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How to Use a Car Battery Charger

Just as any other part of your car’s system, your car battery can also get overworked. So, if you wake up to a flat battery, don’t fret as you can always recharge it. But first, what exactly causes a flat battery? Continuous starting and stopping and frequent short trips are the main culprits.

However, note, your battery is more likely to be drained in winter as it works twice as hard to keep the headlights, wiper and heater on most of the time. With that said, here’s how to safely use a car battery charger as well as all you need to know about car batteries and chargers.

How Much Charge Does a Car Battery Hold?

Mechanic charging car battery

If properly charged and in tip-top shape, an average car battery will usually have a capacity of 48-amp hours. This is enough to power your car for a long time. So, how does it manage to maintain this charge without you having to recharge it always? Well, note, a car battery is charged either using the alternator or a charger that we’ll talk about later in this article.

An alternator recharges it every time your car engine is running. This means even if it’s low, it’s automatically replenished whenever your car is running. However, the alternator doesn’t charge the battery alone. It also powers headlights, your heater, air conditioning, and other accessories that you turn on while in the car.

This and the frequent start and stops, especially in traffic or at a stoplight tends to create a significant load that your alternator is sometimes unable to handle, causing a drain on the car’s battery. This is why you may get home well, pack your car just fine and wake up to a flat battery. When this happens, you can always jump start it. But what if it dies again before you reach your destination? In that light, the best option is to recharge your car using a car charger.

How Long Does It Take to Recharge a Car Battery Using a Charger?

Jumper cables charging battery on a car

There is no definite answer for this as it all comes down to the type of charger in use. Here are some of the most common chargers you will find today.

1. A 40 Amp Car Battery Charger

A 40-amp car charger is incredibly fast and using this to recharge your car means you can always start it within a few minutes even if your battery was almost dead. A 40amp charger is a great accessory to own, especially if you travel a lot as they get you up and running quickly. However, their fast-charging capabilities are also their weakness.

Why? There’s a high probability you may end up overcharging and damaging your car battery especially if the 40amp charger you’re using doesn’t feature automatic shut-off. So, if you’re using this one, you need to be there the whole time. A 10 amp charger is also relatively quick and will often complete charging your car battery in about 4 hours.

2. A 4 Amp and 2 Amp Charger

These are basic car chargers and will often take long to recharge your car batteries. They are ideal if you’re not in a hurry or if you’re recharging a car you rarely use. Given that an average car battery has 48 amps, a 4-amp charger will often take 12 hours while a 2 amp one will have you waiting for the next 24 hours. Low amperage chargers like these can recharge your car but are ideal if you’re trying to recharge a smaller battery, for instance, a motorbike’s.

How to Recharge Your Car Battery Using a Charger

Man charging car battery

Now that you know how long it takes, make sure you have a charger compatible with your car’s model and then follow the steps below.

1. Disconnect the Battery Terminals

Disconnect the battery terminals before you connect the charger. This is especially essential if you have an alternator (which you most likely do) as failure to do so could impose permanent damage on it. The positive terminal as always is marked with a + while the negative one has a -. In some cases, a car’s terminals are usually covered by plastic caps. So if you can’t see the mentioned signs, remove the plastic covers first.

2. Connect the Charger to the Battery

The next step is to connect the charger to the battery. But before you do, check to ensure it’s still unplugged or the power switch is off. This is essential as connecting a charger while it’s connected to the source of power means it has current flowing through it and could pose a danger to you.

Once you’ve confirmed the mentioned, you can now connect your charger to the battery. Connect the red charger cable to the positive+ and the black cable to the negative- terminal. Keep the charger as far away from the battery as you can and then connect the charger to the source of power and turn on the power switch.

3. Choose Between Trickle and Fast Charging

If your car’s charger has these options, choose between trickle and fast charging. If you are in no hurry, trickle charging is the way to go as it gives the best results. But if you need to be up and running in a few, fast charging will also work.

4. Turn on the Automatic Shut Off Feature

Again, if your charger has the automatic shut off feature, it’s always advisable you use this option, so you don’t have to keep on monitoring the charging process. If not, then you will have to do it manually.

5. Disconnecting

Once your battery is full, then disconnect the cables. Start with the negative (black cable) and then the positive (red cable). Once this is done, you are now good to start your car and drive into the sunset!

What to Do If It Dies Again

Once you fully charge your car’s battery, a flat battery should be the least of your worries in the near future. But if it weakens or dies a few hours or days after you recharge it, then it probably has a problem. Consider stopping by your auto-mechanic’s store to have it checked out, or buy a new one.

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