It's no secret that over time, the capacity of rechargeable batteries becomes less, and they can no longer give the device the amount of current that they could have given before. In this regard, many users often have a question about how to measure the capacity of the battery, or rather, how to find out the indicator of its residual potential, with which it is possible to understand whether the battery will need to be replaced in the nearest future.
If we proceed from the concept that the capacity indicator is the amount of energy or current given off by the battery over a certain period of time, it simply will not work. If we are talking about how to find out the real capacity of the battery in the form of finger-type batteries, here you will first have to measure the current, and then use some simple calculations - in order for the indicator to be as accurate as possible. As for any Android-based mobile phone, using a small USB tester.
Simple check of the battery capacity with a USB tester with subsequent clarification
The USB tester for measuring battery capacity has a very rich functionality - it measures the battery capacity of a tablet, smartphone,. Based on what this device shows, you can get an idea about the deterioration of the batteries: is it worth changing the battery, or you need to purchase a new device.
With just one control button, you can measure various indicators, including the capacity of the battery of a device. The button switches the tester memory cells and operating modes. If the connected device has a sufficient voltage level, the tester turns on.
The meter displays the battery capacity indicator, as a rule, in the lower left corner. The accuracy of measurements by the tester is not one hundred percent , and therefore it is recommended to use a simple mathematical formula based on the following example.
Let's say you have a certain device (phone, power bank or tablet), which, being completely discharged, was charged in a period of time equal to 3 hours. If, for the sake of curiosity, you measured the current with a tester, and its indicator was, for example, 1.15 A, the real capacity of the battery of your device is calculated by multiplying these two numbers between themselves. 1.15 amperes is 1150 milliamperes, multiply this number by 3 and get 3450 mAh. This is how the real capacity is measured. If on your device the "capacity" of the current is indicated by the manufacturer several times more than the actual one, this is just a standard advertising move, which should not be believed.
How to determine the capacity of batteries with a multimeter
The battery capacity itself cannot be determined with a multimeter. To be more precise, this device will help in determining the actual capacity indicators.
In order to find out the capacity of the 18650 battery, as well as other batteries, the so-called "smart chargers" are used. But their cost is quite high. It is not worth buying such chargers just to determine the capacity of a couple of batteries. This indicator can be easily determined by the usual calculation method with the preliminary use of a multimeter. However, in the calculations, certain subtleties must be observed.
Checking the battery capacity indicator with a multimeter is not just measuring its real indicator, the calculations of which are made using elementary mathematical calculations. It is imperative to measure the level of current given by the battery (any battery) and calculate the exact amount of time during which the battery could continuously and efficiently produce the return of electrochemical energy. It is important to remember that all measurements will not be 100% accurate. But they are the best ones that reflect the true essence of the matter.
They have their own scale of categories. It shows how much U depends on the charge indicator. You need to know: it is on the voltage level that the indicator of the current passing through the resistance depends. In order for this dependence not to affect the measurements, an additional device should be assembled - linear current regulator (2.7-3 volts).
Using a linear regulator
Using this stabilizer, set the current indicator by calculating it from the U 2.7 volt battery. Then, using the U stabilizer, connect any resistor device (it can be made by yourself or purchased from the online store). Measure the current that flows through the circuit and set a stopwatch. Next, we periodically check and monitor the voltage at the battery terminals. When it reaches numbers 2.7 volts, the stopwatch will need to be turned off quickly and recorded the time received.
So how do you measure the capacity of an 18650 battery and other chemical current sources? Real indicator mwe deduce by producing the multiplication of the indicator of the current flowing through the circuit by resistance, by the same time (in hours) that was originally spent ... This is the most accurate measurement of capacitance. In the absence of technical capabilities, it will be more difficult to design a voltage stabilizer, it will be more difficult to carry out calculations and measurements. Try to find a way out of the situation using a variable resistor.
Using a variable resistor
In order to conduct a quality test for capacity, you can use a smaller battery. For example, 14500, the actual capacity of which is 300 mAh. Let's take a variable resistor of 100 ohms. An important point: if a DC resistor is used, the process will be complicated by the fact that it will be necessary to often record the results of its readings and carry out calculations of the spent capacitance for certain sections of the scale .
It is possible to average the indicators as much as possible, focusing on the "arithmetic mean" number of current in the calculation. In order to understand how to measure the battery capacity, it is recommended to use a variable resistor with a metered decrease in the resistance indicator for the entire time that the battery is discharged. It is important that the current level is approximately the same throughout the entire process.
