Charmast 20000mAh Power Bank with Built-In Cables: Review — Worth Buying?
The Charmast 20000mAh with built-in cables is for people who always forget their charging cable at home or at the office. It charges decently — 22.5W is solid for a power bank in this class — though it doesn't sit flat in a pocket and it's on the heavier side. If your main pain point is "forgot the cable again," buy it without a second thought. If you want the thinnest, lightest everyday power bank, keep looking.
How many times have you had a fully charged power bank — and not a single cable in sight? Happens to me constantly: the cable's in another bag, in the car, or someone borrowed it "just for a minute." So there you are at the station with a dead phone and a fully charged brick that, without a cord, is just a heavy piece of plastic. Charmast apparently got the memo and built a bank where the cables can't go missing, because they're physically attached to the case.
The idea itself isn't new — plenty of brands build in cables — but this one has a pair of them sticking out plus a separate USB-C port for 22.5W fast charging. That's not a record-breaking number, but for a power bank in this size class it's a solid working speed: your phone goes from 15% to a respectable 70-80% in about an hour, provided you're charging through the bank's own cable rather than the plain USB-A output.
How it actually plays out day to day
The most common scenario isn't a hike or some far-flung trip — it's an ordinary workday when your phone hits 12% at three in the afternoon and the nearest outlet is on another floor, or there isn't one. You grab the bank, plug in the built-in cable, and keep working. No digging through your bag for a stray cord.
The second scenario where this thing genuinely earns its keep: a train or bus ride with no outlets for hours. The person next to you has a dead phone and, of course, nobody has a cable. You just hand over the bank — cable included.
There's one drawback, and it's an obvious one: if you're on a nonstandard connector — say, Lightning on an older iPhone, while the built-in cable is USB-C — all that convenience evaporates and you're back to carrying a separate cord. So before buying, check exactly which connectors are built in and whether they match your phone.
20000mAh works out to roughly 3-4 full smartphone charges, depending on the model. Real-world output is a bit lower because of voltage-conversion losses — that's true of every power bank, and Charmast isn't padding its numbers here. For a three-day work trip or a festival weekend, that's plenty, as long as you're not also topping up a tablet every night.
What else to consider
The obvious rival in this weight class is the 20000mAh power bank lineup from Anker, including a model with a built-in USB-C cable that costs a bit more but carries a reputation for rarely letting you down over the years. Anker wins on predictability and support; Charmast wins on price, and it often throws in two built-in cables instead of one.
Compared with classic banks that skip the built-in cables — the ones that are a little cheaper up front — the savings are an illusion: sooner or later you buy a cable anyway, and then you lose that one too. So the premium for the built-in cord tends to pay for itself pretty quickly if you're genuinely the kind of person who loses cables (and honestly, most of us are).
The honest verdict
Buy it if you're the person who's always cable-less at the worst possible moment, and if the bank's connectors match your devices. This solves the "forgot it at home" problem — it isn't an attempt at the thinnest, lightest accessory on the market. Nobody was optimizing for compactness here; you'll feel it in a jacket pocket, though it slides into a bag without any fuss.
Skip it if you value minimalism and don't mind carrying a separate good cable — a simpler, lighter power bank without the built-in extras will be both cheaper and easier on your jeans pocket.
For the exact number that matters — item price, forwarding, and import duty combined — check the full landed cost for your country on dede.sh rather than going by the listing price alone; it's the only figure worth comparing against Anker or the shop down the street.
FAQ
For 2-3 days of regular use, yes — as long as you're only charging a phone. Add earbuds, a smartwatch, and a tablet every evening, and plan on a day or two, not more.
If you're willing to pay a bit more for peace of mind and longevity, go Anker. If you want the same built-in-cable idea for less, and don't mind a slightly shorter charge-cycle lifespan, Charmast does the job.
Yes — 20000mAh falls within standard airline limits (usually up to 100Wh), just keep it in your carry-on rather than checked luggage.
Not directly — charging speed is capped by the slowest link in the chain, which is your phone. But it doesn't hurt to have the headroom if you upgrade to a faster device later.
Still torn between models? Check out what else is available in the portable chargers category — there are lighter options and more powerful ones too.