Vehicle on-board voltage indicator, given in this article, is intended for visual monitoring of the voltage of the on-board network of a passenger car. Everyone knows that the normal voltage value available in the vehicle’s on-board network has a positive effect on the service life of the battery, especially in winter. Therefore, in severe frosts, it is advisable to use it to start a car engine.
It should be such that with the engine running well, the generator would be enough for all energy consumers. And at the same time, there should not be too much of it, as this can lead to overcharging the battery.
Description of the vehicle voltage indicator
Optimal voltage of the vehicle's on-board network with a 12V battery, the range is considered to be from 11.7V to 14V. Going beyond these limits is extremely undesirable, since when it drops below 11.7V, the battery suddenly discharges, and when it exceeds 14V, it begins to recharge. You can monitor the vehicle’s on-board network using a simple indicator consisting of two comparators and three LEDs, the diagram of which is given below.
Indicator circuit very simple, the essence of its work is that the current voltage taken from the divider, built on resistors R2, R3, R4, is compared with the reference, built on the zener diode VD1 (5.6V). The optimal voltage is shown by a green LED, a state above 14V is indicated by a red LED, and accordingly a yellow LED indicates a state below 11.7V. The op-amp used in this circuit
For the first time, I was offered to write a review of a product by store representatives; my choice fell on a car USB charger under the iMars brand with two ports and a voltage and current indicator. The final goal was to replace two devices in my father's car - a voltmeter in the cigarette lighter, with which my father controls the battery voltage and the need to charge it in winter, as well as a simple noname phone charger with a maximum current of 500mA.
The manufacturer promises maximum charging current 4.8A (2.4A+2.4A), measuring the voltage of the vehicle's on-board network and the charging current of connected devices. Let's see if we can replace two devices with one and whether the manufacturer's promises will be confirmed further...
The charger was packed in a cardboard box, inside of which was the charger itself. No instructions or anything like that. All inscriptions on the box are in English.
Unboxing
Immediately after receiving the parcel, I decided to test the charger in my father’s car (VAZ 2111) to check if it works. And then the first problem awaited me - the charger did not reach the central contact of the cigarette lighter in this car... I tested it in my Skoda Fabia - charging worked, but it’s somehow not very convenient to carry out tests in the car, so I decided to power the charger at home from the power supply on 12V through the cigarette lighter connector to a cable purchased once on Aliexpress. And then the second problem awaited me - in this connector the charger also did not reach the central contact. The depth of the charger at 39 mm turned out to be too large... So even without starting testing, we can say that the charger is not suitable for all cars and connectors, the maximum depth at which it will work is about 37 mm.
Somehow, using wires and blue electrical tape, I connected the charger to the power supply from the laptop, the charger displayed the value 16.8U. 
Okay, the first simple test is to connect the iPad mini to the charger and it’s charging. The display, voltage and charging current change approximately every 2 seconds. Shows current 2.15A.
Next, you need to check the manufacturer’s statement about the maximum current of 4.8A, but unfortunately I don’t have a USB load, which many here use to test chargers, so I came up with the idea of using car incandescent lamps as a load (warm lamp load, in the literal sense of the word ).
I connected a 12V H4 car lamp to the charger via a USB tester - the charger displays a current of 2.32A, the tester shows a little less, 2.14A
Let's continue testing, I'll try to connect the phone to another port along with the lamp. Since I don’t have a second USB tester, I use a multimeter to measure the lamp current, and a tester for the phone. And here’s a surprise: the phone shows that it is charging, but the tester displays a very small current, only 0.09A.
Let's try to load the charger more. I connect an H4 light bulb to one port, the same as in the first experiment, and to the second - a 24V auto lamp - it has more resistance, the current will be less.
Result - the charger displays 3.03A, the first lamp shows a current of 2.1A (the limit of 5A is selected on the multimeter, look at the lower black scale), the second lamp shows a current of 0.66A. The total is 2.76A, the difference with the charging readings is 0.27A. The voltage dropped to an unacceptable 4.42V.
Well, let's still try to get the most out of this charge - I connect the same 12V H4 lamp as in the first experiment, only using a much shorter USB cable. If you connect it to a running charger, the protection is triggered and the charging is turned off, but if you first connect the load and then apply power to the charger, the lamp lights up:
The charger shows us a current of 3.28A, while the screen flickers noticeably more. The multimeter shows 2.9A current through the lamp. Unfortunately, it was not possible to measure the voltage, since the USB tester was wildly unstable, all the segments on the screen were lit, and the lamp connected through it did not glow. We can conclude that the maximum current that this charger can produce is about 3A, but due to the voltage drop and ripple, no phone will charge.