Now switch the multimeter to the voltmeter position (measure U) and measure U at the terminals of your battery. Let's say it has an incomplete charge level, say 4 volts. Then discharge it by applying a current of 450-500 milliamps, from time to time lowering the resistance level and controlling the voltage. When it drops to 2.7 volts, turn off the stopwatch. In order to completely discharge the battery with 500mA current , it takes about half an hour, more precisely, 25 minutes... Now let's multiply this current by the amount of time measured in hours. So, the real capacity indicator is 200 mAh.
Thus, it becomes clear how to find out the battery capacity by applying the most accurate method - not just by measurements, but by mathematical calculations that can most accurately reflect the actual state of the battery and help the user navigate what potential it has in reality.
Each car owner asks himself what device is needed to measure the battery capacity. Measurement of this value is often carried out during the passage of scheduled maintenance, but it will be useful to learn how to determine it yourself.
Battery capacity meter
Battery capacity is a parameter that determines the amount of energy given off by the battery at a given voltage per hour. It is measured in A / h (Ampere per hour), and depends on which is determined by a special device - a hydrometer. When buying a new battery, the manufacturer indicates all technical parameters on the case. But this value can be determined by yourself. There are special devices and methods for this.
The easiest way is to take a special tester, for example "Pendant". This is a modern device for measuring the capacity of a car battery, as well as its voltage. In this case, you will spend the minimum amount of time and get a reliable result. To check, you need to connect the device to the battery terminals and within a few seconds it will determine not only the capacity, but also the battery voltage and the condition of the plates. However, there are other battery capacities.
First method (classic)
For example, a multimeter can be used as a device for measuring the capacity of a car's battery, but you will not get accurate readings with it. A prerequisite for this method (called the test discharge method) is that the battery is fully charged. First, you need to connect a powerful consumer to the battery (an ordinary 60W light bulb is quite suitable).
After that, it is necessary to assemble a circuit, which consists of a multimeter, a battery, a consumer, and apply a load. If the light bulb does not change its brightness within 2 minutes (otherwise the battery cannot be restored), we take the readings of the device at certain intervals. As soon as the indicator falls below the standard battery voltage (under load it is 12V), it will begin to discharge. Now, knowing the period of time that it took to completely empty the energy reserve and the consumer's load current, it is necessary to multiply these values. The product of these values \u200b\u200bis the actual capacity of the battery. If the obtained values \u200b\u200bdiffer from the passport data downwards, the battery needs to be replaced. This method makes it possible to determine the capacity of any battery. The disadvantage of this method is that it is time consuming.
Method two
You can also use a method in which the battery is discharged through a resistor using a special circuit. Using a stopwatch, we determine the time spent on the discharge. Since energy will be lost at a voltage within 1 Volt, we can easily determine using the formula I \u003d UR, where I is the current strength, U is the voltage, and R is the resistance. In this case, it is necessary to avoid a complete discharge of the battery, using, for example, a special relay.
How to make a device yourself
In the absence of the possibility of acquiring a ready-made device, you can always assemble a device for measuring battery capacity with your own hands.
You can use to determine the degree of charge and capacity of the battery. There are many models of ready-made plugs on sale, but you can assemble it yourself. One of the options is discussed below.
This model uses an extended scale, which achieves high measurement accuracy. There is a built-in load resistor. The scale is divided into two ranges (0-10 V and 10-15 V), which gives an additional reduction in measurement error. The device also has a 3-volt scale and another output of the measuring device, making it possible to check individual battery banks. The 15V scale is achieved by lowering the voltage across the diode and zener diode. The device's current value increases if the voltage value exceeds the open level of the zener diode. When a voltage of wrong polarity is applied, a diode performs a protective function.
In the diagram: R1- transfers the required current to the Zener diode; R2 and R3 are resistors selected for the M3240 microammeter; R4 - defines the width of the narrow range of the scale; R5 - load resistance, switched on by the SB1 toggle switch.
The load current is determined by Ohm's law. The load resistance is taken into account.
A device for measuring the capacity of the AA battery
The capacity of AA batteries is measured in mAh (milliamperes per hour). To measure such batteries, special chargers can be used that determine the current, voltage and capacity of the battery. An example of such a device is the AccuPower IQ3 battery capacity tester, which has a power supply with a voltage range of 100 to 240 volts. To measure, you need to insert the batteries into the device, and the display will show all the necessary parameters.
