Why is my CTEK battery charger blinking?
26 November 2025
When you connect your CTEK battery charger to your vehicle battery and turn on the power you may notice a light blinking on the battery charger. Various chargers have their own different appearances but most CTEK chargers – such as the MXS, CT5, NXT, MXT and PRO25 models – have this light.
If you are wondering what the light is and why it is blinking, you have come to the right place for the answers.
This is the power light and when it lights up it means you’ve connected to a power outlet and there is power going into the charger. But if it’s still blinking after two minutes, it means the battery charger is getting power but it cannot detect the battery you are hoping to charge.
If this happens, please first check your connection to the battery. You are looking to see if the clamps are connected properly. If you have connected the clamps correctly and the charger still can’t detect the battery, the voltage in the battery may be too low. Because of the charger’s built-in safety features, the battery needs to have a charge level of at least 1.5 – 3V, depending on the charger, for the charging program to start.
If your charger has Supply mode, you can use this to bring your battery up over the safety level, then change to regular charge mode and charge the battery as usual.
Just activate the Supply mode, leave it on for about a minute and then switch to the charging mode. Remember though, that when activating Supply mode the clamps are no longer spark free, so please be careful when connecting them and do not touch the clamps together.
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