Here is a very useful project of low battery voltage cutoff or disconnect circuit. Rechargeable batteries deliver very good performance and life if we take care of them. There are many things which can be done to take proper care and protect your rechargeable batteries which are not over charge.
When the batteries get fully discharge frequently then their life will get shorten and become dead in few weeks. Therefore it is better to disconnect your battery from the load when your battery become weak or require recharging. But it is very difficult to check and disconnect from the load every time they require charging. But the circuit shown here will do this job very efficiently by automatically monitoring the voltage of the battery and disconnect the battery from the load on the preset low voltage level of the battery.
The circuit is very simple to build and using few components. The heart of the circuit is a TL operational amplifier IC that is connected in comparator mode here. The 10K variable resistor is used to adjust the desired voltage level on which you want to deactivate the relay or disconnect the load from the battery. A 2N transistor is connected at the output of the IC to drive the relay. The 5. The circuit can be used with any type of batteries for example 12V, 9V, 6V, 5V etc.
Only you have to change the 5. For example if you want to use the circuit with 6V battery then simply change the zener diode value to 3. Electronics Beginner Guide Tutorials. Audio Circuits. Power Supply Circuits. Battery Chargers. Telephone Circuits. FM Transmitter Circuits.
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Please note the latest update before constructing the circuit. R ecently in a repeaters owner's discussion group repeater repeater. I made the rash comment that the aforementioned circuit was overly complex and that one could achieve the same ends with a single NE IC and a dozen passive components. I was immediately challenged to show this simplified circuit.
The following is the result. It does have a few more than a dozen passive parts but still makes a much simpler circuit than the QST article. I hope that it is useful to some folks. It contains two voltage comparators with an internal reference, an R-S FlipFlop and a "totem-pole" type output circuit capable of sourcing or sinking up to ma.
All of these subcircuits are used to advantage in this battery disconnect circuit. When the battery voltage goes below this setpoint, the output voltage on pin 3 will go high. Another pot is connected across the battery with its wiper to pin 6. When the battery exceeds this setpoint, the output pin will go low.
All that is left to enable the disconnect circuit is a relay driver that will turn on the relay when the output is low and release it when the output is high. The detailed circuit has some refinements on the basic that make for easier adjustment and more stable operation. U1 NE needs a regulated supply voltage to supply the internal voltage divider references that control the input voltage comparators connected to pins 2 and 6.
VR1, a 7. R9 resistance is chosen so that the zener voltage will be maintained down to about 10v input supply or below. C3 filters the regulated voltage. Should the supply voltage be reversed, the zener diode will clamp the voltage at The fixed resistors are chosen so that the pots cover the expected adjustment range volts for R2 and volts for R5 and make the adjustment easier.
R7 and C1 provide some time delay for the ON adjustment when the monitored voltage abruptly changes. Similarly R8 and C2 provide a time delay for the OFF setpoint for abrupt changes in the monitored voltage. These components have little effect on gradual changes in the monitored voltage but the time delay from abrupt changes depends on the amount of change and how far below the OFF setpoint the lower voltage is.
Since any leakage current in capacitors C1 and C2 will upset the setpoints, they are chosen for minimum leakage. C1 and C2 capacitors in the time delay circuit also serve another purpose. Conventionally these capacitors would be connected to ground but by connecting them between the input and V CC U1 regulated supply voltage the time delay effect is the same and there is an added bonus. When the circuit is powered up, pins 2 and 6 will be forced high momentarily by the charging of C1 and C2 capacitors.
This guarantees that the circuit will power up in the "ON" position which is essential for proper operation. If the capacitors were connected to ground, it would power up in the OFF position which would be very undesirable. U1 pin 5 is connected to one of the internal reference voltage divider taps and C4 filters this point to reduce effects of noise on the power supply.
U1 output pin 3 will have a low voltage when the circuit is "ON" and a high near V CC when it has tripped off. Q1 inverts this action so that the "ON" state is high. Q1 and R11 also level shifts the high voltage state to the volt supply level rather than the regulated V CC. This reduces the current required from the regulated supply.The following post describes a simple low battery indicator circuit by using just two inexpensive NPN transistors.
The main feature of this circuit is its very low stand by current consumption. We have so far seen how to make a low battery indicator circuits using a IC and a ICwhich are no doubt outstanding with their abilities of detecting and indicating low battery voltage thresholds. The main advantage of the proposed two transistor low battery indicator circuit is its very low current consumption compared to the IC counterparts which consume relatively higher currents.