You can disassemble the charger quite easily by picking up the silver display frame with something sharp. The part that covers the display is held on by latches on the sides. Removing it reveals the inner world of the charger:
The protective film on the screen has not been removed; if you remove it, the numbers on the indicator will be clearer.
If you pull the USB connectors, you can get the charger boards. It consists of two parts connected at right angles - on the larger board there is a pulse voltage stabilizer, on the smaller one there are USB ports, a display and a circuit for measuring and displaying voltage and current.
To summarize, I would like to note that the manufacturer, as always, has specified inflated current specifications; the charger will not be able to produce 4.8A, the maximum you can count on is about 2.4A for both ports. Also, the shape of the charger will not allow it to be used in some cars with a deep cigarette lighter connector. In general, I liked the device; it is convenient that it combines the functions of a charger and a voltmeter; the current measurement function does not seem so useful to me. After the review, I still plan to give the charger to my father, but to do this I will replace the cigarette lighter socket with another, more standard one (since the VAZ 211x has problems with many chargers in the cigarette lighter).
Finally, I want to note that banggood has sales, most recently there was a discount on this charger and it cost $3.69
The product was provided for writing a review by the store. The review was published in accordance with clause 18 of the Site Rules.
I'm planning to buy +10 Add to favorites I liked the review +10 +19I rarely use my car. In essence, it’s not clear why I need it. Well, as a result, the battery always runs out. And every time I have to connect a spare battery, and put the dead one on charge. It is always a painful problem - not to let the battery on your car discharge below normal.
Therefore, I put together this “Car Battery Voltage Indicator” circuit, which I found on the Internet a long time ago and kept with me.
But I changed it a little, and instead of 10 separate LEDs that were in the original circuit, I used a 10-segment LED indicator, because it takes up less space.
Required radio components:
1.tuning resistor 5k – 2 pcs.
2.chip LM3914
3.10 segment LED light bar (I used Kingbight DC-763HWA)
4.resistor R1 4.7k
5. resistor R2 1.2 k
6.For setup you will need a voltmeter and an adjustable power supply from 10 to 15 Volts.
Here is the circuit board of the device.
As you can see in the photo, I cut off one lead from the right tuning resistor.
After installing the parts on the board, the device needs to be configured. Apply a voltage of 10.5 Volts and adjust the right trimmer so that the first bar on the 10-segment indicator lights up.
Apply 15 volts and adjust until the last bar on the 10-segment indicator lights up. And remember, only one strip should always light up. Secure the device in a convenient place.
Now you have a 10-segment indicator showing battery voltage in 0.5 Volt increments.
Not all cars have on-board voltage control installed. Previously, domestic cars had a regular light in the dashboard, which signaled that the battery was charging. This, of course, is not enough information. It would not be amiss to install an additional digital voltmeter or at least an indicator of several multi-colored LEDs showing the main thresholds of permissible voltages. Below are three simple diagrams of LED car voltage indicators.
Voltage indicator on LM393
The operating voltage of the on-board network of a car with a 12-volt battery is considered to range from 11.7V to 14V.
If you go beyond this range, there can be bad consequences, since if the voltage drops below 11.7 V, the battery will suddenly discharge, and if it exceeds 14 V, it will begin to recharge.
To control the car’s on-board network, I propose to assemble a simple indicator consisting of two comparators made on one LM393 chip and three LEDs.
The current voltage is taken from a voltage divider built on resistances R2, R3, R4 and compared with the reference voltage on the zener diode VD1). Normal voltage - green LED lights up, more than 14V - red and yellow LED lights up if the voltage drops below 11.7V
Voltage indicator on K1003PP1
The device allows you to control the voltage of the on-board network in four intervals.
- When the battery voltage is below 11 volts, the red LED-VD1 lights up,
- with a normally charged battery from 11.1 to 13.2 volts, the green LED VD2 lights up,
- in the range from 13.4 to 14.4 volts, the yellow LED lights up - VD3,
- if the overvoltage is more than 14.6 volts, the red LED VD4 will light up.
Adjusting the circuit consists of adjusting a 10K variable resistor to the range of a normally charged battery (12-13.8 V). The phototransistor controls the brightness of the LEDs depending on the level of external light. You can exclude it completely, then the brightness will be maximum.
Multi-level voltage indicator on K1401UD2A
This circuit is also used to monitor the state of the on-board network and allows you to extend the life of the battery, preventing it from being discharged by more than half. This indicator monitors the battery voltage level with very high accuracy and informs the driver about its condition.
