INIU B5 20000mAh Power Bank review
By Tom Calder
Key specs
The maker's figures.
- Capacity
- 20,000 mAh
- Max output
- 22.5 W
- Ports
- 1x USB-C (in/out), 2x USB-A
A genuinely good-value 20,000mAh pack that delivers close to its rated capacity, with a clear battery display, USB-C in and out plus two USB-A outputs, and an unusually long three-year warranty. For most households wanting a reliable backup for phones and tablets, it is hard to beat at the price.
- Best for
- Keeping phones and tablets topped up during a power cut or a long day away from the mains.
- Skip it if
- You need to fast-charge or run a laptop, or want the quickest possible recharge
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Researched, not used. We haven't used this product. This review is built from the maker's specifications, owner reports and our own sizing.
What we like
- Delivers most of its rated capacity: techtest.org's tests of the BI-B5 measured 81% to 91% on the original model and 94% to 102% on the 2024 version, depending on the load (their figures, not our measurement)
- Three outputs (USB-C in and out, plus two USB-A) and a readable charge-level display
- Three-year warranty is well above the norm at this price
Worth knowing
- 22.5W output is modest — fine for phones and tablets but slow to recharge the bank itself and not enough for most laptops
- At 365g (INIU's figure) it is a chunky thing to carry every day
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Our review
INIU's B5 (model BI-B5) is a 20,000mAh, 74Wh power bank with one USB-C port and two USB-A ports, a charge display and a three-year warranty. Independent German lab testing found it gave back most of its rated capacity. It is a phone and tablet bank: the 20W USB-C port is not built for laptops.
What it is
INIU's manual gives 20,000mAh and 74Wh, a body of 134 by 71 by 25mm and 365g. The USB-C port works both ways: in, it accepts 5V 3A or 9V 2.22A, about 20W; out, it supplies 5V 3A, 9V 2.22A or 12V 1.5A, again about 20W, with USB Power Delivery and PPS. The two USB-A ports reach 22.5W (4.5V 5A) with Quick Charge and SCP. That 22.5W is the figure on most listings, but a modern phone on USB-C will charge at up to 20W. There is an LED charge display and a small built-in light.
What Techtest.org measured
Techtest.org, a German site that measures power banks on a load tester, recorded a best case of 18,248mAh from the original BI-B5, about 91% of the rating, and 16,273mAh at 9V 2A. Losses of that size are normal, because the cells are rated at 3.7V and are stepped up to 5V or more on the way out. Its phones charged at between 18.3W and 19.6W. The reviewer called it a very good everyday power bank and said it was not, or only barely, suitable for notebooks. Check that the model code on the bank is BI-B5, since the test was of that version.
Living with it
Refilling it takes about six hours from an 18W USB-C charger, ten hours from a 5V 2A charger and twenty from a 5V 1A one, by INIU's manual, so charge it before you need it. Fast charging switches off when several devices are plugged in at once. INIU asks you to use and recharge it at least once every six months and gives an operating range of 14 to 113°F, about -10 to 45°C. Electrical Safety First's advice is to unplug a power bank once charged, not to charge it overnight or while out, and to stop using one that swells or cracks; our lithium battery guide covers the rest. At 74Wh it is under the 100Wh limit the Civil Aviation Authority sets for power banks in cabin bags, and power banks must not go in the hold.
How it compares
On our power bank comparison the Anker Nano 10,000mAh is half the capacity and much lighter, with a built-in cable and 30W. INIU's own Carry 20,000mAh doubles the output to 45W with a built-in USB-C cable, which suits a small laptop or a tablet better. The Belkin BoostCharge 20K matches the capacity at a slower 15W. The B5's case is the long warranty and a reliable capacity for phones.
Our verdict
Buy it if you want a dependable bank that will recharge two or three phones through a long power cut, which is the job the government's Be Ready checklist gives a charged power bank. Skip it if you need to run a laptop, or carry it daily and mind the 365g. Either way, put a reminder in your diary to top it up every few months.
A researched review, built from the maker's specs, manual and UK listings; facts checked 2 Nov 2026. Sources: INIU BI-B5 user manual (hosted by ManualsLib); Techtest.org: INIU BI-B5 power bank test (German); Civil Aviation Authority: rules on carrying lithium batteries and power banks; Electrical Safety First: power bank safety; UK Government Be Ready: emergency kit checklist.
Who shouldn't buy this
You need to fast-charge or run a laptop, or want the quickest possible recharge — step up to INIU's 65W model (the B62) instead. If you only ever top up a single phone, a lighter 10,000mAh bank will cost less and weigh half as much.
This is a Researched review: we haven't used this product. We check every specification against at least two independent sources, re-check the UK price on a schedule where we can track it automatically, and say plainly who it isn't for. Commissions never change a rating.
If this isn’t the one
Best for Keeping a household's phones and a tablet topped up through a power cut, in a bank small enough to carry every day.
Best for Keeping phones and a USB-C laptop going through a long power cut, with no cable to forget.
as of 2 Nov 2026, 13:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.
Best for Keeping a laptop as well as phones going through a long outage or a few days away from a socket.
as of 2 Nov 2026, 13:07 GMT · Details
Product prices and availability are accurate as of the date/time indicated and are subject to change. Any price and availability information displayed on Amazon.co.uk at the time of purchase will apply to the purchase of this product.Questions
How much of its 20,000mAh does the INIU B5 actually deliver?
Techtest.org measured up to 18,248mAh from the original BI-B5, about 91%, and 16,273mAh at a heavier 9V 2A load. Some loss is normal in every power bank.
How long does the INIU B5 take to recharge?
About six hours from an 18W USB-C charger, ten hours from 5V 2A and twenty hours from 5V 1A, according to INIU's manual.
Can I take the INIU B5 on a plane?
At 74Wh it is under the Civil Aviation Authority's 100Wh limit for power banks without airline approval. It must go in hand luggage, not the hold, and must not be recharged on board.
Will the INIU B5 charge a laptop?
Only small, low-power ones, if at all. Its USB-C port gives about 20W, and Techtest.org judged it unsuitable, or only barely suitable, for notebooks.
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