usually give a warning or indicate that it is low on power, but will still provide power for some time. Simply recharging the battery will solve the problem.

Aging

Batteries age over time and their capacity and performance will decrease, resulting in a lower charge. As the battery charge/discharge cycle progresses, the electrolyte, positive and negative materials, etc. will undergo physical and chemical changes. Their capacity and performance will decrease, resulting in a lower charge. The rate of this aging depends on the type and material of the battery.

Ambient temperature

In a high-temperature environment, the effective capacity of the battery will be reduced. Low temperatures can cause the rate of chemical reactions within the battery to slow down, reducing the usable capacity of the battery.

Application issues

Certain applications can consume large amounts of power in the background, causing the battery to drain quickly.

Battery malfunction

There may be problems with the battery itself, such as damage, overheating, or other malfunctions that result in reduced performance.

Minimum voltage for common battery type

Common batteries include lithium-ion, lead-acid, nickel-cadmium, and sodium-ion. Different batteries have different minimum voltages below which battery life is compromised. Lithium-ion batteries have a minimum voltage of 2V-2.5V, and lead-acid batteries (including gel batteries, AGM, DCB, etc.) have a minimum voltage of 1.6V-1.9V.

For Ni-Cd batteries, the minimum voltage for Ni-Cd cells is 1.0V-12V per cell, and for sodium-ion batteries, the minimum voltage drops to 2.5V. Low-voltage batteries have these voltages.

It is important to note that these values are approximate standard ranges and the actual minimum voltage may vary depending on the brand, design, or use of the battery. Continuing to use the battery until the voltage falls below the recommended minimum may result in degraded battery performance, damage, or even a safety hazard. Therefore, when using electronic devices, keep an eye on the battery level and recharge promptly to avoid problems caused by low voltage.

What happens when the battery is low?

A low battery can have a variety of effects on your device, depending on the type of device, the type of battery, and the specific charge level.

• Limited functionality: Some devices may automatically turn off certain features or limit the use of features to reduce power consumption.
• Sudden shutdown: In extreme cases, a low battery may cause a device to shut down suddenly, resulting in loss of data or interruption of work.
• Data loss: If the device does not save data before the battery runs out, a sudden shutdown may result in data loss.
• Risk of damage: Some devices may be at risk of damage when the battery is extremely low, especially when performing critical operations or running applications. For lithium batteries, when the voltage drops below 2V. The battery is over-discharged and the negative electrode dissolves into the electrolyte, making it susceptible to capacity loss or internal short circuits.
• Temperature control problems: A low battery can compromise the device's temperature management function, increasing the risk of the device overheating or overcooling.
• Erratic performance: Some devices may experience erratic performance when the battery is low, as evidenced by application crashes or slow device response.

Therefore, it is very important to keep the battery charged when it is low. Some lithium batteries with intelligent management systems can detect the battery voltage. This prevents short-circuiting and overheating caused by excessive discharge and ensures safe use of lithium-ion batteries.

What are the signs of a low battery?

Once you know the consequences of a low battery, you can probably determine the signs of a low battery. Low battery signs can be seen in the performance of the device, the battery parameters, and the battery's condition. Often, devices that use batteries will start to emit such signs, for example, when a car's battery is low, it will start to make noise. The laptop screen's brightness decreases, the game console's screen stutters, the charge indicator flashes or turns red, and so on.

A low battery can also be measured by a standard battery parameter, SOC, or State of Charge, which indicates the ratio of available battery power to the amount of power the battery can store. Many electrical devices, such as drones, electric motorcycles, and medical equipment, also have screens that display the battery's SOC.

Some batteries, such as lithium-ion batteries, also display their charge. You can set up a display to show the SOC of the battery pack or even the battery alone in real-time, or you can set up a Bluetooth function to show the SOC on a mobile app. This allows you to be intelligently alerted when the charge is low, or potentially low if the battery has not been used for a long time.

How to solve the low voltage or voltage drop of lithium batteries?

Voltage drop is that the voltage gets lower and lower when charging, as the battery discharges, the voltage will drop, the charging cut-off voltage of a ternary lithium battery is 4.2V, and the discharging cut-off voltage is 2.5V, within this range, it belongs to the normal voltage drop in the process of discharging the battery, and the voltage lower than this range is called the extreme voltage drop, which is harmful to the battery, and it will turn into a low power battery.

Solutions to avoid extreme voltage drops are listed below:

• Charging the battery: Be sure to use a charger that matches the type and specifications of the battery and follow the proper charging procedure. Care should be taken to avoid overcharging during the charging process.
• Avoid over-discharging: Keeping the battery at 20%-80% and not discharging it completely can effectively prevent the battery voltage from dropping too quickly.
• Reduce electrical load: Reducing the load on the battery, such as the electrical equipment connected to the battery, can reduce the voltage drop.
• Maintain operating temperature: Keep the battery operating temperature within a reasonable range; too high or too low a temperature will affect battery discharge and voltage changes. The operating temperature of Li-ion batteries is -20-60°C, and the optimal temperature is 20-25°C.
• Check the charger and cables: Make sure the charger and charging cables are working properly, sometimes the problem is with the charger rather than the battery itself.

Will a low-voltage charged battery work properly?

For most batteries, charging at low voltage It is recommended that the battery charging voltage is the same as the input voltage, charging voltage is too low battery can temporarily work normally, but long-term use of the battery has an impact on the charging voltage is too low will also slow down the charging speed, so it is very important to determine the state of charge of the battery to ensure that the battery charging is carried out normally. According to different types of batteries, and different discharge conditions, the battery discharge termination voltage is also different, the general provisions of the termination voltage will be reduced with the increase in discharge current.