Why is my eBike battery flashing blue? (5 Fixes)

There is nothing more annoying about an electric bike than a non-functioning battery.

I think that having a problem with the battery is like turning an electric bike with all its speed and potential into a regular bike

Therefore, in this post, we will explain one of the battery problems that lead to the bike stopping, which is the presence of blue light and the inability to charge.

Why is my eBike battery flashing blue?

As a general rule, the blue color in the battery means that the battery is not able to get enough electrical current or output voltage to the motor.

There are five main reasons that lead to this problem.In the next section, we will explain each cause and how to fix it.

1-Cold or Freezing weather.

Inside the electric bike battery, there are cells with a capacity of about 3.7 volts and there is a chip called the BMS

This chip is responsible for regulating the entry of electrical current into all battery cells

Among the ways to protect the battery is that if the BMS senses that the temperature inside the battery is less than 0, it will turn off the electrical current and will give you a blue signal.

FIX: In order to fix this problem, insert the battery to a suitable temperature (room temperature) and leave the battery for about two hours. Then try to charge it again.

If there is no defect in the battery cells, it will work normally.

2-Low Battery voltage \Dead Battery.

One of the most common reasons for the appearance of blue light on the electric bike battery is the severe lack of charge and low voltage inside the battery cells.

This problem often occurs after storing the battery for a long time without use, especially if the correct methods of storing the battery are not followed.

How Do You Discharge An Ebike Battery For Storage? (Solved)

The reason for this is that the battery puts out a certain amount of voltage during storage, and if the storage period increases and the battery is basically empty, then most of the time it will appear blue

Repair: Try to charge the battery. If the battery does not accept charging in this case, it is preferable to measure the voltage. If the voltage is low, less than 20 volts, it is better to go to the battery repair shop because it will help you charge the battery using a small charging source as an attempt to revive the battery again

For more details on reviving the battery, see this post.

How Do You Revive A Dead EBike Battery? (Explained)

3-Battery to Motor connection cable issue.

If you weren’t trying to charge the battery in the first place and you find the ebike stopped working or the assistance from the motor became less and the blue color appeared on the battery.

This means that there is a problem with the connection between the motor and the battery.

In most cases, this problem is the result of a cut in the cable connecting the motor to the battery, or a break in the internal pins.

FIX: In this case, you can change the cable, or if this is not possible, you can solder the cable or change the plug.

4-Wall socket Issue.

Sometimes the cause of the blue color is not a problem with the electric bike or the battery, but it is in the wall socket

The reason for this is that if there is a weakness in the electric current entering the battery, the battery will be given a blue color to tell you that there is a problem with the current.

FIX: You can change the charging source to any other socket, preferably in a different place, because if it is a problem of weak current in one of the sockets, then most of the sockets in this place will have the same problem

5-Damage Charger.

One of the problems that the blue light appears on the battery is a problem with the charger, and the problem here is the weak current entering the battery due to damage to one of the internal components of the charger or the external cable.

You can check out this post that explains in detail how to test the battery charger.

How Do I Test My Electric Bike Charger? (Beginners Guide)

Fix: Change the charger or its cable.


As a general rule, the electric bike battery flashes blue, an indication of low voltage, which occurs as a result of trying to charge in very cold weather, the battery has completely drained, or an issue in the electric current.

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