A 20,000mAh power bank for ৳450 is not a bargain, it is a physics problem. No factory can fit 20,000mAh of real lithium cells into a casing that cheap, so what you are actually holding is usually a 4,000 to 6,000mAh cell wrapped in a lie. Spotting a fake power bank in Bangladesh mostly comes down to four checks you can do in under two minutes: the maths on the label, the weight in your hand, the ports on the body, and the packaging around it.
Most fakes are not clever. They are cheap, and cheap leaves fingerprints.
Why are fake power banks so common in Bangladesh?
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Because the real cost of a battery is not in the plastic shell. It is in the cells inside it, and those cells are the easiest thing to swap out without you noticing.
A genuine 10,000mAh power bank needs several 18650 or lithium-polymer cells, a proper charging circuit, and protection against overcharge and short circuit. That combination has a floor price. When you see a power bank selling for less than a branded 5,000mAh unit, the seller has cut something, and the only things left to cut are the cells and the safety board.
You will see these mostly in three places: footpath stalls in Dhaka, small electronics shops in places like Gulistan and Elephant Road, and Facebook page sellers who post a glossy photo, take bKash, and disappear. Online marketplaces are a mixed bag. Some sellers are honest, some are reselling the same fake with a better product photo.
The giveaway is usually consistency. A real brand keeps its specs, packaging, and pricing roughly stable across sellers. A fake changes its story depending on who is asking.
How do you check if the mAh rating is real?
Do the maths on the box before you do anything else.
A power bank's rated capacity is measured at 3.7 volts, the voltage of the cell. Your phone charges at 5 volts or higher. Converting between the two loses energy, so a 10,000mAh power bank realistically delivers somewhere around 6,000 to 6,500mAh to your phone after conversion and heat loss. That is normal. What is not normal is a 20,000mAh bank that charges your 4,500mAh phone once and dies.
Here is the rough test you can run in the shop:
- A 5,000mAh power bank should give a typical Android phone one full charge, maybe a little more.
- A 10,000mAh bank should give two to two and a half full charges.
- A 20,000mAh bank should give four to five full charges, and it should take most of a night to charge back up.
If a 20,000mAh bank charges your phone once and shows 20 percent left, the label is fiction. If it recharges itself from empty in 90 minutes on a normal charger, that is another red flag. Big capacity takes time to fill.
One more thing worth knowing: a real 20,000mAh power bank weighs roughly 400 to 450 grams. If the one in your hand feels like a phone, it is not carrying 20,000mAh. It is carrying plastic and air.
What does the weight and build tell you?
Weight is the single fastest check you can do, and it needs no tools.
Pick up the power bank. A genuine high-capacity unit has a heft that surprises you the first time. Cells are dense. A fake is light because there is less battery inside, and often a metal plate or two added purely to fake the weight. That trick exists, so weight alone is not proof, but a suspiciously light 20,000mAh bank is almost always fake.
Then look at the seams. Run your thumb along the join between the top and bottom casing. On a good unit the seam is tight and even. On a fake it is often uneven, with a visible gap or a sharp edge where the mold did not close properly. Press the casing gently. If it flexes or creaks, the plastic is thin.
Shake it. A faint rattle means something inside is loose, and loose cells inside a lithium battery are a safety issue, not just a quality one. You do not want a cheap unprotected cell rattling around in your bag next to your keys.
Which ports and buttons give a fake away?
Ports are where fakes get lazy, because adding real components costs money.
Genuine power banks usually have clearly labelled ports: one or two USB-A outputs, one USB-C that may handle both input and output, sometimes a micro-USB for charging. The labels are printed or molded, not stickers. On fakes you will often see:
- A USB-C port that is physically there but only charges the bank, not your phone, or does nothing at all.
- Ports that are slightly misaligned with the casing, sitting crooked or recessed.
- Sticker labels over the ports that peel at the corner within a week.
- A four-light indicator where all four lights turn on the moment you press the button, regardless of charge level.
That last one is a classic. On a real power bank the lights step up as it charges. On a fake, the indicator is often decorative, wired to light up all at once so it looks full.
Test it in the shop if you can. Bring your own cable and your own phone. Ask the seller to let you plug in for two minutes. A real power bank will show a charging icon on your phone immediately and the percentage will climb. A fake may show the icon and then barely move, or the phone may report "charging slowly" on a bank that claims fast charge.
What packaging red flags should you look for?
Packaging is where the story falls apart fastest, if you read it.
First, check the brand name against the logo. Fakes lean on near-misses: an extra letter, a swapped character, a font that is almost but not quite right. If the name feels slightly off, search it on your phone before you pay. If nothing comes up except the same product photo on a dozen Facebook pages, that tells you something.
Second, read the specifications panel. A real product lists input voltage, output voltage, capacity, and often a model number. A fake tends to list capacity in giant letters and nothing else. If the box says 30,000mAh and the power bank itself says 20,000mAh, walk away. That mismatch is not a printing error.
Third, look at the print quality. Genuine packaging has sharp text and consistent colour. Fakes have blurry logos, spelling mistakes, and grammar that reads like it was translated twice. "High capacity long lasting power bank for all mobile phone" on the box is not a good sign.
Fourth, check for a hologram, serial number, or scratch code. Not every real brand uses them, but most reputable ones do. If the box has a scratch panel and the code underneath does not verify on the brand's website, you have your answer.
Should you buy a power bank online or in person?
Both work, but the checks are different.
| Where you buy | What you can check | What you cannot check |
|---|---|---|
| Footpath or local market | Weight, build, ports, packaging, live charging test | Whether the seller will still be there next week |
| Facebook page seller | Photos, reviews, price | Almost nothing physical, and returns are often impossible |
| Online marketplace | Listing specs, seller rating, return policy | Whether the unit matches the photo until it arrives |
| Brand showroom or authorised shop | Everything, plus warranty | Price is usually higher |
In person, you have the advantage of holding it. Use that. Ask to plug your phone in. Any honest seller will say yes. A seller who refuses, or who rushes you, is telling you what you need to know.
Online, the leverage is different. Read the negative reviews first, not the positive ones. Look for comments about how many charges people actually got, not how fast it shipped. If a listing has dozens of five-star reviews all posted within the same week with similar wording, that is a pattern worth noticing. And check the return policy before you pay, because a fake that arrives in the mail is much harder to argue about than one you rejected in person.
One practical tip for cash on delivery: open the parcel in front of the delivery person before you hand over the money, if the seller allows it. Weigh it in your hand, check the ports, look at the packaging. Once you have paid, your options shrink considerably.
What should you actually do before paying?
Set a price floor in your head and stick to it. If a power bank is priced far below everything else with the same claimed capacity, the capacity is the thing that has been cut. There is no secret supplier selling real 20,000mAh units at a third of the market price.
Then run the four checks in order. Do the mAh maths against your phone's battery size. Weigh it in your hand. Look at the seams and the ports. Read the packaging properly, including the small print. Any single red flag is worth pausing on. Two red flags means walk away, even if the price is tempting, because a power bank that fails is not just wasted money. It is a lithium cell of unknown quality sitting in your bag, and that is a different kind of problem entirely.
Buy from a seller you can go back to. In Bangladesh that matters more than a ৳200 saving.