How To Test A Battery Isolator: Explained With 5 Easy Steps


how to test a battery isolator

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Do you want to know how to test a battery isolator for your car?

If you’re a car owner, then you know that keeping your vehicle in good condition is important. One of the most important things to keep your car running smoothly is its battery.

When talking about batteries, a battery isolator is one of the most essential tools to ensure that your car battery is working properly. A proper isolator will make sure your main battery doesn’t go down, and if it does, the additional one will take care of it. All you need is to check all the terminals and examine them twice to find out if the device is in a good position.

In this blog post, we’ll teach you how to test a battery isolator. It is an essential piece of equipment if you want to keep your battery healthy and in good condition. So, if you’re interested in learning more about battery isolators, read on!

What is A Battery Isolator?

A battery isolator is a device that allows you to use two or more batteries to power your vehicle while preventing them from draining each other. It does this by allowing electrical current to flow from the charging system to the battery that needs charging, but not back the other way. 

It is especially important if you have a deep cycle battery that you rely on for starting the engine, as well as for powering accessories like lights and winches. Without a battery isolator, the deep cycle battery would eventually be drained by the others, leaving you stranded. There are a few different types of battery isolators on the market, but they all serve the same basic purpose. 

Some are designed for use with a single alternator, while others can be used with multiple alternators. Ultimately, the best battery isolator for your needs will depend on the specific setup of your vehicle.

What Does An Battery Isolator Do?

Before you know how to test a battery isolator, it’s important to know how a battery isolator works.

A battery isolator works in one way. It prevents the failure of any single battery that may incapacitate the whole electrical system of your vehicle. The isolator also ensures that your car’s electric arrangement doesn’t take off all the power from various batteries at the same time.

It is very helpful because if there’s no isolator and the power from multiple batteries drains out, the whole system fails terribly. It can also dangerously affect your car. As a result, the entire battery backup can mess up.

A battery isolator makes sure it doesn’t happen that way.

So, how does a battery isolator work? 

A smart battery isolator works to separate dual batteries from one another to ensure that you are charging your auxiliary battery while driving and protecting your main battery from excessive discharge.

A battery isolator works in the following way: 

  • As the isolator is one way, it never connects with the main battery circuit.
  • You can make your isolator take all the current and use your vehicle lights, accessories, and whatever you want with the additional battery for as long as you want.
  • After the isolator is down, your vehicle will still start the engine, and your other car accessories will work just fine with the main battery system. 
  • Likewise, if the main battery goes down, you can jump off to it and eventually make your vehicle run if you have a battery isolator. This or that, you’ll always get the backup.

How to Test a Battery Isolator – Easy Steps

Testing a battery isolator is not that hard. If you know how a dual battery isolator works, it will be easier for you to understand how to test a battery isolator.

One must check their battery isolator before installing it. As it’s a battery system, sometimes a tiny inconvenience can cause a huge issue. Below I’ve stated some steps to test the isolator as effortlessly as you can.

  • First of all, try to check all the wires that are connected to the terminal of the isolator.
  • After checking it, note which wire is connected to which side. This is important because you have to make sure about the current flow system later.
  • The coach battery, chassis battery, and alternator need to be checked as well. Match it with the guide manual, and you’ll find if they’re at the right place.
  • This checkout phase will help you to understand if your alternative battery has the power to charge the main battery as well as not drawing them when being used.
  • You need to go with the serial while examining the wires. Check thoroughly if all the wires are exactly with the accurate terminal.
  • Be careful about this step as it may cause danger if you’re distracted.
  • Now take the multimeter out and switch it to the arrow diode function.
  • Then, the positive lead from the alternator needs to be taken, and you have to connect it to the multimeter’s positive test probe.
  • After that, you have to connect the other wire from the alternator’s positive side to the battery bank to ensure the electricity flow from one point to the other one.
  • This time you’ll get value from the diode, and it’ll show the flow of the current.
  • Now you have to change the leads of the wire and make sure there’s no flow on the other side. If it shows 0, this means the current is flowing one-sidedly. 

Therefore, it’ll be proven that your battery isolator is okay.

Also, after you’re sure your isolator is good, you can reconnect the wires. But remember that you can’t just disconnect and reconnect all the wires repeatedly, so make sure to review the terminals properly.

If there’s any issue detected, replace it immediately

What Happens When A Battery Isolator Fails?

If a circuit board doesn’t work properly, there’s a high chance your battery isolator may fail. Some damages may happen if it fails, such as:

  • If the terminals aren’t covered properly, it may cause a short circuit or, worst case scenario; a fire explosion may happen.
  • You have to use your isolator depending on capacity. For example, if the capacity is 6000milliamp (which is the highest achieved capacity in batteries) and you use it more than that, the damage can happen. It won’t show immediately, but in the long run, your isolator will become less worthy.
  • Last but not least, smoking cigarettes or another vape where your lithium battery isolator is located might cause a big explosion as the cover of the battery might not take it.

FAQ: How to Test A Battery Isolator

  • Can a battery isolator drain a battery?

No, a battery isolator doesn’t drain another battery life attached to the entire engine system. Instead, it enables redundancy for the entire system with various auxiliary batteries.

  • Why do you need a battery isolator?

You need to have a battery isolator for vehicles that requires more than one battery. This tool helps to maintain sufficient power intact in the main battery to start your engine. Plus, it recharges the other batteries too.

  • Can you charge two batteries with one alternator?

If you’re thinking about a car alternator, it’ll be more than enough to charge two batteries. However, you have to be careful about charging them simultaneously, as one might get charged, and the other can remain uncharged.

  • What are the symptoms of a bad battery isolator?

Well, if your battery isolator has issues, it’ll show the current flow in two ways when a good isolator always does in one way. Then again, sometimes the isolator might show no continuity at all, which can be detected as faulty too.

How Do You Know If Your Battery Isolator Works?

That was all regarding how to test a battery isolator. Now, how do you know if it’s okay?

If your battery isolator is working properly, you’ll get the current flow passing through the single way; the continuity will be shown on one side basically. The wires will be in the proper situation, and the terminals will give the signals matched with your manual (you get with the isolator) as well. 

Last but not the least, try to be safe and secure as much as possible as the wire works are always risky.

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