Most Power Banks Are Overhyped — Here's What to Buy

That one time your power bank betrayed you

You know the drill. You're at a wedding, phone on 8%, power bank in your bag — the one you bought because it said 20000mAh on the box. You plug in. It trickle-charges for 20 minutes and then dies. Your phone went from 8% to 14%. Thanks for nothing.

This happens constantly in India, and it's almost never bad luck. It's about buying the wrong spec.

The mAh number is a trap

Honestly, mAh is the first thing everyone looks at — and it's also the most misleading. A 20000mAh power bank does not give your phone 20000mAh. Not even close.

Here's why: conversion efficiency. Power banks lose 30–40% of stored energy converting from their internal battery voltage to your phone's charging voltage. Add cable losses and heat — you're getting roughly 60–65% efficiency on a good day.

Real-world output ≈ mAh × 0.6

That "20000mAh" bank? You're getting around 12000–13000mAh out of it. Still decent, but not the four full phone charges the box implies.

What to actually check:

• Watt-hours (Wh) — the honest number, printed on some boxes
• Actual charges at your phone's specific battery size
• Avoid inflated numbers from brands with zero reviews

Speed matters more than size for daily use

Here's the thing — if you're using a power bank every day, how fast it charges your phone matters more than how big it is. A 10000mAh bank with 22.5W fast charging beats a 20000mAh brick pushing 10W on any Monday morning rush.

Look for these output speeds:

• 18W — minimum for fast charging most iPhones and Androids
• 22.5W or 25W — ideal for mid-range and flagship phones in India
• 65W PD — if you also want to charge a laptop

Also check input speed — how fast the bank itself recharges. A 20000mAh bank with 10W input takes 10+ hours to fill up. One with 22.5W input? Around 4–5 hours. That's the difference between overnight charging and plugging in after dinner.

The ports situation

Most Indian buyers need at least two output ports. One for the phone, one for earbuds or a second device.

No cap — USB-C is the port to prioritize now. If a power bank only has Micro-USB input in 2025, skip it. USB-C charges faster, the cable is reversible, and you already own one.

A USB-A port is still worth having for older accessories. But USB-C in and USB-C out is the setup to aim for.

Build quality signals to watch for

You can't always tell from specs, but some patterns are consistent:

• Weight — a real 20000mAh lithium cell weighs 350–400g. Suspiciously light means the capacity is likely exaggerated
• BIS certification — mandatory for power banks sold in India; if it's not listed, it hasn't passed safety standards
• Brand track record — Ambrane, Syska, Redmi, OnePlus, and Anker all have real reviews and service in India; unknown names are a gamble

What I'd actually buy

For most people, a 10000mAh power bank with 22.5W fast charging and USB-C in/out is the sweet spot. Light enough to carry every day, fast enough to top off your phone in under an hour, and honestly — most people don't need more than two charges to get through a trip.

If you travel frequently or own a laptop, step up to 20000mAh with 65W PD. It covers your phone and your ultrabook without carrying a separate adapter.

If you want options already filtered for Indian buyers, take a look at our collection.

Written By Aman Kumar, tech specialist at Styleus