If you have owned a car for a fairly long time, you must have seen the start/stop, not ready battery charging sign at least once. Now, this does come off like a warning sign, whereas, in reality, it’s nothing but a simple advisory sign.
Some simple issues, like worn-out cable, damaged battery, or alternator cable, causes it to pop. Here, we have tried to pinpoint some of the most common reasons behind this issue and a few simple ways to fix them.
So, let’s get started.

Start-stop Battery Charging Sign
Before getting into the causes and fixes, we’d like to give you an idea of what the start-stop not-ready battery charging sign actually means.
Because a huge number of new car owners don’t even understand the exact meaning of this sign, this is why a majority of the time, they take this as if there is something wrong with the car and get panicked.
The start-stop battery is rechargeable and delivers power to your car when the engine is turned off. It’s also called ESS, which means energy storage system.
Most of the smaller electrical components in the car are powered by the ESS. The ESS charges itself when the car is working and generally takes about 40- 45 minutes of driving to charge it fully.
This stored charge is later used to automatically start or stop the engine when you are not driving it.
But often, the ESS is not charged to full and requires some time to fill back up. That’s when the start-stop not ready battery sign pops up.
So it’s more like a recommendation to give it some time to finish charging itself.
Common Causes of Start-Stop Not Ready Battery Charging
Usually, this issue happens for 6 common reasons.
Cables Malfunctioning

The first reason is weak or faulty cables. Sometimes the cables that charge the auxiliary battery may not be plugged in properly, which causes it to charge slower than usual.
Also, the cables might be damaged because of the constant battery fumes leading to corrosion. This incident may also prevent the voltage from getting to the auxiliary battery.
In both cases, the battery will take much longer to recharge. And as a result, it will show the “start-stop not ready battery” sign on display.
Ignition Module
An ignition module can also cause the battery charging sign. The best way to make sure is to unplug the spark plugs one by one and check the respective booting time of the engine for each case.
Taking less than 10 seconds hints at malfunctioning modules, and you’ll need to resort to new ones.
Damaged Alternator

What if the auxiliary battery and cables work just fine, but the battery charging sign is still on whenever you start the car? A faulty alternator is probably the reason for this.
The alternator basically works as a connecting point between the auxiliary battery and your car. It feeds the battery with electrical voltage from the combustion energy of the fuel.
Besides, they also play a passive role in running the electrical components by supplying the necessary voltage. But like any other automotive parts, they can also get damaged for various reasons.
The diodes located on the alternator rectifier pass the electrical voltage. Short circuits in these lines will mess up your car.
There are also common issues like overheating, whether from hot weather or overuse of the vehicle, which can cause potential damage.
So, when you have a faulty alternator, it means enough voltage is not passing to the auxiliary battery to charge it. And the result is the start-stop not-ready battery charging sign.
Auxiliary Battery Not Charging

The auxiliary battery plays the most important role in delivering power to the car when the main battery is low on power. And like any other battery, it’s not uncommon for them to be damaged.
Several reasons can damage the auxiliary battery, like leaving the car engine running for a long time. We’re talking about enough time to overheat the system.
This can potentially damage the battery cells leading to electrical malfunctions. The resultant electric shock may even completely ruin the battery.
Most of the time, when the auxiliary battery is damaged, either it can’t accumulate enough charge to boot up the engine or the charge drains too fast, so there’s not enough voltage when necessary. Correspondingly it will keep showing the not-ready battery charging sign.
Terminal Issue
You can also face this problem due to issues with the alternator terminals. This one also restrains the voltage from passing through into the auxiliary battery. The ESS system gets affected and correspondingly takes a much longer period to get charged.
Rusting at the terminals is a common reason why they get damaged. This is somewhat inevitable since it is in constant contact with battery fumes.
The moisture content of the surrounding environment also contributes to this issue.
Faulty Main Battery

The main battery has a passive effect on causing the start-stop not ready battery charging situation. Most issues are related to the main battery draining too fast. As a result, the ESS system of the car gets affected.
Even if other problems are damaging the battery, you can easily detect them from clear visible signs like leaking from the battery, voltage dropping significantly, cranking, etc.
Also, due to the power shortage, the car will draw more power from the auxiliary battery causing it to drain fast as well.
While this happens simultaneously, the auxiliary battery is low on volt most of the time, hence the start-stop, not ready battery charging sign.
How to Fix It
With little to no experience, you can fix the issue yourself by considering the following suggestions.
Cable Replacement

Fixing or replacing faulty cables is probably the easiest solution here. It’s just like changing or replacing any cable in electronic components.
The first step is to keep the engine running and make sure the battery has power. Then just get a new cable that is compatible and plug it in the place of the old cable.
In some cases, the issue might be because of weak or loose cables. So, make sure the cables are plugged in perfectly. If they still don’t function well, then we can be sure that the cables are damaged, and you will have to change them altogether.
Changing Alternator
Problems with the alternator can be fixed as long as it’s detected quickly.
Some servicing in the damaged parts can effectively fix the issues that are causing the warning sign to pop up.
But if the problem is left alone long enough, it may spiral into even bigger problems and permanently damage the alternator. In that case, you’ll have to replace it altogether.
Changing the Battery

While other problems are generally easily fixable, problems with the main battery are hard to resolve. They also tend to break down again in a few months, even when fixed.
If the battery is, in fact, the root of the problem, whether it be the main battery or the auxiliary battery, the better advice would be to replace them with a new one.
The battery varies from car to car, so get professional help if you are not familiar with the whole battery-changing concept. You can also get some basic ideas from your car’s manual.
Fix the Terminals
Terminal issues are fairly easy to detect and fix since you can see the rust with the naked eye. You can scrape away the rust with a screwdriver.
If the problem is still not solved, they are most likely to be permanently damaged, and you’ll have to install a new one.
Frequently Asked Questions
How long does it take to charge the start/stop battery?
The charging specifically depends on the size of the battery. Approximately it takes about 30 to 40 minutes to charge fully.
Can the start/stop sign go away on its own?
Yes. A common case of the auxiliary battery not charging fully is that you don’t drive enough to get it to full charge. In this case, driving around a little more until it’s properly charged will solve the problem.
Conclusion
Overall, Start-stop not-ready battery charging sign shouldn’t be a concern if you know the reasons and how to fix them.
Besides faulty cables, damaged batteries, or alternators, there may be other causes. Seek professional help if there is something out of the ordinary, and it shouldn’t be a problem.
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