Check your belongings not to leave in the car in summer🚗
Do you leave your smartphone or mobile battery in the car in the summer?
When you get out of the car, take the lithium-ion battery-equipped products you brought with you, such as smartphones, mobile batteries, wireless earphones, portable fans, portable game consoles, digital cameras, notebook PCs and tablets. This is the easiest solution.
📌 What is "124"?
According to NITE, 124 incidents involving lithium-ion battery-equipped products reported to NITE between 2021 and 2025 occurred in vehicles, including 49 incidents involving mobile batteries.
However, this is not "124 cases caused only by high temperature exposure in summer." It is a total of car accidents including accidents during charging and using.
🌡 sunshade alone can not prevent it
In JAF's limited experiment, under conditions of 35 ° C outside air, minivan, and 4 hours from noon, the black car without measures recorded a maximum of 57 ° C inside the car and a maximum of 79 ° C on the dashboard.
The maximum temperature in the car was 50 ° C even with the sunshade installed, and 45 ° C even with the window opened 3 cm.
While not all cars, neighborhoods and days have the same temperature, sunshades and window openers cannot be the only safety standard for leaving belongings behind.
✅ to check before getting off
You want to check not only the dashboard, but also the seats, the trunk, and the inside of the bag.
The Consumer Affairs Agency advises people to avoid leaving their bags in the dashboard, seat, or trunk. NITE is also careful not to leave them in direct sunlight or in the car on a hot day, including in bags.
If you are not sure if the product is the target, please check the notation of "lithium ion," "lithium polymer," "Li-ion," "Li-Po" on the main unit display or instruction manual.
In-vehicle equipment such as EV, PHEV, and HV drive batteries, genuine navigation systems, and ETC are separate from the "carry-on items" this time. For in-vehicle equipment, please follow the instruction manual for each product.
⚠️ When there is an abnormality in a forgotten product
If there is an abnormal heat, swelling, deformation, or burning smell, discontinue use and charging, and consult the manufacturer or distributor.
When there is smoke or flames, please do not touch or approach and ensure your safety first. If it is difficult to deal with it yourself, do not overdo it and call 119.
🔖 and check your belongings before you get out of the car in the summer.
Source
NITE "Beware of 'summer fatigue (summer battery)'" July 15, 2026
Consumer Affairs Agency "Be careful! Lithium-ion batteries in hot weather" May 15, 2026
Consumer Affairs Agency "Don't leave smartphones and mobile batteries" July 2, 2026
JAF "Midsummer cabin temperature (user test)" August 22 and 23, 2012
The Summer Car # mobile _ battery Lithium ion battery Living with a car Creator Growth Lab
夏の暑い日、車内の温度が非常に高くなることはよく知られていますが、特にリチウムイオン電池搭載のスマホやモバイルバッテリーを車内に放置することの危険性については意外と見落とされがちです。実際、NITEから報告された自動車内でのリチウムイオン電池事故は2021年から2025年の5年間で124件に及び、そのうちモバイルバッテリーだけでも49件と高い件数となっています。これらは高温環境での放置だけではなく、使用中や充電中の事故も含んでいるためなおさら注意が必要です。 JAFの実験によると、外気温35℃の条件下でサンシェードを使っていても車内は最高50℃と非常に高温になります。ダッシュボードは79℃に達することもあり、これはスマホやリチウムイオン製品の安全性を著しく脅かす温度です。窓を少し開けても温度は45℃前後と、熱がこもりやすい環境であることがわかります。サンシェードや窓開けだけで安心せず、リチウムイオン電池搭載製品は必ず車から持ち出す習慣をつけましょう。 また、車内のチェックポイントはダッシュボードだけに限らず、シート下やトランク、バッグの中など見落としやすい場所にも注意が必要です。私自身も以前、ワイヤレスイヤホンのケースを座席の隙間に置き忘れてしまい、車から離れて気づいた時には怖くなった経験があります。それ以降は車から離れる前に必ずバッグも確認し、全部持ち出す癖をつけました。 もしも、持ち忘れた製品に異常（熱を持つ、膨らみ、変形、焦げ臭いなど）を感じたらすぐに使用をやめ、充電もしないことが肝心です。煙や炎が出ている場合は絶対に触らず、遠くに避難してから119番通報してください。このような万が一に備え、車内での安全管理意識を高めることが夏の車中泊やドライブの快適さと安全につながります。 以上のポイントを踏まえ、夏の車内に置き忘れやすいリチウムイオン電池搭載製品は全て持ち出す習慣を徹底し、快適で安全なカーライフを送りましょう。