Temperature compensation: What is compensated is not actually the temperature?

How do batteries work?

In communication power supply, batteries play an important role in ensuring uninterrupted power supply for communication equipment. So, how do batteries ensure the provision of reliable backup power?

When the battery needs to store electrical energy, it converts electrical energy into chemical energy through chemical reactions and stores it. This process is called charging, which is similar to storing water in a pool.

When the battery needs to provide electrical energy, it converts chemical energy into electrical energy through chemical reactions. This process is called discharge, which is similar to drawing water from a pool.

Why is temperature compensation needed?

During the process of charging/discharging the battery, the chemical reaction is sometimes too strong/slow, causing the battery to not work properly. In order to ensure the normal energy conversion and protect the battery health, "temperature compensation" is required.

Next, we introduce the two main factors that affect the intensity of battery chemical reactions:

(1) Temperature: The intensity of the battery's chemical reaction is closely related to temperature. Under the same charging voltage conditions:

• As the battery temperature increases, the chemical reaction becomes more intense.
• The battery temperature drops and the chemical reaction becomes more gradual.

(2) Float charge voltage: Correct float charge voltage is the basic guarantee for battery health. At the same temperature:

• As the battery float charge voltage increases, the chemical reaction becomes more intense and the charging current increases.
• The battery float charge voltage is lowered, the chemical reaction is smoother, and the charging current is reduced.

Since our communication power supply is used in a variety of scenarios, the actual ambient temperature of the battery varies greatly, which has a great impact on the chemical reaction inside the battery. At this time, the impact of temperature changes on the battery can be weakened by adjusting the "floating charge voltage".

• When the battery temperature is high, reduce the float charge voltage to slow down the chemical reaction.

• When the battery temperature is low, the float charge voltage is increased to enhance the chemical reaction.

The function of ensuring normal energy conversion of the battery by adjusting the "floating charge voltage" is "temperature compensation".

Reasonable implementation of "temperature compensation" can effectively extend the service life of the battery and improve the battery's performance.

How to achieve temperature compensation?

Taking the communication DC switching power supply as an example, to achieve temperature compensation, the communication DC switching power supply needs to be able to monitor the temperature of the battery in real time and be able to adjust the floating charge voltage of the battery in time according to the measured temperature.

The monitoring unit in the communication DC switching power supply has the ability to monitor temperature and adjust the floating charge voltage.

For communication DC switching power supplies using 48 V battery packs, temperature compensation is usually based on 25 °C, the float charge voltage is based on 53.5 V, and is adjusted at -3 mV/°C per (2 V) battery.

For example, for a 48 V battery pack for communication power, if the battery temperature is detected to be 10 °C, the float charge voltage is calculated as follows:

V float=53.5 V+(10°C-25°C)×(-3 mV)×24=54.58 V

For communication power supply, the battery float charge voltage is higher than 53.5 V in winter and lower than 53.5 V in summer. This is the result of temperature compensation, which is conducive to better management and protection of the battery.

Can the battery be kept healthy by relying solely on “temperature compensation”?

After reading this, I believe you have understood the basic principle of temperature compensation. But can the battery health be guaranteed by relying solely on "temperature compensation"?

Answer: Of course not, temperature compensation is not omnipotent!

The temperature compensation function can minimize the impact of temperature on the battery, but it does not mean that it can be used at any temperature by relying on this function.

• Long-term low temperature: The floating charge voltage increases. If the floating charge voltage is too high for a long time, it will accelerate the corrosion of the metal grid in the battery and even cause the lead-acid battery to "lose water", which will shorten the life of the battery.
• Long-term high temperature: The floating charge voltage is reduced. If the floating charge voltage is too low for a long time, the battery will not be fully charged, affecting the capacity of the battery. This will greatly reduce the efficiency of the battery.

Especially in sites where the ambient temperature changes greatly, the temperature has a great influence on the chemical reaction speed in the battery. If the battery capacity is not fully utilized, the battery life will be shortened if the battery only relies on its own temperature compensation function.

Therefore, in order to maintain the battery's optimal operating temperature of 20℃~25℃, in addition to its own temperature compensation function, it also depends on air conditioning and fresh air systems.