Determination of capacity using a charger
Also, the capacity can be determined using a conventional charger. Having determined the magnitude of the charge current (it is indicated in the characteristics of the device), it is necessary to fully charge the battery and detect the time spent on this. After, multiplying these two values, we get the approximate capacity.
More accurate readings can be obtained using another method, for which you need a fully charged battery, a stopwatch, a multimeter and a consumer (you can use, for example, a flashlight). We connect the consumer to the battery, and using a multimeter we determine the consumption current (the less it is, the more reliable the results). We note the time during which the flashlight was shining, and the result obtained is multiplied by the current consumption.
Batteries are used in many aspects of a person's daily life: vehicles, power tools, uninterruptible power systems, smartphones, laptops, and more.
General information about battery capacity
The main purpose of testing activities for the state of any type of battery is to find out the capacity of the battery and determine other characteristics. However, existing measuring instruments can only accurately determine the strength of the electric current and the voltage in the storage battery, and also measure the density of the electrolyte substance.
The capacity is measured indirectly according to a method specific for each type of battery, or using a device for measuring the capacity of a battery, which gives only an approximate result.
Important! External factors such as ambient temperature can affect the accuracy of any measurement in a battery.
The only reliable way to determine the capacity of a battery is to completely discharge it for many hours, accompanied by constant fixation of many parameters. But not every person is ready to go through such a long procedure, because short-term measurements may be enough to establish approximate data on the battery capacity.
Methods for determining the capacity of the car battery:
- the traditional method is a control discharge (a long and voluminous process in terms of procedures);
- measurement of the density and level of electrolyte liquid in the car accumulator;
- by exposing the battery to the load plug;
- capacity tester.
Interesting. The capacity of popular lithium-ion, nickel-cadmium and nickel-metal hydride batteries can be measured with the same control discharge (the battery can fail if all the rules are not followed) or by purchasing special USB testers on Chinese trading platforms, the accuracy and correctness of measurements of which are under great a question.
Control discharge
Long term test discharge is a traditional laboratory method for establishing battery capacity. The essence of the method is that a fully charged battery is discharged by exposure to constant electric currents, the strength of which depends on the parameters of the product.
Meanwhile, hourly measurements of the battery discharge and voltage are taken, which are recorded. The capacity of the battery is calculated by the formula: the product of the electric current strength by the elapsed specific time. Such a measurement can take up to a day of constant monitoring of the battery, which is not very convenient for many ordinary people.
Load fork
Load plug - a device for testing the battery using a controlled load, equipped with a voltmeter, load resistor and two test leads. Such devices are of various types: with an analog or digital voltmeter, a simple circuit with one load element or sophisticated devices with several load spirals and an ammeter, there are also load plugs for testing the voltage in individual battery banks.
The essence of the measurements is simple and is described in the instructions for the device. The obtained voltage data must be compared with the following table.
Correspondence table of voltage with battery capacity
Measurement of electrolyte density
You can measure the capacity of the battery components (cans) using a device called a "hydrometer". The essence of the method is that the density of the electrolyte in each battery bank is directly related to its capacitive characteristic.
To measure, it is necessary to open all the lids of the autoaccumulator cans and take electrolyte from each vessel one by one, recording the density data from the device. Further, the density of this substance is compared with the correspondence table of density and capacity.
Correspondence table of electrolyte density and capacity
Measurements using special devices
The idea of \u200b\u200ba load plug has been used and improved in electronic portable devices Kulon, which are designed specifically for testing different spectra of lead-acid batteries.
With such devices, you can quickly measure the voltage, determine the approximate capacity of the battery without resorting to a check discharge, and also save the obtained measurements in the device's memory.
Pendant family devices features:
- powered by a battery from which measurements are taken;
- the complete set of devices includes wires with crocodile pliers, which provides a high-quality clamp of wires on all battery terminals;
- a special method for determining the capacity of the battery, which has no analogues;
- it is recommended to independently calibrate the product on a new battery of a similar type to increase the measurement accuracy (the procedure is described by the manufacturer in the operating instructions).
Important! This capacity tester should only be used to establish the capacity in a battery that is fully charged.
There are also other devices from other manufacturers for the same purposes, the method of determining the battery capacity for which is different from each other. For example, SKAT-T-AUTO instruments, PITE testers, Fluke analyzers, Vencon fixtures. All these devices can be used to directly or indirectly measure various parameters.
