Solar Charge Controller Charge And Discharge Protection

- Jun 04, 2018-

1, direct charge protection point voltage: direct charge is also called emergency charging, is a fast charge, generally when the battery voltage is low when the battery is charged with a large current and relatively high voltage, but there is a control point, also known as protection The point is the value in the above table. When the battery terminal voltage is higher than these protection values during charging, the direct charge should be stopped. Direct-charge protection point voltage is generally also "overcharge protection point" voltage, battery voltage can not be higher than this protection point when charging, otherwise it will cause overcharge, the battery is damaged.

2. Charge control point voltage: After the direct charge is over, the battery is usually left to stand for a period of time to allow the voltage to drop naturally. When it falls to the “recovery voltage” value, it will enter the equal charge state. Why do you want to design all charge? That is, when the direct charge is complete, there may be individual batteries "backward" (the terminal voltage is relatively low), in order to pull these individual molecules back, so that all the battery terminal voltage has a uniform consistency, it is necessary to match the high voltage with moderate The current is recharged for such a small amount of time. It can be seen that the so-called equal charge, that is, "balanced charge." The average charge time should not be too long, usually a few minutes to ten minutes, but the time setting is too long to be harmful. For a small system equipped with a two-battery battery, it is not meaningful. Therefore, street light controllers generally do not have equal charge. There are only two stages.

3. Float control point voltage: After the equalization is completed, the battery is also allowed to stand for a period of time to naturally drop the terminal voltage. When it falls to the “maintenance voltage” point, it enters the floating state. PWM is currently used. (Pulse Width Modulation) mode, similar to "trickle charge" (ie, low-current charging), when the battery voltage is low, it is charged to a point. When it is low, it is charged to one point and one strand is coming in order to prevent the battery temperature from continuing to rise. High, this is very good for the battery, because the internal temperature of the battery has a great influence on the charge and discharge. In fact, the PWM method is mainly designed to stabilize the battery terminal voltage, and the battery charging current is reduced by adjusting the pulse width. This is a very scientific charging management system. Specifically, at the end of charge, when the battery's remaining capacity (SOC) is >80%, the charge current must be reduced to prevent over-exhaustion due to overcharging (oxygen, hydrogen, and sour gas).

4, over discharge protection termination voltage: This is better understood. Battery discharge can not be lower than this value, this is the national standard. Although battery manufacturers also have their own protection parameters (enterprise or line), they still have to move closer to the national standard. It should be noted that, for the sake of safety, generally the 12V battery over-voltage protection point plus 0.3v artificially added as temperature compensation or control circuit zero drift correction, so that the 12V battery over-discharge protection point voltage is: 11.10v, then The over-discharge protection point voltage of the 24V system is 22.20V. At present, many manufacturers producing charge-discharge controllers use the 22.2v (24v system) standard.