Power Banks Review
Xiaomi Power Bank 4i 20000mAh 33W Review: Big, Cheap, Heavy
Our verdict
The Xiaomi Power Bank 4i 20000mAh 33W gives about three phone charges and three outputs for a low price, but it weighs 440 g and takes around 7 hours to refill.
Buy it if
- Families sharing one bank across two or three phones during power cuts
- Train and bus journeys where weight matters less than capacity
- Buyers who want a known brand with Xiaomi's service reach
Skip it if
- You want something to carry in a trouser pocket
- You need to charge a laptop at full speed
What we like
- Three outputs: one USB-C and two USB-A
- USB-C rated up to 33 W out and 30 W in
- Low-current mode for earbuds and smartwatches
- Sold widely online and in Xiaomi stores
What we don’t
- 440 g is heavy for daily carry
- About 6.9 hours to recharge even on an 18 W charger, per Xiaomi
- Fast charging drops when two ports are used together
- No charger in the box
Score breakdown
- Performance
- 7.2
- Build quality
- 7.4
- Design
- 6.0
- Features
- 7.6
- Value for money
- 8.8
- After-sales service
- 7.8
The Xiaomi Power Bank 4i 20000mAh is for people who want the most charge for the least money and don’t mind carrying it in a bag. You get three outputs and a 33 W USB-C rating at a launch price far below most 20,000 mAh banks. The cost is weight: at 440 g it is a bag item, and it takes most of a night to refill.
How many phone charges will I really get?
Xiaomi estimates about 3.3 charges of an iPhone 15 Pro Max and 3.4 of a Xiaomi 13 Pro. Those figures already allow for conversion losses, which is more honest than quoting 20,000 mAh alone. We could not find an independent lab test of usable capacity for this model, so we can’t confirm Xiaomi’s numbers. Anker’s similar Zolo 20K delivered 80–92% of its rating in techtest.org’s tests, and that is a reasonable range to expect from any well-made bank.
Does it actually charge at 33 W?
Only on the USB-C port, and only with one device plugged in. Per the published spec, plugging in a second device drops all ports to a shared 5 V / 3 A, which means slow charging for both. Several owner reviews say their phones charge closer to 18–25 W. That is still fast for most Android phones and iPhones, which accept around 20–27 W anyway. Don’t buy it to run a laptop at full speed.
How long does it take to recharge during power cuts?
This is the weak spot. Xiaomi quotes about 6.9 hours on an 18 W charger and 10.5 hours on a 10 W one, and owners report 6–7 hours in practice. If your area has scheduled cuts, top it up overnight rather than expecting a quick refill when power returns. The input is rated up to 30 W, but Xiaomi does not publish a time for a 30 W charger, and no charger comes in the box.
Is it too heavy to carry every day?
At 440 g and about 15 × 7 × 2.6 cm, it is closer to a small book than a pocket gadget. Owners often call it heavy and some say the finish is slippery. For a laptop bag or a long train journey it is fine. For daily pocket carry, a 10,000 mAh bank makes more sense.
Can I take it on a flight?
Yes, in hand baggage. A 20,000 mAh cell at the usual 3.6–3.7 V comes to roughly 72–74 Wh, under the 100 Wh limit. Under the DGCA’s 2026 advisory, you can’t use a power bank to charge devices during the flight, and it should stay with you rather than in the overhead bin.
Is Xiaomi’s service and BIS compliance reliable?
Xiaomi sells the 4i on its own site, on Amazon.in and Flipkart, and in Mi stores, so getting a defective unit replaced is easier than with smaller brands. Power banks sold in India must be registered with BIS, so check the R-number on the box against the BIS website before you buy from a third-party seller.
How we researched
We have not used the Xiaomi Power Bank 4i. This review draws on Xiaomi India's spec page, launch coverage from Notebookcheck and FoneArena, retailer listings on Croma and Reliance Digital, and owner reviews on Amazon.in and other marketplaces.
We have not tested this product ourselves. This review is based on published specifications, the manual, other publications’ tests and owner feedback.
How does the Xiaomi Power Bank 4i 20000mAh 33W Sonic Charge compare?
-
Anker Zolo Power Bank (20K, 30W, Built-In USB-C Cable) B− 7.0
Anker's Zolo 20K has a built-in USB-C cable, is lighter (318 g per Anker, 356 g per techtest.org) and showed 80–92% usable capacity in a German lab test. The Xiaomi costs less and has an extra USB-A port, but no independent capacity test we could find.
-
Ambrane Stylo 20K 20000mAh Power Bank (PP-205) C 6.1
Both are 20,000 mAh banks with three outputs. The Xiaomi is rated for 33 W against the Ambrane's 20 W and has a larger service network; the Ambrane is lighter on paper but carries only a 180-day warranty.
Which variant should you buy?
| Jet Black / Nitro Green / Turbo Blue | Colour only; capacity, ports and output are the same. |
|---|
Key specs
| Rated capacity | 20,000 mAh |
|---|---|
| Ports | 1 × USB-C (in/out), 2 × USB-A (out) |
| USB-C output | Up to 33 W (20 V / 1.5 A) |
| USB-A output | Up to 12 V / 1.67 A |
| Dual-port output | 5 V / 3 A shared |
| Input | USB-C, up to 30 W |
| Recharge time (Xiaomi) | About 6.9 h (18 W), 10.5 h (10 W) |
| Weight | 440 g |
| Dimensions | 150.6 × 72.2 × 26.3 mm |
Questions buyers ask
How many times can the Xiaomi Power Bank 4i 20000mAh charge a phone?
Xiaomi estimates the Power Bank 4i 20000mAh gives about 3.3 full charges of an iPhone 15 Pro Max and 3.4 of a Xiaomi 13 Pro. Real numbers depend on the phone's battery size and conversion losses.
Does the Xiaomi Power Bank 4i really charge at 33 W?
The Xiaomi Power Bank 4i is rated for 33 W only on its USB-C port, and only when one device is connected. Several owners report lower speeds in practice, often closer to 18–25 W depending on the phone.
Can I take the Xiaomi Power Bank 4i 20000mAh on a flight in India?
Yes, in cabin baggage only. A 20,000 mAh cell works out to roughly 72–74 Wh, under the 100 Wh limit, but DGCA rules bar using power banks to charge devices during a flight and they should not go in overhead bins.
How long does the Xiaomi Power Bank 4i take to recharge?
Xiaomi says the Power Bank 4i 20000mAh takes about 6.9 hours with an 18 W charger and about 10.5 hours with a 10 W charger. No charger is included in the box.
Also consider
- Anker
Power Banks
Anker Zolo 20K 30W (A1689) Review: Handy Cable, Recall History
The Anker Zolo 20K 30W (A1689) is a practical cable-included power bank that delivered 80–92% of its rated capacity in lab tests, but it throttles under sustained 30 W loads and early units were recalled.
- Ambrane
Power Banks
Ambrane Stylo 20K Review: Cheap 20,000 mAh, Short Warranty
The Ambrane Stylo 20K is an inexpensive 20,000 mAh bank with three outputs and 20 W charging, but its 180-day warranty, slow 8-hour refill and lack of independent capacity tests hold it back.