The car’s battery is what keeps it running. We rarely even think about the battery. We crank the key, start the engine, and drive. But when you find yourself in a situation where you need a new battery, you will learn all the specs fast. One of the most important specs is how many watts are in a 12-volt car battery.
The wattage of the battery is not a fixed value. It is determined based on amperage and wattage. Car batteries are rated for 12 volts, and amperage depends on the type of the battery. To calculate how many watts are in the battery you should multiply the amperage and the voltage. A typical car battery has 45 amps, and when you multiply that by 12 volts, it results in 540 watts capacity.
Several electrical units are used to determine a car battery so that can cause a bit of confusion. Also, not all cars support all car batteries. You need to know what batteries you can use for your car. Stay with us while we divide this topic so you can best understand what to look for in a car battery.
Is A 12-volt Battery Okay for a Car?
Car batteries are rated as 12-volt batteries. But, you should know that the normal operating range of a battery while the engine is running is between 13.7V and 14.7V. When the engine is off, the value drops to 12.6V.
If you think that your car’s 12v battery is having issues, you would need to measure it. For this, you will need a multimeter.
- With the positive (red) multimeter lead touch the positive battery terminal
- With the negative (black) multimeter lead touch the negative battery terminal
- Turn the ignition key, but do not turn the engine on
- Watch the readout on the multimeter. If the value is below 12.2V the resting voltage is weak. You can try to recharge the battery and monitor how it works. In the end, you will probably have to replace it
- If the readout is below 10V you are dealing with a dead battery.
12v Car Battery Capacity
Car Battery Wattage
Power is measured in watts, and unit watts per hour measures the capacity of power moving over time. So if a battery is rated 540 watts it can use that amount of power per hour. Cars that have stronger engines demand batteries with higher wattage ratings.
If your car has a demand of 250 watts per hour, and you have a 540 watts battery capacity, you can run a car for a bit longer than 2 hours.
Car Battery Hours
Car battery capacity rating is measured in amp hours. Classic car batteries have a capacity in the range of 45 to 105 Ah. Higher-rated batteries show that they can store more energy and can last longer between recharges.
While watts per hour measure energy, amp per hour measures in this example battery charge. So, if a battery has 45 Ah it can expel 45 amps in one hour. This way you can calculate how many amps a battery can expel for a certain period.
Why Knowing the Wattage of Your Car Battery Matter
Knowing the wattage of your car battery is essential when buying a new battery. The battery needs to fulfill the electricity usage of the car. The engine draws power and demands a constant energy supply like the rest of the electrical systems. The battery must support the energy usage of all components.
Yes, the battery is constantly recharged, but it still needs to store some amount of power. Every car has a battery rating. If you are not sure which battery to buy, consult the car’s user manual.
How to Calculate Watts in a 12 Volt Car Battery
To calculate the watts in your 12-volt battery you only need to know the amperage rating of the battery.
Amp Hours vs. Watts: What’s the Difference?
The capacity rating of the battery is measured and presented in amp hours. This value tells the driver how much power the battery can store and deliver in a certain time period. We can explain the meaning of amp rating and capacity, in the form of a stamina rating. The amp rating of a battery measured in amp hours (Ah) shows the amount of electrical charge that the battery can deliver in an hour.
The Watts rating of the battery is a broader characteristic that shows how much energy the battery can overall deliver. To determine the watts capacity you need to take into account both the current (amperage) and the battery voltage.
So, amps and watts are closely tied and can help you to determine the capacity of the battery. But, there are key differences. The amps show you the capacity to hold the charge of the battery over time. The watts show the total energy capacity of a battery over time.
What Is the Highest Wattage on a 12-Volt Car Battery?
The typical amperage of a car battery varies between 45 and 105. From that, we can calculate that the wattage capacity on these batteries is between 540 and 1260.
Factors Affecting Wattage in a 12 Volt Car Battery
Temperature
Both extreme high and low temperatures will have a negative impact on battery characteristics and work life. The optimal temperature for an acid battery is between 50°F and 86°F. Temperatures higher than those cause the sulfation of the battery. If the battery is sulfating, that process creates a gray residue on battery terminals. It is often confused with corrosion, but it is far more dangerous.
