Thursday, November 15, 2007

Automatic 12V Lead Acid Battery Charger

Charger Aki 12 V Otomatis

This charger will charge any 12V lead acid battery including flooded, gel and AGM. It is fully automatic and will charge at a rate up to about 4A until the battery voltage reaches a preset point at which it will switch to a very low current float charge.

If the battery voltage drops again the charger will begin charging until the voltage once again reaches the cut off point. In this way it can be left connected to a battery indefinitely to maintain full charge without causing damage. An LED indicates when the battery is fully charged.

R2 will have to be adjusted to set the proper finish charge voltage. Flooded and gel batteries are generally charged to 13.8V. If you are cycling the battery (AGM or gel) then 14.5V to 14.9V is generally recommended by battery manufacturers.

To set up the charger, set the pot to midway, turn on the charger and then connect a battery to it's output. Monitor the charge with a voltmeter until the battery reaches the proper end voltage and then adjust the pot until the LED glows steadily. The charger has now been set. To charge multiple battery types you can mount the pot on the front of the case and have each position marked for the appropriate voltage.

Q1 will need a heatsink. If the circuit is mounted in a case then a small fan might be necessary and can generally be powered right off the output of D1.

T1 is a transformer with a primary voltage appropriate to your location (120V, 220V, etc.) and a secondary around 12V. Using a higher voltage secondary (16V-18V) will allow you to charge 16V batteries sometimes used in racing applications.

If the circuit is powered off, the battery should be disconnected from it's output otherwise the circuit will drain the battery slowly.

Charger aki ini bisa digunakan untuk aki jenis apa saja. Rangkaian ini otomatis, mampu mengisi aki dengan arus 4 A hingga voltase aki mencapai titik tertentu. Pada titik ini arus pengisian menjadi sangat kecil.

Jika voltase aki berkurang lagi, rangkaian akan kembali mengisi aki hingga mencapai titik voltase tadi. Jadi, rangkaian bisa tetap disambungkan ke aki agar aki selalu dalam kondisi penuh tanpa harus takut merusak aki. Sebuah LED akan menyala untuk menandakan bahwa aki sudah penuh.


R1, R32330 Ohm 1/4W Resistor
R21100 Ohm 1/4W Pot
R4, R5, R7, R8482 Ohm 2W Resistor
R61100 Ohm 1/4W Resistor
R911K 1/4W Resistor
C11220uF 25V Electrolytic Capacitor
D11P600 DiodeDiode penyearah 50 V 5 A atau yang lebih besar lagi
D211N4004 Diode1N4002, 1N4007
D315.6V Zener Diode
D41LED (Merah, Hijau, atau Kuning)

T1112V 4A TransformerLihat Catatan
F113A Sekering
S11SPST Switch, 120VAC 5A
Lain-lain1Kabel, PCB, Heatsink untuk U1, Casing, Jepit buaya untuk aki mobil, sekering dan rumah sekering


  1. R2 harus diatur untuk menentukan batas voltase yang diinginkan. Aki basah biasanya di-charge dengan voltase 13,8 V, sedangkan aki kering dan semi kering 14,5 - 14,9 V. Cara mengesetnya, putar potensio R2 hingga berada di posisi tengah, hidupkan charger, pasang aki yang akan di-charge. Amati proses pengisian dengan voltmeter hingga voltase aki mencapai voltase yang diinginkan. Kemudian putar potensio R2 hingga LED menyala. Charger sudah siap digunakan sekarang. Untuk men-charge berbagai macam tipe aki, lakukan hal yang sama untuk tiap aki dan tandai posisi potensiometer R2 untuk tiap tipe aki.
  2. Q1 harus diberi heatsink. Jika rangkaian dikemas dalam casing, maka diperlukan fan kecil yang bisa dicatu dari keluaran D1.
  3. T1 adalah transformator dengan voltase primer sesuai dengan voltase lingkungan kerja Anda, dan sekundernya sekitar 12V. Dengan voltase yang lebih tinggi (16 - 18V), Anda bisa men-charge aki dengan voltase 16V.
  4. Jika rangkaian dimatikan, aki harus dilepas dari rangkaian, jika tidak maka rangkaian akan menguras aki pelan-pelan.

Saturday, November 10, 2007

12 V Car Battery Charger

Charger Aki Mobil 12 V

Most car battery chargers are simple devices that continuously charge the battery with a few amperes for the duration it is ON. If the charger is not switched OFF in time, the battery will overcharge, its electrolyte lost due to evaporation, and its plate-element will likely be destroyed.

The circuit above will eliminate these problems by monitoring the battery's condition of charge through its retroactive control circuit by applying a high charge current until the battery is completely charged. When charging is complete, it turns on the red LED (LD2) and deactivates the charging circuit.

This circuit is drawn to charge 12V batteries ONLY. Certain emphasis should be taken when wiring up this circuit. They are the connections of the transformer to the circuit board, and those supplying current to the battery being charged. These connections should be made with cables having a large cross-sectional area to prevent voltage-drop and heat build-up when current flows through them.


After assembling of the circuit, adjust TR1 to null value, power-up and make the following adjustments :

  1. Without connecting the battery check that the 2 LEDs are turned on.
  2. Connect a car battery to the circuit and check that LD2 is OFF and a current (normally 2A to 4A) is flowing to the battery.
  3. Adjust TR1 until LD2 turns ON and the charge current is cut.
  4. Adjust TR1 to null value and charge the battery using the hydrometer technique (if you do not have or do not know how to use a hydrometer, then use a good condition battery and charge).

