# What amperage is a car battery?

Last Update: April 20, 2022

This is a question our experts keep getting from time to time. Now, we have got the complete detailed explanation and answer for everyone, who is interested!

**Asked by: Raleigh Hansen**

Score: 4.6/5 (28 votes)

An average car battery has a capacity of around **48 amp hours** which means that, fully charged, it delivers 1 amp for 48 hours, 2 amps for 24 hours, 8 amps for 6 hours and so on.

## How many amps does a 12 volt car battery have?

Car batteries will typically have a capacity of **48 amp hours**. What this means is a fully-charged 12-volt car battery rated at 48 amp hours can deliver 1 amp for 48 hours or 2 amps for 24 hours.

## How do I know what AMP my car battery is?

Volts are a measure of voltage, while amps are a measure of current. You can find the amps from the voltage if you know the battery's resistance, using the formula known as Ohm's Law: Current equals voltage divided by resistance, or **I=V/R**. The ohm rating of your battery should be listed on the label.

## Should I charge my car battery at 2 amps or 10 amps?

It is **best to slow charge the battery**. Slow charging rates vary depending on the battery's type and capacity. However, when charging an automotive battery, 10 amps or less is considered a slow charge, while 20 amps or above is generally considered a fast charge.

## What is the current of a car battery?

Car batteries provide **12.6V DC** (direct current) through six cells, producing 2.1V each. Anything under the 75% charge rate, or about 12.45V, generally indicates the battery is undercharged and will need recharging.

## Amp Hours??? Battery Capacity Explained

**28 related questions found**

### What should a 12 volt battery read when fully charged?

A fully charged battery will typically display a voltmeter reading of about **12.6 to 12.8 volts**. If your voltmeter is showing a voltage anywhere between 12.4 and 12.8, that means your battery is in good shape. Any voltage above 12.9 volts is a good indicator that your battery has excessive voltage.

### How many volts does a car battery need to start?

The normal voltage needed to start the car begins from **12.6 volts**. At the time of exploitation, this parameter is between 13.7 to 14.7 volts.

### Should I charge my car battery at 2 amps or 6 amps?

Consequently, when trying to charge a larger battery at that rate, it will take a very long time and the battery may discharge at a greater rate than the 2-amp charge can provide. It is better to charge a **deep cycle battery** at a higher charge rate like 6-amps, 10-amps or higher.

### Is it OK to leave a car battery charger on overnight?

Even though there is no risk of overcharging with the use of a high quality charger, **the battery should not remain connected to the charger for more than 24 hours**. A full charge is usually achieved by charging overnight. ... Even after a deep discharge, some chargers enable at least partial reconditioning of the battery.

### Can you overcharge a car battery at 2 amps?

A: If you leave the charger connected continuously, even at a mere 2 amps, **the battery eventually will die**. Overcharging a battery causes excessive gassing — the electrolyte gets hot and both hydrogen and oxygen gas are generated. ... On sealed batteries, the buildup of gases could cause the battery to burst.

### How long does it take to charge a car battery at 2 amps?

How Long To Charge A Car Battery At 2 Amps? It will take a lot of time to charge a car battery using a 2amp charger. The average time to charge a 48amp battery fully, using such a charger is **24 hours**.

### How many amps is a car alternator?

Alternator ratings range from about **60 or 70 amps up to 150 amps or more** on many late-model vehicles. Some high-output alternators can generate upward of 200 amps. The amp rating of the alternator is matched to the vehicle's electrical system.

### How do you calculate the current of a battery?

To get Wh, **multiply the Ah by the nominal voltage**. For example, lets say we have a 3V nominal battery with 1Amp-hour capacity, therefore it has 3 Wh of capacity. 1 Ah means that in theory we can draw 1 Amp of current for one hour, or 0.1A for 10 hours, or 0.01A (also known as 10 mA) for 100 hours.

### How many volts is 50 amps?

A 50 amp plug has four prongs – two **120 volt** hot wires, a neutral wire and a ground wire – that supply two separate 50 amp, 120 volt feeds.

### How long does it take a 10 amp charger to charge a car battery?

If you are using a battery charger, a 10 amp charger will take **4 to 11 hours** to fully charge the battery, a 2 amp charger will take 2-4 days. Of course you don't have to get the battery to full charge to get it to start the car.

### How do you know when a car battery is fully charged?

Fully charged automotive batteries should **measure at 12.6 volts or above**. When the engine is running, this measurement should be 13.7 to 14.7 volts. If you don't have a multimeter to tell you the voltage of your battery, you can do a test of your electrical system by starting the car and turning on the headlights.

### Can a trickle charger ruin a battery?

Leaving a battery connected to a trickle charger for too long **can lead to overcharging**, causing damage to the battery. ... Although they can't recharge a dead battery, they can be used frequently and left connected to a battery without any risk of overcharging.

### Is it OK to leave a battery on trickle charge?

It can take longer if you have a larger battery. You should hook up the trickle charger **10 to 15 hours after a full charge**. However, if you plan to leave your car idle for weeks or months unsupervised, you can leave the trickle charger on. It will safely charge the battery whenever the battery level drops.

### How long does it take to charge a 12 volt car battery at 6 amps?

How long does it take to charge a car battery? A small car battery can be charged in 4 to 5 hours, a mid-sized battery **can be charged in 5 to 6 hours**, and a large car battery can be charged in 7 to 10 hours.

### Does amperage matter when charging a battery?

**No, amps do not have to match**, but the power supply or charger must be able to supply enough amps as required by the device being powered or charged. In practical terms, that means the amperage rating of a power supply or charger must match or exceed that required by the device it is connected to.

### At what voltage will a car not start?

In general, while both the engine and the generator are in the working state, the voltage of the battery should be within **13.7 – 14.2V**. If more, then it is harmful to the battery, if less, then it is not fully recharged.

### At what voltage is a 12v battery dead?

Resting fully charged 12-volt batteries are around 12.8-12.9 volts, and flat dead ones are at **12.0 volts**, so 12.4 volts on a resting battery means it's about 50% charged.

### What voltage indicates a bad battery?

If your battery is reading 0 volts, chances are the battery experienced a short circuit. If the battery cannot reach **higher than 10.5 volts when** being charged, then the battery has a dead cell. If the battery is fully charged (according to the battery charger) but the voltage is 12.5 or less, the battery is sulfated.

### How long does it take to charge a 12-volt battery?

Yes, batteries take time to recharge. It could take hours. A 12-volt battery could take up to **12-24 hours** to charge fully. When recharging your battery, remember that if it gets too hot while you're charging it, you need to stop charging.

### Can you overcharge a 12-volt battery?

A 12V lead-acid **battery won't be damaged by overcharging if the voltage is kept low** and the charging current is less than the Ah capacity. The battery may become overheated if it can put out more current than it can take. ...