Almost every internal-combustion engine powered vehicle comes with a 12V DC battery to power the electrical accessories such as the car’s headlights, radio, and AC fans.
The battery is charged by an alternator attached to the accessories belt on the engine. The alternator is designed to regulate a voltage (14.2-14.7V) higher than the battery voltage (12.4-12.8V) and a current higher than what can be drained with all accessories turned on to charge the battery constantly.
What Does It Mean?
The battery saver active message means that the battery has little charge left, so to prevent the car from failing to start on the next start, the vehicle goes into power-saving mode, which turns off most of the electrical accessories in the car to save charge. It means that your vehicle’s battery or alternator can not keep up with the vehicle’s electrical demand.
What Causes Battery Saver Mode?
Battery saver mode is triggered mainly by a decrease in the battery voltage or by continuous discharge from the battery.
It can be caused by a problematic battery, bad battery connections, alternator, or a faulty battery sensor.
I put together a detailed diagnostic procedure to narrow down the probable cause of your vehicle’s “Battery Saver Mode” message from the most straightforward repair to the most difficult one.
1. Bad Battery Connections
Lose battery connections can result in inaccurate sensor reading and intermittent current supply to the accessories. Rust on the battery connections can also lead to similar issues.
Clean your battery terminals with a wire brush and sandpaper if it is rusted or dirty, and tighten them properly so they don’t get loose on pits and bumps.
Also, spray some anti-corrosion spray on the terminals to prevent the terminals from developing any rust in the future.
2. Bad Battery Sensor
The vehicle’s battery sensor measures the voltage and the net current supply to the battery. When the voltage across the battery terminals drops significantly below 12.4V, the message pops up in your dashboard.
The sensor also monitors the net current, which includes the sum of the current drawn from the accessories and the current supply by the alternator.
The message can also pop up in case of a continuous negative current supply to the battery, i.e., when the current draw from accessories exceeds the current supply from the alternator.
It can be diagnosed by cross-checking the readings from the battery sensor with an actual volt and amp meter.
Incorrect installation of the battery sensor can sometimes lead to inaccurate values, which cause the battery saver message to pop up.
3. Bad Battery
One of the leading causes of the battery saver message is a bad battery, which fails to hold significant voltage and charge over time; hence the battery saver mode is triggered.
You can test on your own by monitoring the battery voltage when starting the car with a voltmeter. If your battery’s voltage drops below 10V on starting/cranking the engine, or it’s lower than 12.4V when the engine is OFF, then your car needs a battery replacement.
A battery can also show low voltage because of a failing alternator that is not able to charge it properly. Before testing the battery, make sure the battery is charged correctly to 100%.
Battery health can thoroughly be checked with battery testers available in most car garages. Before deciding to buy a new battery to get rid of the “battery saver active” message, I recommend visiting a car garage to have your battery tested.
4. Bad Alternator
An alternator can stop charging the battery due to a mechanical or electrical issue, leading to this error message.
If the battery saver message has popped up while driving, then the issue is probably a bad alternator or a loose connection.
A bad alternator can be tested on your own by using a multimeter. The voltage across the battery terminals with the engine and most accessories ON shouldn’t fall below 13 volts.
Most mechanics have better tools to test the alternator performance so that you can make an informed decision before replacing it.
How to fix Battery Saver Active?
To get rid of the battery saver active message, you must diagnose the exact issue causing the message to pop up.
It can be a failing alternator, an old battery, a corroded or loose electrical connection, or a faulty battery sensor.
You can narrow down your hunt for the failing component by testing each part, from the cheapest component all the way up to the alternator.
Can I drive my car if the Battery Saver Active light is on?
While not completely dangerous, the Battery Saver Active message should not be ignored. You might drive your car, but depending on what causes this warning message to pop up, you might get stranded. I always recommend not driving the vehicle if any of the warning lights are on.