Knowing the condition of your battery, namely its capacity, you can avoid unpleasant situations on the road. Also, by reacting in time to the discrepancy between the measured indicators and those declared by the manufacturer, you can revive or extend the life of the battery by taking a variety of measures.
Video
Recently, I started to notice that my smartphone began to discharge faster. The search for the software "devourer" of energy did not bear fruit, so I began to wonder if it was time to replace the battery. But there was no absolute certainty that the reason was in the battery. Therefore, before ordering a new battery, I decided to try to measure the real capacity of the old one. For this, it was decided to assemble a simple battery capacity meter, especially since this idea had been hatched for a long time - there are too many batteries and accumulators around us in our everyday life, and it would be nice to have the opportunity to test them from time to time.
The very idea underlying the operation of the device is extremely simple: there is a charged battery and a load in the form of a resistor, you only need to measure the current, voltage and time during the battery discharge, and from the data obtained, calculate its capacity. In principle, you can get by with a voltmeter and an ammeter, but sitting at the devices for several hours is a dubious pleasure, so it is much easier and more accurate to do this using a data logger. I used the Arduino Uno platform as such a recorder.
1. Scheme
There are no problems with measuring voltage and time in Arduino - there is an ADC, but to measure the current you need a shunt. I got the idea to use the pull-up resistor itself as a shunt. That is, knowing the voltage on it and having previously measured the resistance, we can always calculate the current. Therefore, the simplest version of the circuit will consist only of a load and a battery, connected to the analog input of the Arduino. But it would be nice to provide for a load disconnection when the threshold voltage on the battery is reached (for Li-Ion, this is usually 2.5-3V). Therefore, I provided a relay in the circuit, controlled by digital pin 7 through a transistor. The final version of the circuit is shown below.
I placed all the elements of the circuit on a piece of a breadboard that installs directly on the Uno. As a load, I used a spiral made of nichrome wire 0.5 mm thick with a resistance of about 3 ohms. This gives a calculated value of the discharge current of 0.9-1.2A.
2. Current measurement
As mentioned above, the current is calculated based on the voltage on the coil and its resistance. But it is worth considering that the spiral heats up, and the resistance of nichrome is quite dependent on temperature. To compensate for the error, I simply took the volt-ampere characteristic of the coil using a laboratory power supply and letting it warm up before each measurement. Next, I derived the trendline equation (graph below) in Excel, which gives a fairly accurate i (u) dependence, taking into account heating. It can be seen that the line is not straight.
3. Voltage measurement
Since the accuracy of this tester directly depends on the accuracy of voltage measurement, I decided to pay special attention to this. Other articles have repeatedly mentioned the method that allows you to most accurately measure voltage with Atmega controllers. I will repeat only briefly - the point is to determine the internal reference voltage by means of the controller itself. I used the materials in this article.
4. Program
The code is not complicated:
Program text
#define A_PIN 1 #define NUM_READS 100 #define pinRelay 7 const float typVbg \u003d 1.095; // 1.0 - 1.2 float Voff \u003d 2.5; // turn-off voltage float I; float cap \u003d 0; float V; float Vcc; float Wh \u003d 0; unsigned long prevMillis; unsigned long testStart; void setup () (Serial.begin (9600); pinMode (pinRelay, OUTPUT); Serial.println ("Press any key to start the test ..."); while (Serial.available () \u003d\u003d 0) () Serial.println ("Test is launched ..."); Serial.print ("s"); Serial.print (""); Serial.print ("V"); Serial.print (""); Serial. print ("mA"); Serial.print (""); Serial.print ("mAh"); Serial.print (""); Serial.print ("Wh"); Serial.print (""); Serial .println ("Vcc"); digitalWrite (pinRelay, HIGH); testStart \u003d millis (); prevMillis \u003d millis ();) void loop () (Vcc \u003d readVcc (); // read the reference voltage V \u003d (readAnalog (A_PIN ) * Vcc) / 1023.000; // reading the battery voltage if (V\u003e 0.01) I \u003d -13.1 * V * V + 344.3 * V + 23.2; // calculating the current from the I – V characteristic of the spiral else I \u003d 0; cap + \u003d (I * (millis () - prevMillis) / 3600000); // calculation of the battery capacity in mAh Wh + \u003d I * V * (millis () - prevMillis) / 3600000000; // calculation of the battery capacity in Wh prevMillis \u003d millis (); sendData (); // sending data to the serial port if (V< Voff) { //выключение нагрузки при достижении порогового напряжения
