In all sincerity, reading a battery charger for the first time can be a bit confusing, especially if you have no guide on how to read it. When I tried reading a battery charger for the first time, I was so confused that I had to call for help. After that time, I can easily read any battery amp meter regardless of the make, size, or shape.
Below, I’ll explain how to read a battery charger like I’m talking to a 7-year-old kid. That way, you will be able to read any battery charger by the end of this article. I’ll also discuss types of battery chargers and safety precautions when charging a car battery.
What Is Amp Metre On A Battery Charger?
The first question that comes to mind when looking at battery charger is what is this meter for? The meter on a battery charger is called an amp meter. It is used to tell how fast the battery is charging.
You can tell how fast a battery is charging by reading the charging rate. I will explain that more in the next section.
What’s The Difference Between Charging Rate And Charge Rate?
When reading a battery charger, you should look at two things—the charging rate and the charge rates. Let me explain.
The charging rate is the amount of voltage that the battery charger is supplying to the battery at a given time. Charge rate, on the other hand, is the amount of time it will take for the battery to be fully charged. I’ll explain this more when reading the battery charger below.
But with this in mind, if you want to purchase a battery charger, get the one that is appropriate for your battery. If the charging rate is too high, it may overheat and damage the battery. If it is too slow, it will take a longer time to charge the battery from 0 to 100%.
Types Of Car Battery Chargers
Car battery chargers charge batteries at different rates. Some are faster than others. While some charge faster than others, it is important to use the appropriate charger for your battery to avoid overheating and explosion.
Though high-quality chargers have safety features like voltage regulators and automatic shut-off, don’t abuse these features. Always stick with appropriate chargers for your specific battery.
Let’s see the types of car battery chargers available on the market shelves.
2 amp battery chargers
Just like the name suggest, 2 amp battery chargers send in 2 amps voltage to your battery every hour. As a result, they take a long time to fully charge your battery. They are often called trickle chargers or battery maintainers. These chargers provide just enough power to keep your batteries charged. Since they charge at slow rate, they are best for small batteries, such as snowmobiles, motorcycles, lawn garden tractors, etc.
It will take 24 hours to fully charge a drained 48 amps car battery. A typical car battery is 48 amps. 48 divided by 2 you get 24 hours. The higher the battery amps, the longer it will take to charge it with a 2-amp charger.
10 amp car battery charger
The higher the battery charger amp, the faster it will take to charge a dead battery. Technically, it will take 4 to 11 hours to fully charge a depleted battery with a 10 amp battery charger. Most completely dead batteries take a fast charge and the charging will become slow after the first few hours.
40/50 amp car battery charger
40/50 amp battery chargers are called engine starters because you can use them to use a car with a completely dead battery without jump-starting it. With a 40 amp charger, you can charge your battery quickly and effectively within minutes.
How To Read A Battery Charger In Four Simple Steps
When reading a battery charger, there are four things you should do. You should connect the charger to the battery, calculate the charge rates, calculate the percentage charged, and check the green and red triangles.
Connect the charger to the battery
First thing first. Connect the black cable to the negative battery terminal and the red cable to the positive terminal. If you connect them properly, the needle on the charger meter will move to show you the current percentage of the battery. And as the battery is charging, the needle will keep moving in proportion to the current battery percentage.
Calculate the charge rates
The next thing you should look at is the charge rates. Below the percentage on the charger meter, you will see numbers 0,2,4,6,8,10 and 12. These are the charge rates. Each of them indicates how many amps the charger is sending to the battery. As the battery is charging, the needle on the charger meter will move between those numbers as the battery charges.
If you were asking, What do the numbers mean on a battery charger, now you know.
Some chargers have multiple charge options, such as 2 amps, 10 amps, and 50 amps. However, I advise you only use 50 amps when your car battery is completely dead and you want to jump-start your car.
Calculate the percentage charged
You will see 0, 25, 50, 75, and 100% on the amp scale. If the meter needle points at 25%, the battery is 25% charged. When charging, the meter needle will keep moving toward 100% to indicate the current battery percentage. That is, the needle will keep moving from the left to right across the dial.
If the battery is extremely low, the charger will be sending higher voltage to the battery.
As the battery percentage increases, it will start sending lesser voltage to it. For instance, if you are charging a dead battery with a 10 amps charger, the needle will start pointing at a 12 charge rate. Meaning it is sending 12 volts of power to the battery.
How do you tell when a battery is fully charged on a battery charger? If your battery charger points at 0 amps when charging, it is fully charged, and the charger has stopped sending voltage to the battery.
But what should a 12-volt battery charger read when fully charged? When fully charged, a 12-volt batter will read 12.6V. However, a slight decrease to 12.5V is okay.
The green and red triangles on the meter
There are two red triangles on the meter. Each denotes the charging rate you have chosen. For instance, if you switch your charger to 10 amps when charging a dead battery, the needle will start reading from the red triangle on the left.
If you switch it to 2 amps, the needle will start reading from the red triangle on the right. The meter needle moves from left to right irrespective of the charging option you choose. As the battery percentage increases, the meter needle will move into the green zone.
Safety Tips
When dealing with car batteries, safety should be your number one priority. Despite they are properly sealed, car batteries can release dangerous chemicals due to chemical reactions. Here are a few things you should keep in mind when charging your car battery.
Always stick to your battery manufacturer’s instructions for precautions and specific charging recommendations
Only use chargers that are compatible with your battery size and type. If you use a high-quality charger with multiple charging options, switch it to the recommended option for your battery type and size.
Clean the battery terminals before connecting the charge to ensure a stable connection and to prevent electrical issues.
Inspect the battery terminals and charger connectors for corrosion and damage. Damaged connectors will result in poor charging and electrical issues.
Do not charge in extreme temperatures. It can affect the charging duration and the battery’s health.
Keep the kids and pets out of the charging area.
If you see smoke coming from the battery or notice anything unusual, disconnect the charger and see if you connect it properly.
Final words
At this point, you can confidently read an analog battery charger and tell what each parameter means. The ammeter shows the percentage of the battery current and the amount of time it will take to recharge the battery. The meter needle should move slightly towards the right as the battery is charging. A constantly bouncing needle means the battery is defective and you should replace it after the first few minutes.
To sum it up, battery chargers come in different sizes and shapes. A charger may have more than one gauge or more than one needle, making it a bit confusing at first to read. But with the instructions in this article, you can easily read any battery charger.