Carefully adjust TR1 so that LD2 begins to turn ON and the charge current falls to a few hundred milliamps (mA). If TR1 is set correctly then in the next round of charging you will noticed LD2 begin to flicker as the battery is being charged.

When battery is completely charged, LD2 turns ON completely.TR1 does not need further adjustment anymore. Q1 is connected in line with the battery and is fired by R3, R4 and LD2. The R2, C1, TR1 and D2 sense the voltage of the battery terminal and activate Q2 when the voltage of the battery terminal exceeds the value predetermined by TR1.

When an uncharged battery is connected, the terminal voltage is low. Under this circumstance, Q2 is turned OFF and Q1 is fired in each half cycle by R3, R4 and LD2.

The Q1 functions as a simple rectifier and charges the battery. If the battery terminal voltage is increased above the level that had been fixed by TR1, then Q2 shifts the control of Q1 gate. This deactivates Q1 and cuts off the current supply to the battery and turns LD2 ON indicating that the charge has been completed.

Q1 and bridge rectifier GR1 should be mounted on heatsinks to prevent overheating. M1 is a 5A DC ammeter to measure the charge current. Optionally a voltmeter can be connected in parallel with the battery, however it must have a high input resistance so as not to influence the measurement.

R1= 1KohmsD1= 1N4001T1= 220V/17V 4A Transformer
R2= 1.2Kohms              D2= 6.8V 0.5W zenerLD1= Green LED
R3= 470 ohmsTR1= 4.7Kohms trimmerLD2= Red LED
R4= 470 ohmsQ1= BTY79 or similar 6A SCR  M1= 0-5A DC Ampere meter
R5= 10KohmsQ2= C106D SCRS1= 10A D/P On-Off Switch
C1= 10uF 25VGR1= 50V 6A Bridge RectifierF= 5A Fuse

Kebanyakan alat pencharge aki merupakan rangkaian sederhana yang terus menerus mengisi aki selama rangkaian dihidupkan (ON). Jika aki sudah penuh dan rangkaian tidak dimatikan (OFF) maka akan terjadi overcharge, yang bisa menyebabkan penguapan cairan elektrolit dan merusak elemen-elemennya.

Rangkaian di atas dapat mengatasi hal seperti itu dengan memonitor kondisi pengisian aki melalui rangkaian kontrol retroaktif yang mengalirkan arus besar ke aki hingga aki terisi penuh. Ketika aki sudah terisi penuh, LED LD2 akan menyala dan mematikan rangkaian pengisi.

Hal-hal yang perlu diperhatikan:

  • Rangkaian ini hanya untuk mencharge aki 12 V
  • Semua kabel yang digunakan untuk menyambung komponen termasuk ke aki harus menggunakan kabel dengan kapasitas arus besar agar tidak ada tegangan jatuh atau rugi-rugi panas yang terjadi


Setelah rangkaian siap, trimpot TR1 dibuat nol kemudian rangkaian disetel:
  • Sebelum menyambung ke aki, pastikan kedua LED menyala dengan baik.
  • Pasang aki, pastikan LED LD2 mati dan arus yang mengalir sebesar 2-4 A.
  • Atur trimpot TR1 hingga LED LD2 hidup dan arus berhenti mengalir.

Friday, November 9, 2007

Simple Car Battery Charger

Charger Aki Mobil Sederhana

by: Naveen P N

This very simple circuit uses a transformer ,two diodes , a capacitor and an ammeter.
To charge a battery just connect the + and - terminals of the circuit to the corresponding terminals of the battery.
When the battery is not charged, the ammeter reading shows 1-3 amps.
When the battery is fully charged the ammeter reads Zero or nearly zero, after which the battery should be removed from the
The circuit is a full wave rectifier using 2 diodes for rectification. The capacitor is used for smoothing.
I think the circuit works fine without the capacitor since the battery itself acts a BIG capacitor. But when you are using the
circuit to supply 12V (as a battery eliminator) the capacitor needs to be present.
Care should be taken NOT to reverse the + and - terminals while connecting it to the battery.

Charger/carjer/cas aki mobil sederhana ini hanya menggunakan sebuah transformator, kapasitor, ammeter, dua dioda.

Untuk mencharge aki cukup sambungkan terminal (+) dan (-) rangkaian ke terminal yang sesuai pada aki. Ketika aki belum penuh, pembacaan pada ammeter menunjukkan angka 1-3 A. Jika aki sudah penuh pembacaan ammeter mendekati angka 0 (nol). Pada saat ini, aki harus dicabut dari rangkaian.

Rangkaian yang digunakan ini adalah penyearah gelombang penuh dengan 2 dioda. Kapasitor yang digunakan hanya untuk menghaluskan keluaran, tapi rangkaian tetap akan berfungsi baik tanpa kapasitor karena aki itu sendiri merupakan kapasitor besar. Namun, bila rangkaian hendak digunakan sebagai power supply 12 V, kapasitor sebaiknya digunakan.

Hati-hati jangan sampai terbalik memasang terminal (+) dan (-) rangkaian ke aki.