What the advertised 5000 mAh is really worth
On the spec sheet, the Anker Nano A1665 lists 5000 mAh, around 18.5 Wh under the usual power-bank voltage assumption (3.7 V). The cell actually fitted inside, a LiPo unit from LS, in fact runs at a nominal 3.87 V, which puts the pack's real energy at around 19.4 Wh, a slightly more favorable figure than the printed one. A gap of this size is common on this type of product: the advertised mAh figure remains a conversion, never a direct measurement of available energy.
In practice, this capacity translates into a single smartphone charge in the large majority of cases, and a full charge only on the least power-hungry models. On a large Pro or Pro Max model, the available figures range from 77 to 95% of a charge before the power bank runs out, never 100% in one cycle. That is not a hidden flaw: Anker has never promised more than one charge, and the product's extremely thin format mechanically forces this capacity ceiling. The real point worth keeping in mind lies elsewhere: at an equal budget, a thicker competitor of the same rated capacity generally delivers a fuller charge, precisely because it has not sacrificed as much internal volume to thinness.
15 W over Qi2: a ceiling, not a guaranteed rate
The figure most prominent on the box is 15 W wireless charging, twice the speed of a standard Qi charge capped at 7.5 W. The built-in charging circuit (a CVS controller identified by its part number during a teardown) actually manages three distinct tiers: 5 W in basic Qi mode, 7.5 W in classic MagSafe mode for compatibility with older accessories, and 15 W only in full-power Qi2 mode. That last tier assumes near-perfect alignment, generally achieved on a bare phone or with a very thin case, which is why the real-world result varies noticeably from one use to another.
Another figure worth treating with caution: the flagship marketing claim, presented as "25% charge in X minutes" on a recent iPhone, exists in at least three different versions depending on which manufacturer page is consulted, with gaps of several minutes for the same promise. None of these figures comes with a detailed measurement protocol, and no independent measurement available settles between them with precision. The most solid figure remains the overall result already mentioned: an iPhone 16 Pro charge brought to a little over three quarters before the power bank runs out, a result slightly behind the best direct competitor measured under the same conditions.
Heat, the most persistent friction point
An infrared thermometer reading shows around 38 °C at the housing's hottest point during wireless charging, under the 40 °C threshold stated by Anker. That figure sits alongside a noticeably less flattering picture elsewhere: warmth runs distinctly higher, particularly on the thinnest iPhone models such as the iPhone Air, to the point of limiting use to a single occasional charge rather than a comfortable full one. On the UK marketplace, heat comes up as a theme in more than sixty product reviews, making it the most cited friction point on this product.
Anker itself devotes a question in its official FAQ to "why does my phone get warm while charging," a sign the phenomenon is frequent enough to be anticipated rather than accidental. The housing nonetheless includes a graphene sheet and two separate temperature sensors, one on the cell side and one on the wireless charging coil side, identified during a teardown. This warmth therefore looks less like a fault than a consequence of the physics of fast magnetic charging inside a very thin housing: less thickness means less material to dissipate heat, a trade-off the product's record-setting format makes hard to avoid entirely.
8.6 mm: the product's real strength
This is the one area where the Anker Nano A1665 carries no serious reservation. At 8.6 mm thick and 122 g, it ranks among the thinnest MagSafe power banks available, noticeably below the segment's usual references: the Ugreen Nexode Mini 5000 mAh measures 13.1 mm for 145 g, and the range's own larger sibling, the Anker MagGo 10K, reaches 19.8 mm for 250 g. Once attached to the back of an iPhone, the Nano A1665 adds barely more thickness than a standard protective case, a claim neither of the two competitors mentioned can make.
| Criterion | Anker Nano A1665 | Ugreen Nexode Mini 5000 mAh | Anker MagGo 10K |
|---|---|---|---|
| Capacity | 5000 mAh | 5000 mAh | 10,000 mAh |
| Thickness | 8.6 mm | 13.1 mm | 19.8 mm |
| Weight | 122 g | 145 g | 250 g |
| Wireless charging | Qi2 15 W | 7.5 W | Qi2 15 W |
| USB-C | 20 W | 60 W (cable included) | 27 W |
Magnetic grip in use validates this design choice: on a bare phone, alignment holds with no slipping or perceptible play, including under forced use. This format is not free, though: it directly explains both the capacity limited to 5000 mAh (less internal volume available for the cell) and the sensitivity to heat covered above (less material to dissipate warmth). Thinness and battery life pull structurally in opposite directions on this product format, and Anker has clearly sided with the former.
A specified limit: thick, non-magnetic cases
Anker officially advises against using the Nano A1665 with a non-magnetic case thicker than 2.5 mm: beyond that, magnetic alignment degrades and charging speed suffers directly. A thick, reinforced-style protective case noticeably degrades magnetic alignment and charging speed, which favors either a thin magnetic case or using the phone bare. This is a real constraint to plan for before buying, particularly for anyone who already owns a sturdy protective case that is not MagSafe-compatible: it means either switching cases or accepting degraded alignment and charging.
Against the MagGo 10K: the same trade-off, at a larger scale
The Nano A1665 shares its Qi2 15 W charging technology with the MagGo 10K, the higher-tier model in the same Anker range, already reviewed on this site. The MagGo doubles the rated capacity (10,000 mAh) but gives up thinness entirely: 19.8 mm and 250 g, more than double the Nano A1665 on both measurements. Its wireless output at full power caps at a little over three quarters of the stated energy, a gap of the same kind as the one affecting the Nano A1665 with the iPhone 16 Pro. This point therefore applies to the whole range, not just this one model: Qi2 magnetic charging appears to fall structurally short of its rated value whenever charging power is at its maximum, a pattern tied to the technology itself rather than to one particular product.
The choice between the two comes down to a question of format rather than technological reliability: the Nano A1665 for discretion and everyday carry, the MagGo 10K for battery life and a fuller status display, at the cost of noticeably greater bulk and weight.
Build, wear, and after-sales support
The Nano A1665's metal frame gives a solid first impression in hand, a consistent point across the material available. Over extended use, several cosmetic wear marks do show up: a logo that fades after several weeks of daily use, a paint chip on the edge after being carried while loaded, without these marks affecting how the product functions. A display fault found on the charge indicator of one unit was resolved through a straightforward replacement from Anker's after-sales support, a positive sign of support responsiveness when a real problem occurs.
Who is the Anker Nano A1665 for?
This format suits first and foremost anyone looking for a daily top-up charge without adding pocket bulk: a commute, an evening out, a day of travel where the iPhone's battery dips by late afternoon. The promise it keeps is clear, one smartphone charge in a format that nearly disappears once clipped to the phone. For anyone needing to cover several days without a recharge, or who already owns a thick non-magnetic case, a bulkier power bank such as the MagGo 10K or an equivalent competitor remains the better fit: the Nano A1665's record thinness is paid for directly in battery life and tolerance for sturdy protective cases.
