How to charge a car battery with a laptop power supply

How to charge a car battery with a laptop power supply

If you need to charge a car battery, but the charger is not at hand, then a laptop power supply can easily replace it. Typically, such units produce 18-19 Volts with a maximum load of 3-4 Amperes. This will be enough for us to “refresh” or fully charge the battery.

Will need


  • Alligator clips (You can do without them by making loops from wire).
  • 55 W halogen lamp (If you don’t have one, you can take two 21 W lamps and connect them in parallel).
  • Wires with a cross-section of at least 1.5 sq. mm.
  • Multimeter.
  • Laptop power supply.

We charge the battery with a laptop unit


The battery is standard 12V, 60 A/h. We measure the initial voltage on the battery.
How to charge a car battery with a laptop power supply

About 8 Volts, which means a deep, even complete discharge. To facilitate the release of gas, unscrew all filler plugs.
We take a halogen lamp and screw the wires to its contacts.
How to charge a car battery with a laptop power supply

We find the plus and minus in the contacts of the block from the laptop. We connect the source to the battery, and turn on a halogen incandescent lamp in the gap. It will play the role of a quenching resistor.
How to charge a car battery with a laptop power supply

We connect the block to the network. We check the charging process with a multimeter.
How to charge a car battery with a laptop power supply

Charging is proceeding correctly, the battery has begun to gain charge.
We translate multimeter into the current measurement and connect it to the open circuit.
How to charge a car battery with a laptop power supply

The charging current was more than 2 amperes. Which, in turn, is not enough for the capacity of such a battery, so you will have to increase the charging time.
After a day, the current decreased. We check the density of the charged battery using a hydrometer.
How to charge a car battery with a laptop power supply

The electrolyte density is completely normal. The battery is fully charged, as indicated by a voltage of 14.4 Volts. Disconnect the homemade charger. Screw in the plugs of the filler neck compartments.

Conclusion


The battery was fully charged after one day. The power supply from a laptop can be used not only as a temporary charger, but also as a permanent one.
So taking your laptop with you on trips is a great idea.

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