digitalWrite(pinRelay, LOW);
Serial.println("Test is done");
while (2 > 1) ())) void sendData () (Serial.print ((millis () - testStart) / 1000); Serial.print (""); Serial.print (V, 3); Serial.print ("") ; Serial.print (I, 1); Serial.print (""); Serial.print (cap, 0); Serial.print (""); Serial.print (Wh, 2); Serial.print ("" ); Serial.println (Vcc, 3);) float readAnalog (int pin) (// read multiple values \u200b\u200band sort them to take the mode int sortedValues; for (int i \u003d 0; i< NUM_READS; i++) {
delay(25);
int value = analogRead(pin);
int j;
if (value < sortedValues || i == 0) {
j = 0; //insert at first position
}
else {
for (j = 1; j < i; j++) {
if (sortedValues <= value && sortedValues[j] >\u003d value) (// j is insert position break;))) for (int k \u003d i; k\u003e< (NUM_READS / 2 + 5); i++) {
returnval += sortedValues[i];
}
return returnval / 10;
}
float readVcc() {
// read multiple values and sort them to take the mode
float sortedValues;
for (int i = 0; i < NUM_READS; i++) {
float tmp = 0.0;
ADMUX = _BV(REFS0) | _BV(MUX3) | _BV(MUX2) | _BV(MUX1);
ADCSRA |= _BV(ADSC); // Start conversion
delay(25);
while (bit_is_set(ADCSRA, ADSC)); // measuring
uint8_t low = ADCL; // must read ADCL first - it then locks ADCH
uint8_t high = ADCH; // unlocks both
tmp = (high << 8) | low;
float value = (typVbg * 1023.0) / tmp;
int j;
if (value < sortedValues || i == 0) {
j = 0; //insert at first position
}
else {
for (j = 1; j < i; j++) {
if (sortedValues <= value && sortedValues[j] >\u003d value) (// j is insert position break;))) for (int k \u003d i; k\u003e j; k--) (// move all values \u200b\u200bhigher than current reading up one position sortedValues \u200b\u200b[k] \u003d sortedValues; ) sortedValues \u200b\u200b[j] \u003d value; // insert current reading) // return scaled mode of 10 values \u200b\u200bfloat returnval \u003d 0; for (int i \u003d NUM_READS / 2 - 5; i< (NUM_READS / 2 + 5); i++) {
returnval += sortedValues[i];
}
return returnval / 10;
}
Every 5 seconds, time, battery voltage, discharge current, current capacity in mAh and Wh, and supply voltage are transmitted to the serial port. The current is calculated using the function obtained in item 2. When the threshold voltage Voff is reached, the test stops.
The only interesting point in the code, in my opinion, is the use of a digital filter. The fact is that when reading the voltage, the values \u200b\u200binevitably "dance" up and down. At first I tried to reduce this effect by simply taking 100 measurements in 5 seconds and taking the average. But the result still didn't satisfy me. While searching, I came across such a software filter. It works in a similar way, but instead of averaging, it sorts all 100 measurement values \u200b\u200bin ascending order, selects the center 10 and calculates the average of them. The result impressed me - the fluctuations of the measurements completely stopped. I decided to use it to measure the internal reference voltage as well (readVcc function in the code).
5. Results
The data from the serial port monitor is imported into Excel in a few clicks and looks like this:
In the case of my Nexus 5, the stated capacity of the BL-T9 battery is 2300 mAh. Measured by me - 2040 mAh with a discharge of up to 2.5 V. In reality, the controller hardly allows the battery to sit down to such a low voltage, most likely the threshold value is 3V. The capacity in this case is 1960 mAh. One and a half years of phone service led to a drop in capacity of about 15%. It was decided to postpone the purchase of a new battery.
Several other Li-Ion batteries have already been discharged with this tester. The results look very realistic. The measured capacity of new batteries coincides with the declared one with a deviation of less than 2%.
This tester is also suitable for metal hydride AA batteries. The discharge current in this case will be about 400 mA.
A modular version of a visual and accurate meter for ampere-hours of batteries, assembled from computer waste at minimal cost.
This is my response to the article.
A little prelude ...
