Car Batteries

How To Read A Battery Charger Amp Meter?

Mike Cross
Updated Oct 28, 2021

When charging a battery, it is important to know how many amps are going into the battery. To do this, you can use the amp meter on the charger.

After reading this article, you will know how to read a battery charger amp meter properly. We will break it down into simple steps, so anyone can read their meter after reading this article.

How to read a battery charger amp meter?

How To Read A Battery Charger Amp Meter?

Connecting Battery Charger

Before being able to read the amp meter on your battery charger or battery tender, you must be able to connect it. The first step to connecting it is to open the car hood and disconnect the battery from the car.

To do this, you just remove the positive and negative leads from the diode. If you don't know how to disconnect these leads, it isn't that hard.

First, you will need to get a screwdriver for most cars or sometimes a socket. You then just loosen the screw but don't remove it all the way. This loosens the clamp at the end of the lead.

Once the clamp is loose enough, you just take the leadoff. You then do the same to the other one. It is best to disconnect the positive first and then the negative. Also, while disconnecting these make sure the car is off, and the key is not in the ignition.

Connecting battery charger

Once you have the leads of the diodes, you just have to connect the battery charger. Depending on the type of battery charger you have might determine how you do this. Most chargers have clamps of some sort though.

All you do is take the wires with the clamps on them, they will probably look like jumper cables, and then you hook the clamps to the post. The positive one needs to go to the positive and the negative needs to go to the negative.

If you don't know which is which then just look at the post and the positive will have a plus sign on it. If you can't tell the clamps apart, then they should have a sign on them as well. A general rule of thumb though is that the positive clamp is red and the negative is black.

Reading the Meter

 Charging car battery with electricity trough jumper cables

Now that you have the battery charger connected it is time to read the meter. To read the meter, you will have to plug the battery charger in and then turn it on. When you turn it on the needle on the meter will move.

If you have the charger set to ten amps, then the needle will move to that point. As the battery charges the needle will drop. Once the needle is down to about half of whatever amount the charger is set to, then that means it is fully charged.

Sometimes there may be more than one needle. The needle that moves to the amount you have it set to is the one that is telling you how many amps the charger is putting out. The other needle is telling you how much charge the battery has.

If yours has two needles and they work this way, then you know the battery is fully charged when the needles are on top of each other. Reading the meter on your battery charger is that simple.

Multiple Scales

One last thing to know is some battery chargers also have two scales on the amp meter if it can output at different amps. For example, it is not to uncommon to see a 2amp scale and also a 10amp scale.

They are normally in different color numbers. When looking to see where the needle lines up you need to make sure you are reading the correct number for the output. This way you will get an accurate result. Make sure you have the dial set to what you think you have it set to.

Multiple scales

Sometimes the know can get moved or a switch flipped when moving your charger around and that could lead to you charging at a different amp then you though or you reading the wrong scale.

Reading Digital Meters

Some newer or more expensive battery chargers may have meters on them that are digital. This is nice because it makes them easy to read, but can be confusing because you might not be reading the right thing.

To read the amp output of your battery with a digital reader you will need to make sure it is on the right setting. To do this you can push the button on the control. This will cycle thru the different read out options that yours has.

Some other ones besides amp might be the volt output. To make sure that it is the amp output that you are reading you can click the button and ccle thru till you see it say amp on the screen with the number.

This will make it so you know you are reading the right thing. If it says volt or something else you will need to click the button and go thru the different numbers till you are at the right one.


Reading a battery charger amp meter isn't all that hard. All you have to do is make sure you are looking at the right scale and when you have it connected you look at the number that the needle is pointing too.

The number is how much charge the charger is putting off to the battery. When the battery gets full it won't be pulling as much charge. This means if charging at 10 amps the needle may only be at 2 amps and if charging at 2 amps the needle may have barely moved.

Reading digital scales is even easier because you just have to read the number displayed and make sure that it amps being displayed. After reading this you should be able to read your battery charger amp meter and know when your battery is done charging.

Mike Cross
Life is too short to drive with stock audio

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One comment on “How To Read A Battery Charger Amp Meter?”

  1. Are you crazy?😜 Never remove the positive connection first. If your wrench might touch a metal part of the vehicle it is a DANGEROUS dead short.😢
    I can't believe anyone would advise that. Removing the NEGATIVE cable if your wrench might hit a ground point no damage

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