上周一個朋友跟我抱怨，說新買的無線充電器是個廢物：手機放上去一晚上才充了六成，背面烫得能焐手。我讓他把手機壳摘了再試——第二天他來道歉了，裸機半小時充進去 20% 多，溫度也正常。元凶不是充電器，是他那個帶金属裝飾環的「輕奢皮革壳」。這種案例我這幾年見得太多了，所以干脆把公開實測資料整理一遍，聊聊手機壳這個最容易被忽略的變量。

Last week a friend complained that his new wireless charger was useless: the phone gained barely sixty percent overnight and the back was hot to the touch. I told him to take the case off and try again — the next day he apologized. Without the case, the phone charged over 20% in half an hour at normal temperature. The culprit was not the charger, but his leather case with a decorative metal ring. I have seen this so many times that I decided to put the public test data together and talk about the most overlooked variable in wireless charging: the phone case.

先說材質，這是最硬的一條線。有實验室做過對比：0.5mm 的 TPU 軟壳，充電效率只掉 5%–10%，基本無感；而 0.2mm 的金属壳，效率直接砍掉 40%–60%——注意，金属壳更薄，但更致命，因為金属會反射和吸收交變磁場，等于在發射線圈和接收線圈之間立了一堵牆。帶金属裝飾環、磁吸卡包這類「局部金属」的壳介于兩者之間，效率掉 15%–30%，而且經常出現充電時斷時續、手機反复響起連接提示音的情况。所以第一條避坑原则很簡單：純硅膠、純 TPU、純 PC 隨便用，任何帶金属件的壳都要打問號。

Material is the hardest rule. Lab comparisons show that a 0.5mm TPU case only costs you 5%–10% of charging efficiency — barely noticeable. A 0.2mm metal case, however, cuts efficiency by 40%–60%. Note that the metal case is thinner yet far more damaging, because metal reflects and absorbs the alternating magnetic field, effectively building a wall between the transmitter and receiver coils. Cases with partial metal — decorative rings, magnetic card holders — sit in between, losing 15%–30% and often causing the connection to drop and reconnect repeatedly. So rule one is simple: pure silicone, TPU or PC cases are fine; anything with metal parts deserves a question mark.

再說厚度。今年有媒體拿一款三合一無線充電器配六款不同厚度的壳做過一輪很細的實測，結論值得抄下來：0.3mm 的超薄 TPU 壳能稳定跑滿 15W，磁吸定位不到兩秒；1.2mm 的 PC 硬壳大多還能滿功率，但已經開始出現小毛病——有的降到 13.6W，有的長時間充電會有輕微嗡鳴；到了 2.8mm 以上的厚重防摔壳，全軍覆沒：有的降到 7.5W 還過熱，有的只剩 5W，還有雙層結構的壳直接讓手機鏡頭防抖報錯。1.2mm，基本就是磁吸無線充的舒適區紅線。

Then there is thickness. This year a reviewer ran a detailed test pairing one 3-in-1 wireless charging stand with six cases of different thicknesses, and the conclusions are worth writing down. A 0.3mm ultra-thin TPU case held a full 15W with magnetic alignment locking in under two seconds. At 1.2mm, hard PC cases mostly kept full power but small issues appeared — one dropped to 13.6W, another produced a faint hum during long sessions. Above 2.8mm, every rugged case failed: one fell to 7.5W and overheated, another managed only 5W, and a dual-layer case even triggered camera OIS errors. Roughly speaking, 1.2mm is the comfort-zone red line for magnetic wireless charging.

磁吸壳還有個更隐蔽的坑：吸得住不等于對得準。有博主實測過，非認證的磁吸壳雖然「啪」一聲吸上去很爽，但磁環位置差個一兩毫米，功率就能從 15W 掉到 7.5W——你還看不出任何異常，手機顯示在充電，只是慢了一倍。這也是為什麼我一直建議，用磁吸無線充或者磁吸無線充電寶的人，壳盡量認準帶 MFM 認證的，貴個幾十塊，换來的是磁環位置和磁力強度都按標準來。夾在中間省錢，最後省掉的是充電速度。

Magnetic cases hide a sneakier trap: snapping on firmly does not mean aligning accurately. Reviewers have measured that an uncertified magnetic case can feel perfectly satisfying when it clicks into place, yet a ring offset of just one or two millimeters drops power from 15W to 7.5W — with no visible symptom at all. The phone still says charging, just twice as slow. That is why I keep telling people who use magnetic chargers or magnetic power banks to stick with MFM-certified cases. The extra cost buys you a magnet ring positioned and rated to spec. Saving money in the middle layer usually means losing charging speed.

最後給一套很實用的自查方法。第一招是「摘壳對照法」：懷疑充電慢，摘壳充十分鐘、戴壳充十分鐘，各記一次電量漲幅，差距超過三分之一，壳就是主要嫌疑人。第二招看發熱：戴壳充電時背面明顯比裸機烫，說明能量在壳那一層變成了熱，長期這樣對電池壽命沒好處，尤其是整夜充電的人。第三招留意場景：現在很多家居公共場所無線充是嵌在桌板下面的，隔着桌板再隔一層厚壳，距離早就超出 Qi 協議的有效範圍，充不進是正常的，別急着投诉咖啡館。

Finally, a practical self-check routine. First, the case-off comparison: charge ten minutes with the case and ten minutes without, note the percentage gained each time — if the gap exceeds one third, the case is your prime suspect. Second, watch the heat: if the back feels clearly hotter with the case on, energy is being turned into heat inside that layer, which is bad news for battery longevity, especially for overnight chargers. Third, mind the scenario: many under-desk wireless chargers in cafes and hotels transmit through the tabletop already, and adding a thick case pushes the distance beyond the effective range of the Qi protocol — failing to charge there is physics, not a reason to complain to the barista.

順帶說一句選購視角的建議。真正靠譜的無線充電器廠商，尤其是做設計與定制、生產與銷售一體的那類，規格書裡會老老實實寫一行「兼容壳厚 ≤ 3mm」或者「建議壳厚 ≤ 1.2mm（磁吸）」。這行小字比宣传頁上的大字重要得多——它意味着廠商真的按帶壳場景做過線圈功率和溫控標定。下次挑多設備無線充或者充電底座，不妨先翻規格書找這一行，找不到的，直接下一個。

One last tip from a buyer's perspective. Serious wireless charger makers — especially those handling design, customization, manufacturing and sales in-house — will honestly print a line like "case compatibility ≤ 3mm" or "recommended case thickness ≤ 1.2mm (magnetic)" in the spec sheet. That small line matters far more than the big claims on the marketing page, because it means the coils and thermal limits were actually calibrated for real-world, case-on use. Next time you shop for a multi-device wireless charger, look for that line first. If it is missing, move on to the next product.

本文由山務原創發布，转載請注明出處。

Copyright © 2026山務 . All Rights Reserved.