Introduction
To ensure that the equipment unattended (such as absenteeism, etc.), even after the start, often to join the battery as backup power. In the grid after the beginning of the power equipment of the battery. At this point, you must set the battery protection circuit discharge. The simplest protection is to establish a protection threshold battery voltage when the battery voltage to this threshold, the automatic disconnection of the circuit, stops feeding the load. However, the load is disconnected, the voltage across the battery to rise rapidly above the threshold voltage, circuit re-open so that the battery was the power load, then repeat the “One Off One Off a look at “oscillation process, until the battery is completely discharged. This is the battery life will be a great influence, even damage the battery. Therefore, we must develop a function with a hysteresis circuit automatic protection. Dell Inspiron 1501 battery Dell Inspiron 9300 battery
Currently on the market a few chips ready-made battery protection can be used, but these chips typically used in lithium battery voltage level of protection and more focused around 5V. In some applications of high-voltage battery, for example, 10V to 50V supply system can be applied. This article provides a simple and effective hysteresis area with battery protection circuit, set the two threshold voltages, to avoid oscillations, but also because these two thresholds can be set to any resistance, it can be applied to hundreds of volts battery system.
1 Principle of Protection
Assume that the battery voltage Ubat, the only system to establish a teaching hospital voltage protection threshold. Then, when the battery voltage is lower than the UHC, the output of low comparator circuit, the load is disconnected. However, the removal of the load, the voltage across the battery quickly grew to more than UHC, the comparator output is still high, the load must be access to the training of the oscillation. Dell Inspiron Mini 10 battery Dell XPS M1210 battery
However, if the circuit is located in the comparison of two threshold voltages: UTHH and UTHL (UTHH> UTHL), you can create a zone of hysteresis. When the battery voltage is increased from low to UTHH, the comparator output is high, open the electronic switch, power to the load when the battery voltage down to UTHL, the comparator output low, disconnecting the load. Although this time the battery voltage to rise rapidly over UTHL, but fail to UTHH, therefore, the comparator output is still low, the load is disconnected until the battery is charged, the voltage can be increased to more than UTHH new connected load. This avoids the oscillation circuit to protect the load and battery. Dell Inspiron B130 battery Dell Latitude D820 battery
Although the vast majority of comparison circuits both with hysteresis, but most often within the circuit voltage hysteresis hysteresis (ie a UTHH UTHL) than 5mV to 10mV, simply can not be used to protect over discharge. Figure 2 (a) the use of feedback comparator circuit output voltage adjusts automatically from the reference value, the input voltage at different time intervals were compared and the threshold voltage conversion UTHH UTHL between the two. Figure 2 (b) shows the output when the input signal changes in response to the use of the comparator output signal to drive the electronic switch, where production is high, the battery is access systems, where the output is low, the load is disconnected. dell inspiron e1505 battery dell inspiron e1705 battery
Since then, even if the battery voltage is below UTHH, but as always more than UTHL, the battery has been at the output state after the voltage UTHL, production is low, the load is disconnected. Meanwhile, in a threshold VT, the threshold voltage re-translated into UTHH, although the removal of the load to increase the voltage of the battery terminal, but still below UTHH, the burden will not be returned. This effectively protects the battery, extended battery life. dell inspiron b130 battery dell inspiron e1405 battery