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Polar M400 Watch Battery Replacement

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Time Required: 9 - 10 minutes
Difficulty: Moderate
Polar M400 Watch Battery Replacement

Introduction

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This guide will teach someone how to take out the battery in the Polar M400 and replace it with a working one. A damaged battery could be due to lack of charge or submersion in water more than 30 meters. It could also be due to battery age and various malfunctions. Over time, excessive and wear can lead to battery damage. The Polar M400 has an internal, rechargeable battery. You can charge the battery over 300 times or two years before a notable decrease in its capacity. The number of charge cycles also varies depending on use and operating conditions. Once the battery is replaced, follow local waste disposal regulations and do not dispose of this product as unsorted municipal waste.

What you need

Parts

Tools

    1. Polar M400 Watch Battery Replacement, Wrist Strap: step 1, image 1 of 1
      • Insert a standard paper clip into the holes on both sides of the watch that connect the watch's face with the wrist strap.

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    2. Polar M400 Watch Battery Replacement: step 2, image 1 of 2 Polar M400 Watch Battery Replacement: step 2, image 2 of 2
      Tool used on this step:
      Tweezers
      $4.99
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      • Apply an upward pressure to the holes until the locking pins release.

      • Use precision tweezers to remove the pins that connect the face with the strap.

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    3. Polar M400 Watch Battery Replacement: step 3, image 1 of 1
      • Once the pins are released, the old wrist strap should snap off.

      • Simply lock the new wrist strap into place.

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    1. Polar M400 Watch Battery Replacement, Battery: step 4, image 1 of 1
      • Use the T5 head on the iFixit screwdriver to unscrew the four screws on the back of the watch’s face.

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    2. Polar M400 Watch Battery Replacement: step 5, image 1 of 2 Polar M400 Watch Battery Replacement: step 5, image 2 of 2
      • Gently remove the backing from the watch.

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    3. Polar M400 Watch Battery Replacement: step 6, image 1 of 2 Polar M400 Watch Battery Replacement: step 6, image 2 of 2
      Tool used on this step:
      Tweezers
      $4.99
      Buy
      • Use tweezers to gently pry the golden sensor away from the battery.

      • Remove battery using the plastic opening tools.

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Conclusion

To reassemble your device, follow these instructions in reverse order.

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16 other people completed this guide.

Nicholas Sanders

Member since: 09/28/17

543 Reputation

2 Guides authored

25 Guide Comments

Hello, thanks for the details !

The most tricky part: find the right spare part. I can’t find a replacement battery that could fit the original dimensions with reasonnable capacity.

Do you have any lead?

Vincent - Reply Share

In case if anyone is still looking for the spare part I have just replaced my M400 battery with this one: https://www.aliexpress.com/item/10050045...
Replacement instructions were detailed enough to get my watch to work again.

Roman - Reply Share

Bonjour

Pourriez-vous m’indiquer ou je peux acheter une batterie compatible ou originale

Merci à vous

ducellier - Reply Share

where can i buy a batery for my polar m400? Link please. Thanks

lsmi_21 - Reply Share

Once the battery is changed, the M400 does not work. Do you have to press any combination of keys?

lojobis - Reply Share

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