Equalization Charge
A controlled overcharge applied for a short time in flooded lead-acid batteries to dissolve the sulphate build-up on the plates and close the difference between cells. It is done at a voltage above the normal absorption voltage, for the duration set by the manufacturer, and it is not applied to lithium batteries.
On lead-acid plates left undercharged for a long time, lead sulphate crystals harden and do not dissolve at the normal charge voltage. Equalization charging deliberately raises the voltage to break up these crystals and at the same time stirs up the stratification by boiling the electrolyte.
The process is risky and has conditions. It is applied only to flooded (serviceable) lead-acid batteries; the cell caps must be openable and it must be possible to top up with distilled water afterwards. The area must be well ventilated, because the hydrogen released is explosive. Sensitive 12 V loads must be disconnected so that they are not affected by the raised voltage during the process.
On AGM and gel batteries most manufacturers either prohibit equalization entirely or allow it at a very limited voltage; water lost in a sealed case cannot be replaced. In LiFePO4 the concept is invalid: there the cell difference is balanced by the BMS and overvoltage is direct cell damage. Do not run this function without knowing which chemistry is in your RV.
Context in which this term is used: RV automatic levelling guide