Under my patronage is a park of 70 computers, different years of release and state. Naturally, an overwhelming number of uninterruptible power supplies are available (in the text - UPS). The organization is budgetary, of course, they don't give money, like - do what you want, but everything should work. After short tests with a load in the form of a 150-watt light bulb, I found that 70% of UPSs do not hold the load for more than 1 minute, APC UPSs sin with switching relay contacts (it goes to the battery, buzzes and beeps, and the output is completely zero). Of course, no one gave me all the UPSs to check at once. The solution turned out to be simple: once in half a year - a year I took the computers for cleaning, lubrication, and at the same time the UPS for the test and inspection of the giblets.
Of course, UPSs of different brands and capacities (there are old men for 600 watts of 1992 release, the battery died this fall, before that I did resuscitation 4 years ago). If someone is not in the know, in household and office UPS, batteries of different types, housings, voltages and capacities are used. A typical representative is the GP1272F2 (12 Volt, 7 A / h). But they also come across at 6V - 4.5 A / h.
Battery prices often exceed half the price of a new UPS. Moreover, dead batteries accumulate in the office (in which I work part-time). The question arose, what is the real capacity before and after lifting from the trash can, how many minutes of operation can be expected from the UPS. And then an article caught my eye I. Nechaeva In the magazine "Radio" 2/2009 about a similar meter.
Of course, I didn’t like some moments, I’m such a bastard.
And so let's start with ...
This is the original diagram from the article.
TTX: discharge current 50, 250, 500 mA, cut-off voltage 2.5-27.5 Volts.
I will list, what didn’t like: the maximum discharge current is only 0.5A (and it is not interesting to wait until 7 Ah is discharged), the cut-off range is too wide and it is easy to knock it down, all the current flows through the button to start, the current stabilizer on the field controller for the LED is overkill, the diode in the control output increases the required drop on current resistors is up to 1.8V and in case of breakdown, 317 skids.
About discharge current: in batteries, it happens that the active mass is, as it were, sealed in a spread (not to be confused with sulfation), while the mobility of the electrolyte decreases and if it is discharged with a low current, it can give up its capacity completely, and when installed in a UPS, the test will not pass. Well then, you need to discharge it with a small current and charge it, i.e. to treat.
The modularity of what I have done is good because you can make 2 or more discharge modules (you can switch 1 and switch current resistors) of different power or even type and 2 cut-off devices for 6 and 12-volt batteries, or 1 with a switch.
Photos of my meter:
We see: cut-off unit, current load, Chinese walkers.
I repeat, I work as a sysadmin, sometimes I fix motherboards, so there is some kind of dead iron slide.
I'll start in the reverse order: the walkers are slightly modified so that they can run when powered from 1.5 to 25 volts.
Walker modification scheme:
1117 pulled from a dead motherboard.
The 2K resistor is the minimum load for the regulator.
accordingly the scheme:
This is 2 amperes. Since R1 turned out to be more than 0.75 ohms, it was necessary to add 2 resistances (this is R3, two in one in the photo) so that the current was 2 amperes. If someone has not noticed, there are no gaskets between the micro with a transistor on the radiator. You can of course use another circuit, such as in radio 3/2007 page 34, just add the reference voltage.
Current and thermal protection in 317 (real) is.
And the scariest part is the cutter.
Super 3D montage, but only 3 cm cubic, on the seal will be much larger. Polevik, if on 6V battery, then it is very desirable with logical control.
This part almost does not differ from the original one, the start button has been moved from the drain-source to the collector-emitter, the variable is replaced with a fixed divider, a Chinese super-bright LED through a resistor.
Possible variations:the upper arm (according to the original scheme, this is R4), replace it with a resistance + variable, thus limiting the setting range (required when the discharge current is comparable to the battery capacity); other ideas are possible.
For formulas Uref \u003d 2.5v for normal 431, and for 431L it is equal to 1.25v.
Fixed Voltage Shutter:
Formula for calculation: Uotc \u003d Uref (1 + R4 / R5)
or R5 \u003d (Uotc-Uref) / (Uref * R4)
Adjustable Voltage Cutoff:
Formula for calculation: Uotc \u003d Uref (1+ (R4 + R6) / R5)
or R5 \u003d (Uotc- Uref) / (Uref * (R4 + R6))
But here it is necessary to count from a variable, on it, at a discharge of 0.1s, (Udelta) 1.15v for 6v akb and 2.30v for 12v akb should fall.
Therefore, the formulas are transformed and the calculation is somewhat different.
Umin look in the table below.
R5 \u003d Uref * R6 / Udelta
R4 \u003d ((Umin -Uref) * R5) / Umin
