{"id":5086,"date":"2026-08-30T05:50:35","date_gmt":"2026-08-29T20:50:35","guid":{"rendered":"https:\/\/donguri3.net\/server-tech\/earphone-lipo-repair-400909-2\/"},"modified":"2026-08-30T05:50:36","modified_gmt":"2026-08-29T20:50:36","slug":"earphone-lipo-repair-400909","status":"publish","type":"post","link":"https:\/\/donguri3.net\/en\/diy-repair\/repair-pc-hardware\/earphone-lipo-repair-400909\/","title":{"rendered":"[Earphone Repair] I tried replacing the battery in a rare cuff-style earphone myself [LiPo 400909]"},"content":{"rendered":"

Today, I’d like to share the story of repairing a rather uniquely shaped cuff-style earphone<\/strong>. Since most commercially available wireless earphones never fit my ears properly, this unusual design has been an absolute lifesaver for me.
\n\"\u30ab\u30d5\u30b9\u578b\u30a4\u30e4\u30db\u30f3\"<\/a><\/p>\n

However, recently, only the right earphone started giving a low battery warning just about 30 seconds after turning it on<\/strong>… Since I hadn’t changed how I used or charged it, it seems the battery’s lifespan had finally come to an end.<\/p>\n

\n

Disassembly Revealed a LiPo Battery<\/h2>\n

After carefully taking the earphone apart, I confirmed that a small lithium-polymer (LiPo) battery<\/strong> was housed inside.
\n\"\u30ab\u30d5\u30b9\u578b\u30a4\u30e4\u30db\u30f3\u306e\u5206\u89e3\"<\/a><\/p>\n

The label stamped on it read “400909<\/strong>“. While this size is a bit uncommon, searching on AliExpress showed they were being sold for less than 500 yen each<\/strong>.
\n\"Lipo\u30d0\u30c3\u30c6\u30ea\u30fc400909\"<\/a><\/p>\n

\n

Replacing the Battery Myself! The Key Watch-Out Is “Heat”<\/h2>\n

Once the ordered battery arrived, I immediately started the replacement process.<\/p>\n

The battery is of the type that is soldered<\/strong> directly to the circuit board. LiPo batteries are sensitive to heat, and excessive heating carries the risk of expansion or fire<\/strong>, so I proceeded with the soldering work carefully while keeping a close eye on temperature management.<\/p>\n

\n

Replacement Successful! The 30-Second Warning Is Gone<\/h2>\n

After the replacement, I reassembled everything as it was and turned the power on…<\/p>\n

That pesky low battery warning that used to pop up after 30 seconds completely disappeared!<\/strong><\/p>\n

The battery life for both the left and right sides returned to roughly the same level, and I can now use them comfortably just like before. The battery replacement worked like a charm.<\/p>\n

\n

Was the Old Battery Slightly Swollen?<\/h2>\n

Looking at the removed battery again, the surface felt somewhat plump<\/strong>, or at least it seemed that way… While it wasn’t a case of severe swelling, there is no doubt it had degraded from long-term use.<\/p>\n

\n

Conclusion: Keeping Your Favorite Earphones Alive Longer<\/h2>\n

These cuff-style earphones are hard to replace with other off-the-shelf products. Buying a new pair might have been impossible to find, but I successfully extended their life by replacing the battery<\/strong>.<\/p>\n

If you are also struggling with degraded earphone batteries, checking the size and structure of the battery might just mean you can repair it yourself much more easily than you think<\/strong>.<\/p>\n

\n

That concludes my account of repairing a uniquely shaped pair of earphones on my own<\/strong> this time around.<\/p>\n","protected":false},"excerpt":{"rendered":"

Today, I’d like to share the story of repairing a rather uniquely shaped cuff-style earphone. Since most […]<\/p>\n","protected":false},"author":4,"featured_media":1725,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_locale":"en_US","_original_post":"https:\/\/donguri3.net\/?p=1722","footnotes":""},"categories":[1165],"tags":[434,623],"class_list":["post-5086","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-repair-pc-hardware","tag-aliexpress","tag-623","en-US"],"_links":{"self":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts\/5086","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/users\/4"}],"replies":[{"embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/comments?post=5086"}],"version-history":[{"count":1,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts\/5086\/revisions"}],"predecessor-version":[{"id":5089,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/posts\/5086\/revisions\/5089"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/media\/1725"}],"wp:attachment":[{"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/media?parent=5086"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/categories?post=5086"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/donguri3.net\/wp-json\/wp\/v2\/tags?post=5086"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}