Learning, Battery,

Do Car Batteries Come Charged? (Types & Tips)

If you’re concerned about whether a new car battery comes charged, perhaps because you don’t have a charger, rest assured…

New battery suppliers normally sell charged batteries. A sticker might state the date it was last charged. The charge, usually at least 80-90%, should be sufficient to start the car. It will have also been charged at the factory during testing and to extend its lifespan. Still, it’s advisable to trickle charge it after buying it if it won’t be used immediately, as lead-acid batteries naturally self-discharge at around 4-6% monthly.

Only a used or reconditioned battery might not come charged. But, as long as it has enough charge to start the car, you can recharge it fully by simply driving.

I explain why new car batteries come charged, how to check whether you need to buy a new one, and what to do when buying and installing it below.

Why Do Car Batteries Come Charged?

New car batteries normally come charged when you buy them, but let’s consider why or why pre-charging them is necessary.

Factory Charging

Car batteries are charged at the factory for two reasons.

One reason is to test them to ensure they can hold a charge, a quality control measure. A series of tests check for the following:

  • Each battery’s SOH and SOC (state of health and charge)
  • The battery’s service life
  • The battery’s current state

These tests involve measuring:

  • The battery’s charge capacity in mAh (milliampere-hours)
  • The voltage across its terminals
  • Its safe depth of discharge (DoD) as a charge percentage

Retailer Charging

The retailer might also charge the battery, especially if it’s over a few months old.

This is necessary to maintain its charge because if it’s not recharged, it will self-discharge naturally, even while unconnected, at about 4-6% per month.


Are You Buying a Used Battery?

If you’re buying a used car battery, the situation differs from buying a new one.

Whereas a new battery will most likely come charged, a used one might or might not. It is entirely at the seller’s discretion to charge it or not. But would you buy a battery without checking it?

Unless you’re getting the used battery for free, I suggest you check it properly before buying it. Have it charged or charge it yourself and then check whether it can hold that charge well. See the section below on checking a battery’s voltage.

Don’t buy the battery if it cannot hold a charge, if it’s damaged in any way, or if it’s too old (over 4 years).

If it’s a reconditioned battery, it will probably come charged but don’t expect it to last long. It might give you a few months or up to a year if you’re lucky.


Charging the Car Battery

Although the car battery will likely be fully or almost fully charged when buying it, you should still check the voltage, and you might need to recharge it.

Manufacturer’s Advice

Follow the manufacturer’s advice when installing a new battery.

They might issue instructions to charge the battery for hours or overnight before installing it in the car. The advice differs between brands and models but also depends on the battery’s charge. Only charge it if necessary, and avoid overcharging it.

How New is the Battery?

You should try to buy a new car battery that is no more than 3 months old.

If you manage to do that, it should have enough charge to install and use immediately. Any shortage of charge will be replenished simply by driving by the car’s alternator, which will generate electricity to store.

Trickle Charging

a black & decker smart battery charger
Black and Decker Battery Charger attached with battery to charge it

If you’re unsure how much charge the new battery has, use a voltmeter to check the voltage across its terminals before installing it.

It should be within the range of 12.3-12.8 volts if fully or almost fully charged. If it has enough charge to start the car (~12.4 volts), I suggest you install it and drive it to let its alternator charge it fully.

If it doesn’t have sufficient charge, connect it to a smart float or trickle charger to ensure it is fully charged before using it. It will supply a gentle charge to compensate for the shortfall and replenish the discharge once fully charged to keep it at full-charge capacity without overcharging it.

You don’t have to use a smart charger before installing or removing a battery from the car. You can install or keep the battery in the car but disconnect the cables. Then, connect the charger’s cable and the charger itself to an AC power outlet.

It’s a good idea to trickle-charge the battery anyway, every few months or when leaving the car unused for a long period.

charging the battery while installed in the car


When Do You Need to Buy a New Battery?

If you’re deciding whether to buy a new battery because the existing one is weak, yes, a new one will come charged but consider the following:

Battery’s Lifespan and Condition

If the battery is over 2.5-3 years old, it’s probably nearing the end of its lifespan. A typical lead-acid battery will last around 3-4 years, or up to 5 only if well-maintained.

Also, inspect the battery for cracking, swelling, or deformation signs. The battery could be leaking or about to and needs to be replaced. Don’t use a damaged battery, as it can be very dangerous.

The Battery’s Terminals and Cables

Check the battery’s terminals for corrosion, which might prevent it from charging properly.

You might not need to change the battery unless it’s old or damaged. Detach the cables momentarily and clean the terminals.

Also, inspect the cables to ensure they are not broken or frayed. If they are, you might only need to change the cables.

Check the Battery’s Voltage

load test on battery
Video | Justin Miller

Check the battery’s voltage to see if the battery is holding enough charge and conduct a load test.

You will need a voltmeter or multimeter calibrated to 20 DC volts. Attach the positive (red) probe to the battery’s positive (+) terminal and the black one to its negative (-) terminal.

Without the car turning on, the voltage should be no less than 12.2 volts and 12.8 volts. It’s undercharged if it’s less or overcharged if it’s more. You can reduce the excess charge by turning on the headlights for a while, but if it’s undercharged, you must charge it; otherwise, the car might not start.

If the battery weakens quickly after recharging and driving, either the battery is weak or the alternator is faulty.

If the load test (while some accessories are on) shows high consumption, check that accessory instead.


Advice When Buying a Car Battery

Don’t worry about the charge if you need a new battery. It will likely come charged but ask the seller if you’re unsure.

Here is some more advice when buying a new battery:

  • Buy your car battery from a reputable battery supplier
  • Ensure the battery is sealed and not tampered with.
  • Trickle or float charge the battery when not used for a long time.
  • Avoid buying a battery that is more than 3 months old.



References

Black and Decker Battery Charger. https://www.amazon.com/BLACK-DECKER-BC15BD-Battery-Alternator/dp/B00KNMKRU8/

Charging the battery. https://www.publicdomainpictures.net/en/view-image.php?image=338842&picture=car-battery-on-charge

Video References

Century Batteries

Justin Miller

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About Alex Robertson

AvatarCertifications: B.M.E.
Education: University Of Denver - Mechanical Engineering
Lives In: Denver Colorado

Hi, I’m Alex! I’m a co-founder, content strategist, and writer and a close friend of our co-owner, Sam Orlovsky. I received my Bachelor of Mechanical Engineering (B.M.E.) degree from Denver, where we studied together. My passion for technical and creative writing has led me to help Sam with this project.

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