This is the English edition of a review from my Japanese YouTube channel, iestaLife. I review gadgets from my home studio in Japan, so product links go to Amazon Japan.
Quick take
The KEEZING “ultra-thin” MagSafe power bank is listed on Amazon Japan as 0.08 cm thick with 8,000 mAh. The thickness is clearly a typo (it measures about 9 mm), and in my test the capacity did not live up to the rating in my test either: it charged my iPhone 17 Pro Max from 18% to only 69%, about the same as a 5,000 mAh battery I have used for a year. I stopped using it.
What I tested
- KEEZING ultra-thin MagSafe power bank, listed as 8,000 mAh (¥2,998 on Amazon Japan when I bought it)
- A slim 5,000 mAh MagSafe power bank I have used for about a year
- iPhone 17 Pro Max with the case removed, charged by MagSafe from 18% and left untouched until the power bank ran out
What I found
| Rated capacity | iPhone 17 Pro Max charge | Time until empty | |
|---|---|---|---|
| KEEZING ultra-thin | 8,000 mAh | 18% → 69% | about 1.5 hours |
| My slim power bank | 5,000 mAh | 18% → just over 70% | just under 2 hours |
The iPhone 17 Pro Max has a battery of a little over 5,000 mAh. Rated capacity and the charge a phone actually receives cannot be compared directly, but I expected the “8,000 mAh” unit to at least beat the 5,000 mAh one. It did not. I did not open it up, so I cannot say whether the cells are smaller than claimed or the wireless efficiency is very poor; I can only say it delivered far less than the rating led me to expect.
Heat. Both power banks got noticeably hot (by touch; I did not measure temperature). After about an hour the iPhone showed “slow charging”. Not too hot to touch while idle, but uncomfortable if you hold the phone and use it while charging. My older 5,000 mAh battery has also started making a faint ticking noise over the past few months.
Size and weight. The KEEZING is about the same footprint as my 5,000 mAh battery, slightly shorter, and weighs about 108 g. It looks well finished. But a listing that gets the unit wrong by a factor of ten made me question how carefully the rest was checked.
Who it’s for
I do not recommend it. If you want a slim MagSafe battery, choose an established brand and treat any thin battery that claims a big jump in capacity at the same size with suspicion. Read the low-star reviews too; complaints about heat and low capacity were there for this one.
Watch the review
The video is in Japanese. Useful points: around 03:40 the KEEZING result, 09:00 the 5,000 mAh result, 11:10 my conclusion about thin batteries. The earlier unboxing video (also in Japanese) is here.
Limitations
This was a single run per battery, measured by the iPhone’s own battery percentage over MagSafe, not a lab capacity test. The price is what Amazon Japan showed at the time of recording.
Products
I am not linking the KEEZING power bank because I do not recommend it. In the video description I suggested this Anker model as a safer choice; I did not test it in this video.
Anker Nano Power Bank (5,000 mAh, MagGo, Slim): on Amazon Japan
The Amazon Japan link above is an affiliate link. As an Amazon Associate, I earn from qualifying purchases. Check the listing for the exact model, current price and shipping availability in your region.
More reviews in English
All Chargers & Cables (29) →Browse all English reviews →
This review is also available in Japanese.