How Many Amps does A Car Battery Need to Start [Ultimate Guide]

The car battery always needs to be in the best condition for you to start the car and run any electronic accessories attached to it.

You have probably come across terms such as volts and amps. These are simply the unit of measure that we will look at to help answer the question in the topic.

Volts and Amps

Amp or ampere is a unit of measure for current that the battery can deliver. On the other hand, voltage is simply the measure of the electric potential across the two terminals of the battery.

If you have not done electronics in your life, this might seem like a hard concept to grasp, but it is not. We can use another analogy below for you to see it.

Consider water flowing through the pipe. The water in this case is electricity. So, the speed at which water flows is current and we measure it as amperes or amps.

Now, the pump pushing this water to go through the pipe is the battery thus the pressure generated can be equated to voltage or volts.

See, that wasn’t so hard.

Here is a video explaining the battery capacity for more details

How amps are measured and recorded in a battery?

Now onto our question of how many amps are in a car battery. It is vital to know that there are several ways of measuring the current in a battery which we discuss below.

1. Amp Hours (Ah)

Amp-hours or Ah means the highest amount of current that can be drawn from the battery continuously for one hour before it no longer has power or goes flat.

An example is when a car battery has a rating of 50 amp-hours. This means it can the battery can provide a maximum of 50 amperes of current continuously for one hour before it is flat.

Expect to find car batteries with an amp-hour rating from 50 to 500 amp hours depending on size and application.

2. Cranking Amps (CA)

This is another important term you may see as a label on your battery. Well, cranking amps or CA means the amount of current you can draw from the battery for a period of 30 seconds while operating at a temperature of 32 degrees F.

However, you may notice cold-cranking amps being used more often.

3. Cold Cranking Amps (CCA)

The CCA rating of a battery shows you how much current you can draw from the battery for 30 seconds while at a temperature of 0 degrees F.

This is an important factor as sometimes you have to start the car in extremely cold conditions. So, you have to know that the battery can deliver enough current necessary for starting the car.

The amount of CCA needed to start the car depends on the model. Most cars right now need around 300 amps to start. Expect to find batteries with a CCA rating of 400 amps or more.

SUVs and trucks would require more current because of their bigger engines. So, they might have batteries with 800 CCAs.

Large vehicles can use batteries with 1,500 CCAs, which is quite a large amount of power needed to start the engine.

Charging the Car Battery

To understand how charging works, we first need to consider the capacity of the battery first.

Car batteries are mostly rated with a capacity of 48 amp-hours. Such means that a 12-volt system that can deliver 1 amp of current will charge the battery for 48 hours. You can also consider it another with 2 amps capacity that can charge for 24 hours.

With the capacity in mind, the basic charger for a car battery delivers 2 amps and thus can charge the 48 amp hour battery in a period of 24 hours.

In case the battery is partially charged, then the time will depend mostly on the battery condition and the level remaining to be charged.

Here is a video detailing more on how to recharge a car battery

How about using a charger with higher amps?

That is something some people might consider since they want to charge their car batteries faster.

Yes, it is possible to charge the car battery with a charger capacity of 10 amps. As you can see, you will be able to shorten the charge time, but at what expense?

Fast charging might not always be recommended as sometimes it may cause damage to the plates of the battery. So, stick to the recommended charger by the battery manufacturer.

FAQs

How many amps are needed to start an engine?

It depends on the engine size. For small cars, 300 amps should be enough to start the car’s engine. Expect the larger engines to use more power.

How long does a battery take to be fully charged while driving?

The alternator can have the battery charged in about 30 minutes. In most cases, the battery would not be flat, so it takes lesser time.

Will the CCA of the battery change with time?

Yes. A new battery will have a higher CCA. However, heat, vibration, and normal wear and tear can mean that your battery experiences loss in total capacity including CCA too.

How many amps does a car alternator put out?

The alternators vary a lot based on size. Most cars would have alternators with a rating of 65 to 100 amps. This is the best rating for running various accessories such as the fuel pump, headlights, stereo, and others.