In extreme cold temperatures, sulfation is not a problem. The problem is the power output of the battery, and its ability to receive a charge. That is why we often have problems starting the car in extremely cold winters.
Age of the battery
An average battery life is between 3 and 5 years. Those originally installed can last a bit longer. But, you should keep an eye on their voltage. Check them from time to time, because with age, batteries lose voltage. Consult with a mechanic when you should replace it.
When the voltage drops below 12.4V when the engine is not running, it is time for a new battery. The worst thing is to wait until the battery is too old, and all of sudden die. You can be in the middle of nowhere with no help in sight.
State of Charge
A battery that is in good condition and is fully charged shows an output above 12.6V. Factors like, temperature, age of the battery, or other physical damages can shorten its life and lower its charge. You may have a relatively new battery, but if the sulfation process is underway you will need to replace it soon. Corroded terminals will also lower the overall charge of the battery.
If after measuring a battery you detect a low charge, and you do not see any obvious damage, then the problem can be somewhere else. When the engine is running an alternator is constantly recharging the battery. If the alternator goes bad, then the battery cannot have a full charge.
Check Out Doing This Will Make Your Car Battery Last Twice as Long:
Tips on How to Choose a Car Battery Based on Wattage
Every car in its user manual recommends a specific type of battery. It needs to fulfill the amps rating, the cranking amps, and the cold cranking amps rating. We already covered that the battery wattage is calculated when you multiply 12 volts by the amp capacity. In the user manual is a recommended amp rating for your car battery. From there you can easily calculate the needed wattage.
Yes, you can choose a battery with a higher amp capacity, leading to a higher wattage rating. But, the car will have problems with charging a stronger battery. It has a starter that can without problems charge a specific battery type. If you add a much stronger battery, the starter will have a hard time charging it. It can also shorten its work life.
So, when choosing a car battery, the best thing to do is to consult with the user manual and the mechanic. You cannot miss it when you have that information.
FAQs
How Heavy Is a 12-Volt Car Battery
A typical 12-volt car battery can weigh between 30 and 45 pounds. When changing your old battery, you should get a new one that has the same or at least similar weight. Heavier batteries will have a negative impact on the vehicle’s performance.
How Long Does a 12 v Battery Car Last?
A 12 v car battery in most cases lasts between 3 and 5 years. Temperature and physical conditions will impact the work life of a battery. Extreme heat or cold can shorten its life. Also, if the battery is damaged, then you will need to replace it sooner.
What Is the Best Way to Boost the Amperage of A 12 Volt Automobile Lead Acid Battery And/or Extend Its Life?
The best way to boost the amperage and extend the life of a 12-volt acid battery is to maintain and use it properly. Here are a couple of tips that can go a long way:
- Check the battery’s water levels. If the level is below the lead plates, add more distilled water. Do not overflow, and add enough water to cover the plates.
- From time to time check the battery terminals. They are prone to corrosion, which impacts their overall performance. To clean the corrosion, use a wire brush or a homemade paste made of baking soda and water. A second option is a premade terminal cleaner that you can buy in any car shop.
- Occasionally check the battery’s voltage. The battery should be always full. If it has a problem with undercharging, it will have a shorter work life. Also note, that sometimes the readout on the battery may show a full battery, but the car has problems starting.
- Try to avoid a complete discharge of the battery. This can happen if the car is not driven for a long time. Try to make a couple of rounds every week or so, so the battery can get to a complete charge.
- Provide good weather conditions. Battery best works between 50°F and 86°F. If it is too warm, keep the car in the shade. If it is cold, try to park it in a relatively warm place.
Final Considerations
Choosing a battery is crucial for the overall work of your car. When you turn the ignition key, the battery sends power to the ignition switch and then to the starter relay. Once the car is running, the battery powers all the modules and sensors that are needed for everyday work.
It is worth knowing that an average battery can sustain between 4 and 5 amps for ten hours. This translates into a 50-amp or 600-watt battery.
You may think that information about batteries is not important, but knowing all the specs will keep you from buying the wrong one. Understanding how many watts are in the battery is easy to calculate once you know how many volts and amps the battery has.
