[bill-e]

Since the batteries are the most expensive consumable in a solar system, it is important to protect them. Some of the name brand controllers have 3 stages and some up to 5 stages (Zamp for instance) similar to the better brands of chargers in your RV's power panel..

1. Soft Charge- When batteries suffer an over-discharge, the controller will softly ramps the battery voltage up to 10V for 12V battery, 20V for 24V battery.

2. Bulk Charge-Maximum current charging until batteries rise to Absorption level

3. Absorption Charge-Constant voltage charging and battery is over 85%.

4. Equalization Charge*- Only for WET battery or Calcium battery type, when the battery is deeply drained below 10V, it will automatically run this stage to bring the internal cells as an equal state and fully complement the loss of
capacity. (LiFePO4, LTO, Gel and AGM battery do not run Equalization
charge)

5. Float Charge- Battery is fully charged and maintained at a safe level.
A fully charged Lead acid battery (GEL, AGM, WET battery) has a voltage
of more than 13.6 Volts; A fully charged LiFePO4 or LTO battery has a
voltage level of 13.4V.