Thus the present circuit becomes more efficient especially in cases where stand by current consumption tend to become an issue, example suppose in units which depend on low current battery supplies such as a 9V PP3 battery. Another advantage of this circuit is it's ability to work even at voltages around 1. As shown in the following circuit diagram, the two transistors are configured as voltage sensor and inverter.
The first transistor on the left senses the threshold voltage level as per the setting of the 47K preset. As soon as the battery voltage falls below the set threshold level, the left transistor is no longer able to conduct. The above circuit was successfully built and installed by Mr.Low voltage cut-OFF BMS battery protection - How to make
Allan in his paranormal depletion detector unit. The following video presents the implementation results:. Referring to the above diagram, the low battery indicator is formed by the two NPN transistors, while the additional BC and the relay are used for cutting OFF the battery from the load when it reaches the lower threshold, in this state the relay connects the battery to the available charging input.
However when the battery is in its normal state the relay connects the battery with the load and allows the load to operate through battery power. One drawback of the above design could be the chattering of the relay at the threshold voltage levels, due to the battery voltage dropping immediately during the relay changeover process. This can be prevented by adding a uF at the base of the middle BC In order to rectify this, a hysteresis effect will need to be introduced which can be accomplished through a feedback resistor between the collector of the BC and the middle BC transistor.
The two resistors, one at the base of BC and the other at the collector of BC decide the other threshold of the relay changeover, meaning the full charge cut off threshold of the battery. Here, the values are arbitrarily selected, for accurate results these values will need to be optimized with some trial and error.
48V Solar Battery Charger Circuit with High/Low Cut-off
If you have any circuit related query, you may interact through comments, I'll be most happy to help! Your email:. Also, I am charging the battery from a solar panel via charge controller. So during night time no means to charge the battery. We store them at 7. I was wondering if this circuit would allow us to discharge the battery with a 5 amp load, and then have this circuit disconnect the battery at 7.
I selected cut off voltage How can I avoid this issue?This circuit protects the costly equipment like TVs, air conditioners, Refrigerators, etc.
If the supplied voltage is abnormal High or low then the circuit automatically turns of the load. This circuit also produces sound when main power resumes. Generally voltage stabilizers are used in this type of applications to maintain constant AC voltage.
The frequent energization or de-energization of relays leads to the shortening the life time of appliances and the stabilizer itself. Hence it is better to use this project in order to control the appliances instead of costly stabilizers. When supply voltage is high, the DC voltage at the cathode of zener diode D4 becomes greater than 5.
As a result, transistor Q1 is in ON and transistor Q2 gets switched off. Under low supply voltage condition, transistor Q1 switches to ON condition and as a result transistor Q2 switches off, making the load OFF.
When normal AC supply voltage is applied, the DC voltage at the cathode of zener diode D4 is less than 5. When supply is resumed after a break, timer IC goes low and this triggers the timer IC. Thus the relay switches off the load. In this circuit, timer is configured to operate in monostable mode. In this circuit, pin4 and pin8 are shorted to avoid sudden resets. The pulse width of the timer output signal is about 10 seconds.
This output signal drives the speaker. Speaker gives melodious sound when power is resumed because of UM66 IC. Red LED is used for power indication. Here zener diode D4 along with transistor Q1 is used for comparing the input voltage. Transistor Q2 switches the load based on the output of transistor Q1. Diodes D1 and D2 are used for rectification purpose.
Capacitor C1 filters the input AC ripples. Thank you for providing us a good way of knowledge. High and low voltage cutoff circuit is working. Your email address will not be published. Table of Contents. Comments In this circuit i cant able to understand why V1 vsine is connected to relay and what is vsine.The figure shows a very simple circuit set up which performs the function of an overload sensor and also as an under voltage detector. In both the cases the circuit trips the relay for protecting the output under the above conditions.
Transistor T1 is wired as a current sensorwhere the resistor R1 forms the current to voltage converter. The battery voltage has to pass through R1 before reaching the load at the output and therefore the current passing through it is proportionately transformed into voltage across it.
The conduction of T1 grounds the base of T2 which gets immediately switched Off. The relay is also consequently switched OFF and so is the load. T1 thus takes care of the over load and short circuit conditions. Transistor T2 has been introduced for responding to T1's actions and also for detecting low voltage conditions.
When the battery voltage falls beyond a certain low voltage threshold, the base current of T2 becomes sufficiently low such that it's no longer able to hold the relay into conduction and switches it OFF and also the load.
This implies that the battery current from the right side has to pass through R1 before reaching the inverter, enabling the sensing circuit around R1 to sense a possible over current or overload situation. The above shown circuit will not initiate unless the relay is actuated manually through a push switch as shown below:.
