Hanfong professional engineers parsing: solar controller can't charge, because it enters into the charging protection mode.
Charge and discharge protection mode has the following four points:
1.The point of direct charge voltage: when charging the battery terminal voltage is higher than the protection value, it should stop charging. Otherwise it will cause of over charging, the battery is damaged.
2. The point of charge control voltage: after direct charge, the battery will be charged and discharged controller for a period of time, and let the voltage drop naturally. When the drop to the "recovery voltage" value, it will enter the state are charged. Why design average charge? When the direct charge is completed, there may be individual battery "backward" (terminal voltage is relatively low) In order to pull these individual molecules back, and make all the battery terminal voltage uniformity, so it is necessary to use high-voltage charge it for a small time.
3.The point of float control voltage: after average charge, the battery will be charged and discharged controller for a period of time, and let the voltage drop naturally. When the drop to "maintenance voltage" point, it will enter the floating state. Currently, we use PWM
(both pulse width modulation) mode, it is similar to "trickle charge". When the battery voltage is low, then to charge power a little by a little, so that the battery temperature continues to rise. This is very good for the battery, because the battery internal temperature on the charge and discharge have a great impact.In fact, PWM mode is mainly to stabilize the battery voltage to design, and reduce the battery charging current by adjusting the pulse width. This is a scientific charge management system. Specifically, at the end of charging, when the remaining capacity (SOC) of the battery is more than 80% , the charging current must be reduced to prevent excessive release of the gas (oxygen, hydrogen and acid gas) due to overcharge.
4.Over-discharge protection termination voltage: It refers to the battery discharge can not be lower than this value. For safety reasons,12V battery over-discharge protection point voltage plus 0.3v as a temperature compensation or control circuit zero drift correction, so that 12V battery over-discharge protection point voltage is: 11.10v, and 24V system over-discharge protection point voltage of 22.20V. At present, many manufacturers are use standard 22.2v (24v system) to charge and discharge controller.