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The Best OBD Scanner for Diagnosing Battery Issues

By Joe Ballard
Published on September 24th, 2024

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When was the last time you thought about your car's battery? If you're like most people, as long as your vehicle starts and runs normally, there is nothing to worry about, right? Well, maybe not, because sometimes the battery will fail suddenly (personal experience here), and sometimes the decline is gradual over time. In either scenario, it is a good idea to periodically check the battery status with an OBD scanner to identify potential issues before you are stranded on the roadside.

The Best OBD Scanner for Diagnosing Battery Issues

In this article, I will explain what a battery is, how long it typically lasts, the warning signs of a failing battery, and how to diagnose and prevent potential problems.

How does a battery work?

Simply put a battery stores electrical energy that is later used to power your vehicle's electronics. In a modern vehicle loaded with electronics, the battery is critically essential. The battery's design has mostly stayed the same over the past 100 years. It is still based on using lead plates and Sulfuric acid (lead acid) to generate 12 volts. Even the charging system that maintains the battery voltage at 12 volts has stayed the same. This is a real example of "if it ain’t broke, don’t fix it”.

Most modern batteries are sealed units, reducing the amount of electrolyte (sulfuric acid) lost during the charging/discharging cycle. This type of battery lasts significantly longer than those produced 10 – 20 years ago, providing a reliable power source for your vehicle. However, it's important to remember that no battery will last forever. Over time, the constant charging/discharging will cause the lead plates to deteriorate to a point where the battery will no longer hold a charge and will need to be replaced.

All vehicles, whether gas-powered or EV, use a lead-acid battery to power the electronics. I don’t need to tell you that if your battery fails, you cannot go anywhere due to your reliance on this simple power source. But here's the good news: You can easily avoid this situation by investing in an OBD scanner. With this tool, you can run periodic tests on your battery, ensuring its health and your peace of mind.

A lead-acid battery has a different life span based on the job it is required to perform in the vehicle. Here is a breakdown of the useful life of a battery based on the application and environment (heat is a killer):

Conventional gas-powered vehicles that use the battery to start the engine and power all electronics will last about 3 to 4 years.
An EV vehicle that relies on the battery to power the electronics (no gas engine) will last about 5 to 6 years.

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What are the warning signs of a weak battery?

For a lead-acid battery, the symptoms of potential failure include the following:

The engine turns over slowly
Dim or flashing headlights
The Check Engine Light or battery warning light comes on
The battery is more than three years old
One or more of your car's accessories are malfunctioning (radio is at the top of the list)

It is important to watch for any of these warning signs, but if you are a DIYer, you can use your OBD scanner to diagnose an issue with your battery proactively. Using my Mazda Miata as an example, I connected my Innova 5610 scanner and RepairSolutions2 app on my iPhone to run the Battery/Alternator Monitor test. Although this vehicle does not have a lot of sophisticated electronics, the battery is located in the trunk, so the battery cable has to go the whole length of the vehicle to reach the starter. Because of the length of the cable, it is crucial to ensure that the battery does not show any signs of weakness.

Innova 5610 paired with the RepairSolutions 2 app

When I performed the Battery test using the Innova 5610 OBD scanner, the battery tested BAD. I was surprised by this result as I have not experienced any problems starting the car. I also performed the Alternator Monitor test, and the result was GOOD, meaning that the battery was being charged, so the battery must have reached its end of life and should be replaced.

Key Takeaways

Diagnosing a weak battery is a pretty straightforward DIY task. It involves using an OBD scanner and visual clues to tell you much about your battery status. In addition to the warning signs, here are a few visual clues that you can check out under the hood:

The measured voltage is lower than 12Volts
The fluid level in one or more battery cells is low
The battery case looks bloated
There is a leak in the battery
The battery terminals are corroded
Rotten egg (sulphur) smell
Rattling or grinding sounds coming from the alternator

The main things that will cause a battery to go bad include but are not limited to the following:

The battery is more than 3 to 5 years old – if you make it to 5 years, then you are lucky, but now is the time to replace it
Extreme heat or cold temperatures – the warmer the weather, the faster the battery will run out of juice
Irregular vehicle use, such as short trips or parking the vehicle for extended periods - if the battery does not get fully recharged, the battery could go dead
Irregular or poor vehicle maintenance - if the battery is not being checked periodically to ensure that it is fully charged and does not exhibit any visual clues of weakness, then bad things can happen

The typical replacement battery cost will depend on the vehicle type and recommended power rating. For my Mazda Miata, the repair range to have it done by a service center is from $254 to $300. If I purchase the battery from the auto parts store, I can do it myself for about $184.

Conclusion

If you notice any potential failure warning signs associated with your battery, you need to take action as soon as possible. In most cases, a battery may not fail all at once, although this is not true in every case. If you observe any warning signs of an imminent failure, you will usually have some time to react. If you ignore the warning signs, you may, at best, get stranded, or worse, you could experience a complete failure of all your vehicle's electronics. Using your OBD scanner to periodically check your battery status or get it checked by an experienced service technician is always a good idea. Remember, an ounce of prevention is worth a pound of cure when it comes to the vehicle battery, so don't ignore the warning signs.