subject: Battery Charging Technology [print this page] A good solar electronics product stands out to an optimal state of charge determination. This is the key for battery long service life.
What does SOC (state of charge) mean?
SOC means that the current of the battery is fully charged at 100% and the lowest discharge value is 0%. All other values between these numbers can be reached, but the battery should not go below 30%. If it is below 30%, the batteries can go to a dangerous deep discharge level, which will decrease the service life of the battery.
Cell capacity gradually reduces as a cell ages. The actual remaining capacity depends on many parameters such as temperature, age, etc. It is possible to gain an approx. estimate of the batterys current remaining capacity. As the age of the battery increases, however, the rated capacity can change significantly, which also means that the available capacity can be strongly distorted.
Why is a SOC determination so important?
During charging, the solar charge controller must know when the battery is fully charged so that the battery is protected from overcharging at the right moment. The charge controller then disconnects the battery from the module so that the battery charging is stopped. During discharging of battery, it is equally important to know the state of charge in order to protect the battery from harmful deep discharge.
How does state of charge determination work?
Algorithm for determining a batterys state of charge is a combination of various methods which ensure that the SOC is calculated accurately and reliable or stable values are delivered over a long period of time. The battery voltage and its currents and the temperature are constantly measured as accurately as possible by the solar charge controller. The charge controller estimates the state of charge on the basis of experience values. At the same time the charge controller also monitors the behavior of the battery and adjusts various parameters to the current system.
Which Steca charge controller carries the optimized algorithm?
Steca product range is divided into two categories:
a) One is optimized for use in simple applications and equipped with minimum necessary features.
b) The other one is designed with good communication interface for the user and have optimized battery maintenance features.
