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» »12V auto charger
This is a very simple set-top box for your existing charger. Which will control the charge voltage of the battery and when it reaches the set level - disconnect it from the charger, thereby preventing overcharging of the battery.
This device has absolutely no scarce parts. The whole circuit is built on just one transistor. It has LED indicators that indicate the status: is charging or the battery is charged.

Who needs this device?


Such a device is sure to be useful to motorists. Those who have a non-automatic charger. This device will make of your ordinary charger - a fully automatic charger. You no longer have to constantly monitor the charging of your battery. All you need to do is put the battery in charge, and it will turn off automatically only after it is fully charged.
12v auto charger

Auto Charger Scheme


12v auto charger

Here is the circuit of the automaton itself. In fact, this is a threshold relay that trips when a certain voltage is exceeded. The threshold is set by a variable resistor R2. For a fully charged car battery, it is usually equal to 14.4 V.
You can download the scheme here -

Printed circuit board


12v auto charger

How to make a circuit board, you decide. It is not complicated and therefore you can easily throw it on a breadboard. Well, or you can get confused and do it on textolite with etching.

Customization


If all the details are serviceable, the configuration of the machine can be reduced only to setting the threshold voltage with resistor R2. To do this, we connect the circuit to the charger, but we do not connect the battery yet. We translate the resistor R2 to its lowest position according to the scheme. We set the output voltage on the charger to 14.4 V. Then we slowly rotate the variable resistor until the relay trips. Everything is configured.
Let's play with the voltage to make sure that the console works reliably at 14.4 V. After that, your automatic charger is ready to work.

Watch the video of the charger



In this video you can see in detail the process of the entire assembly, adjustment and testing in operation.
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Comments (9)
  1. Alexander
    #1 Alexander Guests February 6, 2018 00:52
    11
    If you expand the LEDs, they will even light up!
  2. Dmitry
    #2 Dmitry Guests February 6, 2018 18:11
    8
    14.4 volts is about 80% of the charge, approximately. It is necessary, at least, 15.3 volts, with respect to most batteries.
  3. Marat
    #3 Marat Guests February 11, 2018 09:22
    4
    I understand the article has been rewritten, but I want to know if the circuit saves from the polarity reversal?
  4. Hawkar fariq
    #4 Hawkar fariq Guests February 13, 2018 11:03 p.m.
    2
    Thanks for sharing my video.
    You can download the circuit here.

    http://www.mediafire.com/file/0ldtxs4ma6mt2q2/12V-Auto-Cut-Off-Charger_circuit_By_hawkar_Fariq.pdf
    1. feelloff
      #5 feelloff Guests February 14, 2018 07:24
      0
      Thanks you! Link to article text added.
  5. Guest Igor
    #6 Guest Igor Guests February 26, 2018 9:05 p.m.
    0
    At the output, for some reason, the voltage is 6 with a penny volts, at the input 14.6. The relay rattles at the moment of switching, there are no clear counts. LEDs installed correctly. Who is aware of this problem?
    1. Guest Vlad
      #7 Guest Vlad Guests October 16, 2018 8:33 p.m.
      0
      And it will rattle due to the lack of a voltage regulator.
  6. rybakov.anatoliy
    #8 rybakov.anatoliy Guests December 13, 2018 19:09
    3
    The circuit must be connected to the battery (i.e. after the contacts). Then the relay will not rattle, and the charger will not only turn off, but also connect when the voltage drops on the battery. Between "plus" and "minus" (after the rectifier) ​​you need to connect an electrolytic capacitor with a capacity of at least 100 microfarads. At the same time, my voltage increased to 18 V.
  7. 13007
    #9 13007 Guests May 21, 2019 21:53
    0
    But will it not be more reliable to implement the circuit not on a relay, but on a thyristor?

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