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Can I Use a 12V Power Supply to Charge a Car Battery – Charging and Usage

Jan 07, 2023   Pageview:99

Have you ever found yourself in a situation where you need to jump your car, but all you have is a 12V computer cable? It can be pretty frustrating if you don’t know what to do.

A car battery plays the most crucial task of starting the car and running all electrical components. That means your car will only start if the battery is high enough. You may want to replace the battery. But before that, you can try charging the battery.

In this guide, we will be looking at the cable you can use for the task and how to do so. Keep reading:

Can a Computer Power Supply Charge a Car Battery?

There is a lot of review from various experts concerning this topic. Some agree that supplying enough charge to a car battery with a 12V cable is easy, while others feel that it might not work efficiently.

So, what is the correct answer? We carried out a small experiment to determine the effectiveness of such cables, and the results were quite positive.

You can use a 12V power supply to charge our car battery. However, the battery will not charge fully because you need a higher power supply.

Also, the charging process will be very slow. It requires patience to wait until you have enough charge in your battery.

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Charge for 18 hours can then check the voltage. If it has attained 11.5 volts or more, it’s ready to start the car. You can turn on the engine and then continue charging for about 30 minutes.

Factors to Consider

As stated above, you can charge your car battery with a laptop cable. However, it’s not ideal and, therefore, not recommended. In most cases, this will only work in theory, which is why many people don’t even bother to try.

Here are factors to consider before you use the cable.

Battery Nominal Voltage

The least voltage required for a car battery to work is 12V. That means it requires a little higher voltage to charge it. If you have a lead acid battery, you will need 13.8 to 14.4v to charge it. This will not come from the computer cable.

The computer cable is not designed for such a heavy load.

A laptop cable is intended for use only with a laptop. Note that partially discharged 12V batter carries a voltage higher than this. Connecting a computer cable may reverse the process - discharging instead of charging. The power supply will detect too much power in the output and try reducing it.

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You may need a circuit to limit the current.

You can easily damage the battery or power supply using the wrong cable. This will depend on the type and size of your battery. It’s therefore recommended that you measure the current and use some regulator.

Most computer power cables only work with some minimum load.

There is a good reason why you should only power on a computer with a load. The cable may be damaged and extend to the battery.

Should you use the laptop cable?

As you can see charging a car battery with a laptop power supply is possible. But it’s not ideal. The cable is filtered to deliver a smooth DC output. A lead acid battery is charged better using a power that is not filtered.

The 12V DC cable may not supply enough amps to initiate the charging process if the battery is completely drained. This could cause the fuss to blow. The cable will burn if it’s not surge-protected.

If you don’t have any other option, there are ways of including current limiting resistors to the system and then removing them one by one as the battery charges. But the process is too complex and probably not worth the trouble.

Bottom line: buy a new charger for your car battery. It does not cost much. It will also save you from buying another battery since using the wrong cable can damage it.

Can I Charge a 19V Laptop with a 12V Charger?

No. You should never charge a 12V AGM battery directly using a 19V laptop power supply. You damage the battery and are forced to buy another one.

Here is what you need to know:

You need a battery charger: For a laptop; the power is not in the charge but a fixed voltage SMPS power supply for power. The charger is inside the machine and is only activated by the cable.

A fully charged AGM lead acid battery starts with a voltage of 13.8 to 14.5V. That means the cable will not work properly.

A parallel arrangement will not change the nominal voltage. It only increases the current capacity and hence is not able to charge.

You can try a series arrangement, but that will require up to 27.6V to get fully charged. A power supply cable will not perform such a heavy task.

What should you do then? Invest in a high-quality charger. Or, if you have the time, build a charger that allows you to use the 19V power supply.

To build the charger, you will need a terminal voltage control, a current control, and a float, trickle or charge control switch. It might be much easier and more convenient just to buy a charger instead.

The bottom line is you cannot use the cable. The voltage level is not the only factor that determines the charging of a car battery. There are other factors, like the charging circuit, current control, and temperature, which affect the whole process. You will end up damaging the battery.

Can I Jump on a Car with a 12V Power Supply?

No. The cable will not work. You need a power supply that provides more than 12V to jump the car battery.

A fully charged car battery reads 13.5V more. A 12V power supply can put something small, maybe just enough to start the car. But this will take too long.

Jumpstarting a dead battery is something else. It requires high voltage passing through the cable into the dead battery. It can be too much for the cable.

Invest in a jump starter instead, and you will never have to worry about some of these issues. There are affordable chargers that will do the job effortlessly.

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