If you have any circuit related query, you may interact through comments, I'll be most happy to help! Your email:. Sir, I have been having this constant problem with repair of Indian inverters. And it has to do with overload, no load, etc fault. Please, an you give me a clue as to how to tackle this issue. I have no idea where to start. Robert, all inverters have different board configuration and component settings, so it can be difficult to judge their faults commonly….
Hi sir please i my circuit diagram and if i built it blow the mosfet and if i can send my circuit diagram to check it if there is any problem then please you help me.
Thanks sir. Thank you. Hi Saeed, if it is a ferrite based design then it can be difficult to troubleshoot for me, because ferrite trafos require strict calculations for the winding, and a wrongly built trafo can cause instant burning of the devices.Add the following snippet to your HTML:.
Project tutorial by Jean-Michel Julien. This project came to life when I received an old fishing sonar from a friend my dad. The sonar supply voltage is rated from 10V to 17V. After testing with a power source, I found out that it kept working with a voltage as low as 7. It consume between mA and mA under normal conditions. These battery packs have a usable voltage of I thought that it would be a good idea to use some of my old LiPo battery packs to power the sonar, as the voltage of a 3 cell pack is in the perfect voltage range of the supply.
And also, it is way lighter to carry than a lead-acid or 8 D batteries. After a life of intense usage helicopter flying these packs loose their punch, however they are still very capable for a less demanding usage.
The idea is to extend the life of those battery packs before destroying them. One of the issues with LiPo packs is that they do not handle over discharging very well; they can even self ignite under bad conditions. Especially if you try to recharge them when they are over discharged.
In this case, the sonar would only shutdown at a little under 8V which is too low for our pack 9V. So this is where this project comes to life; make a circuit to automatically cutoff the battery pack at a specific low voltage. The main concern here is to make sure not to over discharge the battery pack since after that it is quite hazardous to recharge it.
In my case I want to totally disconnect the battery. For the switching of the load, with the requirement of allowing a good amount of current supply, a relay was a good choice since it would isolate the application circuit current draw from the monitoring one. However, it takes quite a lot of current to keep a relay energized and this was also one of my requirement minimal current draw during usage. So the solution came with a latching relay.
This less common type of relay will keep its last position even after the inductor is de-energized. My whole design is based on the latching relay.
So I concentrated my build around that component. I chose an Arduino Pro Mini for this project as it is very small, and has a low power consumption since there is no usb-rs conversion chip on that board you need a fdti cable or interface to program the board.
I also removed the power LED and the onboard voltage regulator to minimize the power consumption. Without the and the voltage regulator chip, it is just the mcu that will consume power. Another factor that drove my choice is that I have a bunch of them laying around. The monitoring circuit is made of a voltage regulator ams ; I used an external regulator because the LiPo pack voltage when full is too high for the regulator on the Arduino Mini board.In this video I will show you how to build a simple lithium battery protection circuit, so you can power your homemade projects without ever worrying about over discharging your battery.
Did you use this instructable in your classroom? Add a Teacher Note to share how you incorporated it into your lesson. Question 1 year ago. Question 2 years ago on Introduction.
That relay only handles 8A. Would this circuit still be suitable for RC projects such as drones that can routinely spike to hundreds of Amps current?
I'm hoping to make something like this, could you help me with it? I need a circuit that'll monitor voltage of a battery 3S LiPo, "normal voltage" of Could you possibly assist with this?
I am unable to get a hold of the 5v in Canada without crazy shipping cost or is there another brand I can substitute. And what kind of push button do you use, as I guess it should be a momentary switch, but it looks like a latching switch?
I've wanted a low voltage alarm for my rc planes, but never sprung to buy one. I'm guessing this could be modified fairly simply to trip a loud buzzer, rather than simply cut off power? Reply 4 years ago. To turn the circuit off, wouldn't it be more simple to add a toggle switch between one of the balanced connectors and the monitor, so that when off, it would read 0v and trigger the "alarm" which in turn triggers the relay?
More by the author:. About: Hello! I'm Matt and I love making things.
NE555 Low Voltage Battery Disconnect Circuit
I'm always thinking of new ideas and how to make them as awesome as possible, always with a mind to share the process online.
Take a look at my profile and see if th Add Teacher Note. Did you make this project? Share it with us! I Made It! Answer Upvote. Reply Upvote. RedBul Fuel 3 years ago. Wow, really great, just what I needed. Could you maybe link to all products used? Is it necessary to use a 82 Ohm resistor or could I use a Ohm one? Very nice! This is a handy item to have. MarcR6 4 years ago on Introduction.