Polar M400 Battery replacement

"Battery change would be easy if you could find a battery. A T5 star driver is needed to open the watch and the battery is stuck to the bezel, easily removed.

After many hours trying to find a battery (via AliExpress) I gave up. There are two issues:

1) The Polar battery is a lithium polymer (LiPo) 352826 that is not available. You could choose a smaller size such as a 352424, but you'll get lower mAh rating.

2) There are leads on the 352424 and a power regulation circuit board as in the image below. The Polar battery has a bare plastic contact bar with two large contacts. You'd have to modify the power regulation circuit to remove components and leave just the contacts. I tried that modification with another battery and it seemed it would work.

If you choose the smaller battery it would cost ~ $10. I measured the case and bought a battery via AliExpress, but the vendor lied about the size; he took a battery that was approximately the size requested and stuck a label on it that said a 362927. The battery was actually 403124, far too large to fit the watch. A 362927 battery would be 3.6mm x 29mm x 27mm, with a tolerance of ~+/- 5%.

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Communication from Polar:

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We usually do not send fixed prices as the issue can be different than expected and the Tech can find something else wrong. However, at best, a battery change without tax or shipping would be $24.95.

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To start the process, please register your repair online at the link below. Include a copy of the registration or the confirmation email with your product. Include details regarding the issue(s) you are experiencing. Also it is recommended to send in the complete product set (watch, heart rate sensor, strap, cable, etc.) so that we can ensure all devices are working properly. Please include a copy of your proof of purchase.

https://service.polar.com/service/PSCSPr...

Please feel free to contact us if you need further assistance. We may be reached by E-mail, Livechat, or our toll free line by clicking on the link below.

http://www.polarusa.com/us-en/support/co..."

"Found this alternate battery as a possible fit :

LP332726

3.7V 150mAh

3.3mm x 26mm x 27mm

http://www.lipolbattery.com/lithium%20po...

I have not even opened my M400, let alone bought or tried this battery!

Does the M400 use the wired connector or does it have battery contacts?"

"Hi,

When you open the Polar M400 watch you will find four 000 (triple zero) size Phillips screws holding the electronics board. Removing those enables you to remove the electronics board. Doing so, you will find a separate USB connector for data exchange and charging. In my watch the USB connector stopped working and therefore the watch is dead. This happened after two years of use. I am now looking for a replacement. If someone tells me how to upload photos, I could offer photos of the opened unit.

-- AM"