![]() Simple 6v battery guard circuit series#Untitled DocumentSpecifications of 8 Series LiFePO4 Batteries Charge & Discharge Guard ShieldApplication:The product could be widely used in the fields of electric vehicles, standby power supply and power supply of military equipment, etc.Main Functions:The product has 5 main functionsover charge, over discharge, over current, short circuits and balancing. Choosing Resistors for NE555 LVD Circuitįor simplicity set one of the resistors in each voltage divider to be 10K:Īll we need to do now is calculate the values of R2 and R4 which will give us the desired disconnect and reconnect voltages – in this example 11.8V and 12.8V respectively, but plug in your own values to meet your own requirements.Discount on Protection Circuit Module For 8 Cells LiFePO4 Battery Pack 30A Working (60A cut-off) and get fast shipping on best promotion today. So, we need to set the resistor values in the voltage dividers so that the trigger pin will see 1.667V when the battery voltage is at the voltage we want to engage the low voltage disconnect, and the threshold pin will see 3.333V when the battery voltage is at the voltage we want to cancel the low voltage disconnect. Therefore the trigger input is waiting to respond to a voltage of less than 1/3 of 5V = 1.667V, and the threshold input is waiting to respond to a voltage of greater than 2/3 of 5V = 3.333V. The LM7805 supplies a fixed 5V to the NE555 chip. (Capacitor C1 is there to prevent noise on the supply line affecting the voltage measurements etc, capacitor C2 helps to keep the voltage from the battery stable, and diode D1 is there to prevent back-EMF from the relay coil damaging the NE555.) Last and most importantly we have two voltage dividers which will output a fixed fraction of the battery voltage to be measured. When the voltage on the threshold input is greater than 2/3 of Vcc, the NE555 output pin 3 goes and stays LOW.Ībove is the schematic for our low voltage disconnect based on the NE555 chip to which a couple of capacitors, an LM7805 voltage regulator, and a relay have been added. When the voltage on the trigger input is less than 1/3 of Vcc, the NE555 output pin 3 goes and stays HIGH. The NE555 has two voltage comparators ( trigger and threshold) which compare the voltage connected to them with the regulated NE555 supply voltage (Vcc). This chip is used primarily to make timers and oscillators, but it can also operate as a bistable latch. In order to achieve this all we need is one integrated circuit – the NE555 timer IC. ![]() disconnect the loads when the battery voltage is below 12.0V and reconnect them only when the battery voltage is above 12.4V. This can be achieved having one voltage threshold to disconnect the loads, and a different voltage threshold to connect the loads – e.g. But, we must include hysteresis to prevent the output flipping on and off rapidly when the battery voltage is at the threshold. All we need to make a low voltage disconnect is something which can measure the voltage of the battery and connect the loads when the battery voltage is above a threshold and disconnect the loads when the battery voltage is below the threshold. ![]()
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