The device circuit is made using just one domestic microassembly K1401UD2A and consists of four comparators on operational amplifiers, which, using LEDs HL1...HL4, inform the driver about the current voltage level in one of the intervals. Based on the simultaneous lighting of two indicators at once (or their “blinking”), you can accurately calculate the moment the battery voltage is at the border between the intervals.
If none of the LEDs are lit, then this only means that the battery voltage is below 11.7V. The HL1 glow tells the driver about problems in the operation of the voltage regulator - generator - so when the engine is running, the generator must constantly charge the battery, but the voltage from the stabilizer should not be higher than 14.8 V. If the HL4 LED is on, this indicates that the battery is discharged more than 50% and it needs to be recharged.
The design uses capacitances C1 type K10-17, C2, C3 type K73-9 for 250 V, small-sized tuning resistance R5 type SP3-19a, and the remaining resistances C2-23 (or similar small-sized ones).
The T1 inductor is built on a ring core of standard size K 10 x 6 x 3 from ferrite grade 2000 NM 1. The windings have 30 turns of wire of the PELSHO-0.12 type. When the phases of the windings are switched on correctly, the choke protects the device from ripple and interference in the vehicle’s on-board network when the engine is turned on.
When installing the proposed indicators in a car, you must ensure that its corresponding elements are carefully isolated from the car body. The negative terminal must be isolated from the body, and the positive terminal from the ignition switch. In this case, the voltage indicator will register the battery voltage only while the vehicle is moving.
Always keep your car's on-board voltage under control!
P O P U L A R N O E:
In wired microphones, sooner or later, in places where the microphone or connector is bent, the wire breaks, gets twisted along its entire length and gets in the way. Wheezing, distortion, hum and loss of sound begin. The radio microphone does not have this drawback.
You can buy a radio microphone, but it costs several times more than a regular one.
The simple radio microphone proposed in the article below can be made with your own hands from available elements. You can receive the signal from the microphone using a regular FM receiver.
Point-to-point for beginners. Painting plates.
Spot painting (Point-to-point) is a type of decorative and applied art that has long been known among the Indian and Australian Aboriginal tribes. Today, dot painting is becoming increasingly popular. Using this technique, you can create very beautiful works, even if you don’t have any drawing skills.
The device connects to the vehicle’s on-board network and is designed to quickly determine its status using four LEDs. Which indicate the following voltages:
If two adjacent LEDs blink, then the voltage is at the boundaries of the indicated intervals. Let's take a look at the diagram of the device, which is assembled on just one chip:
Before us are four operational amplifiers D1.1 - D1.4, connected according to the comparator circuit. Each of them, using resistive dividers, is tuned to its own range and controls its own LED. The controlled voltage is supplied to the inverse inputs of the amplifiers, and to the direct inputs - a reference voltage obtained using a simple stabilizer (VD1, R7, C1) and resistive dividers R1 - R6. Thanks to diodes VD2 - VD4, lighting each next LED (from bottom to top) turns off the previous one. Thus, at any given time, only one LED is lit or none is lit (voltage below 11.7 V). Inductor T1 and capacitors C2, C3 form a filter that eliminates impulse noise in the power supply circuits of the device.
The device can use any fixed resistors, which it is advisable to select as accurately as possible. Since there is no 500 Ohm rating in the standard series, resistor R4 is assembled from two 1 kOhm resistors connected in parallel. Trimmer resistor R5 is multi-turn, for example SP3-19a. Capacitors C2, C3 - K73-9 for an operating voltage of 250 V, C1 - type K10-17. In place of VD1, any zener diode of type D818 can work, but the most thermally stable ones are those with the letters E, D and G. Any indicator LEDs with the lowest possible glow current can be used as LEDs (ideally a series of instrumentation devices). Diodes VD2 - VD4 - any pulse.
The choke is made on a K10x6x3 ferrite ring made of 2000NM1 ferrite and contains two windings of 30 turns each, made with PELSHO-0.12 wire. When turning on the choke, it is very important to turn on the windings in concert (the beginning of the windings is indicated by dots), otherwise it will be of no use as a filter. Setting up the device comes down to adjusting resistor R5, which sets the lower indication threshold (below 11.7 V, HL4 has just gone out) and, if necessary, selecting R1 according to the upper threshold (above 14.8 V, HL1 has just lit up). All intermediate ranges will be set automatically. The current consumption of the device should be within 20 - 25 mA.
