The valve-controlled sealed lead-acid battery is a complex electrochemical system. In the usual backup application, in addition to the main electrochemical reaction during the charge and discharge process, other side reactions are carried out all the time inside the battery. For example, the corrosion process of positive plate grid has always been going on, and the self-discharge caused by positive oxygen evolution and negative hydrogen evolution has always existed.

It is precisely because of the characteristics of the complex Vida battery of the valve-controlled sealed lead-acid battery, the state of the battery in the early stage of operation often does not reach its relative stable state, and some of its commonly used parameters such as floating charge voltage and internal resistance fully reflect this objective law.

1. Floating charging voltage

weida

The stability of the floating charge voltage needs to run for a certain period of time, usually taking 3 to 6 months to reach a stable state. It’s the same reason a new car takes a while to get used to.

In the actual operation of the battery pack, the charger does not control the charging of each battery separately, but controls the charging voltage of the whole battery. If the floating charging voltage of a single unit is 2.25V/2V (13.50V for a 12V battery), set the battery voltage of the 24 batteries of the communication power supply to 24 x 2.25=54V. For 240 UPS batteries, set the battery voltage to 240 x 2.25=540V. At this time, the problem arises – due to the non-consistency of materials and processes in the production process of the new battery, resulting in the non-consistency of the performance parameters of the single battery, and each single battery does not charge according to the ideal set floating charge voltage (2.25V/2V single)! The actual charging voltage of a single battery is usually between 2.20~2.30V/2V single (13.2~13.8V for a 12V battery), so the whole set of battery floating charging voltage shows a large dispersion at the beginning. This state will be significantly improved only after the battery has been charged for a period of time, that is, after the internal state of each battery gradually becomes stable.

The change of floating charge voltage of a new 2V500Ah battery pack at the initial stage of use shows that the floating charge voltage of each cell gradually tends to be consistent after 3 months of operation, and the consistency is very good after 6 months of operation.