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Charge the Battery

After unboxing your M400, the first thing you need to do is charge the battery. Let your M400 fully charge before taking it into use for the first time.

The M400 has an internal, rechargeable battery. Use the USB cable included in the product set to charge it via the USB port on your computer.

You can charge the battery via a wall outlet. When charging via a wall outlet, use a USB power adapter (not included in the product set). If you use a USB power adapter, make sure that the adapter is marked with "output 5Vdc" and that it provides a minimum of 500mA. Only use an adequately safety approved USB power adapter (marked with "LPS", "Limited Power Supply", "UL listed" or “CE”).

Do not charge Polar products with a 9 volt charger. Using a 9 volt charger can damage your Polar product.

  1. Plug the micro USB connector into the USB port in the M400, and plug the other end of the cable into your PC.
  2. Charging appears on the display.
  3. When M400 is fully charged, Charging completed is displayed.

Don't leave the battery fully discharged for a long period of time or keep it fully charged all the time, because it might affect the battery life time.

Do not charge the battery when the M400 is wet.

Do not charge the device if the USB port is broken.

Do not charge the battery in temperatures under -10 °C or over +50 °C.

Battery Operating Time

The battery operating time is up to 8 hours with GPS and heart rate sensor. When used only in time mode with daily activity monitoring, the operating time is approximately 30 days. The operating time depends on many factors, such as the temperature of the environment in which you use your M400, the features you use, and battery aging. The operating time is significantly reduced in temperatures well below freezing. Wearing the M400 under your overcoat helps to keep it warmer and to increase the operating time.

Low Battery Notifications

Battery low. Charge

The battery charge is low. It is recommended to charge M400.

Charge before training

The charge is too low for recording a training session.

A new training session cannot be started before charging M400.


When the display is blank, the battery is empty and M400 has gone to sleep mode. Charge your M400. If the battery is totally drained, it may take a while for the charging animation to appear on the display.