Most INIU power banks refill in about 2–6 hours, depending on capacity, USB-C PD input, and the wall charger you use.
If you’re sizing up an INIU portable charger and want a straight answer on refill time, the short version is this: smaller 10,000mAh units often finish in a couple of hours with a fast USB-C Power Delivery (PD) charger, while larger 20,000mAh packs usually wrap up in 4–6 hours with a matching PD source. The exact number depends on input wattage, cable quality, and whether you leave a phone plugged in during the top-up.
INIU Power Bank Charging Time — What Affects It
Charging time is driven by three variables: battery capacity (mAh), supported input speed (the PD rating on the bank), and the wattage of your wall charger. A 10,000mAh bank paired with an 18–30W PD charger can be done in a few hours. Double the capacity to 20,000mAh and you roughly double the time at the same input speed. If your charger is slower than the bank’s input rating, the wall adapter becomes the bottleneck.
Capacity Classes, Inputs, And Typical Refill Windows
INIU sells multiple lines, from slim 10K models (B41/B61/B6 families) to 20K workhorses (B5/B62) and a 27K option (B64). Exact input specs vary by unit, but the refill pattern is predictable across capacity classes when you pair the bank with a PD charger that meets or beats its rated input.
| Capacity Class | Recommended PD Input | Typical Full Recharge |
|---|---|---|
| 10,000mAh (B41/B61/B6 class) | 18–30W USB-C PD | ~2–3 hours |
| 20,000mAh (B5/B62 class) | 20–45W USB-C PD | ~4–6 hours |
| 27,000mAh (B64 class) | 30–65W USB-C PD | ~5–7 hours |
These windows assume a quality USB-C PD cable, a wall adapter plugged directly into a mains outlet, and no phone or tablet drawing power while the bank refills. If you use a 10W or older 5V/2A brick, expect times to stretch by two to three times. If the bank supports PD input and you feed it with the right adapter, hours drop sharply.
Quick Math: How The Hours Are Estimated
Two numbers shape the math: stored energy and input power. A 10,000mAh pack holds about 37Wh (10Ah × 3.7V nominal cell voltage). A 20,000mAh pack holds about 74Wh. Divide stored energy by the effective charging power to get a ballpark time. Real systems lose some energy as heat and conversion, so we use an efficiency range of 80–90% for practical estimates.
Example Walkthrough
Take a 20,000mAh bank. That’s ~74Wh. With a 20W PD charger and ~85% end-to-end efficiency, usable charging power lands near 17W. 74Wh ÷ 17W ≈ 4.4 hours. Add taper at the top and brief overhead, and you land near 5–6 hours with a proper PD adapter. Feed that same pack with a 10W brick and the estimate jumps near 8–10 hours.
Model Lines And What To Expect
INIU’s lineup changes, yet the behavior stays predictable when you match capacity with PD input. The slim 10K models (like B41, B61, and B6) accept USB-C input and finish fast with 18–30W PD. The 20K class (B5 and B62) holds roughly double the energy, so it needs double the time at the same wattage or a beefier PD brick to keep hours in check. The 27K B64 adds a bigger reservoir and a bright display, so pairing it with a 45–65W PD adapter helps keep the wait reasonable.
What The Manufacturer Hints Tell You
INIU’s product pages and guides call out fast USB-C in/out on many models, PD 3.0 compatibility, and mid-range to high PD wattage. You’ll see claims like “charge an iPhone to around 60–65% in 25–30 minutes” for output, which implies strong input circuitry as well. INIU’s own guidance frames a 10K bank at roughly 2–3 hours with an 18–30W PD adapter and a 20K bank around 4–6 hours when fed properly—numbers that match the math and field tests with like-for-like competitors.
Pick The Right Charger To Hit The Fast Window
The bank can only drink as fast as the adapter and cable allow. A matching or slightly higher PD wattage than the bank’s input spec is ideal. If the bank tops out near 20–30W on input, a 30W certified USB-C PD adapter is a safe bet. For higher-end units that accept more, a 45–65W adapter saves time, especially on 20K–27K packs.
USB-C PD: The Standard That Makes It Work
USB Power Delivery negotiates voltage and current over USB-C so the bank can pull more than the old 5V limit. If you’re curious about the standard itself, the USB-IF PD overview outlines how higher power modes enable faster charging when both sides support them.
Good Cable, Fewer Surprises
Use a certified USB-C cable rated for the wattage you plan to push. A worn or out-of-spec cable can reduce power, cause heat, or trigger negotiation drops that stretch the clock. If your adapter supports 30–65W PD, pair it with a cable rated for that range.
Why Your Time Might Be Longer Than The Chart
Several real-world hiccups can add hours. Here’s how to spot them and fix them.
Low-Watt Wall Adapter
Older 5V/2A bricks only deliver about 10W. On a 20K pack, that sets you up for 8–10 hours. Swap in a PD charger and the time falls fast.
Charging While Recharging
If a phone or tablet is sipping power while the bank is refilling, net power into the cells drops. Unplug devices while topping the bank for the fastest turn-around.
Weak Or Mismatched Cable
A cable rated for phones might carry 15W fine but falter at 30–45W. If the display on your bank shows low input or it cycles between fast and normal, try a higher-rated cable.
Cold Garage Or Hot Car
Lithium cells dislike temperature extremes. Cold slows the chemistry; heat triggers protection that throttles input. Room-temperature charging keeps speeds steady.
Practical Setups For Popular INIU Sizes
Use these pairings to land in the fast windows shown earlier. They’re simple and repeatable at home or while traveling.
| Charger Wattage | 10,000mAh Approx | 20,000mAh Approx |
|---|---|---|
| 10–12W (5V/2A) | ~4–6 hours | ~8–10 hours |
| 18–20W PD | ~2–3 hours | ~5–6 hours |
| 30–45W PD | ~1.5–2.5 hours | ~3.5–5 hours |
These ranges assume the bank accepts the listed input tier. Some budget models top out near 18–20W on input, so stepping up to a 45–65W adapter won’t speed them further. Higher-end units that advertise bigger inputs can benefit from stronger adapters.
Step-By-Step For The Fastest Refill
1) Check The Bank’s Input Port And Rating
Look for a USB-C input and a PD logo or spec line on the product page or box. If the model supports PD in/out, it can negotiate higher power when paired with a PD wall adapter.
2) Match Or Exceed That Rating With Your Adapter
A 30W PD adapter pairs well with most 10K and many 20K models. For larger banks that accept more, a 45–65W unit trims the wait further.
3) Use A Proper Cable
Grab a cable rated for the target wattage. Keep a spare in your bag so you’re not stuck on a slow lead.
4) Plug Directly Into A Wall Outlet
Power strips with crowded sockets or flaky travel adapters sometimes cause negotiation hiccups. A direct wall plug keeps PD steady.
5) Don’t Pass-Through Charge
Some banks allow pass-through, but it extends the time. Let the bank fill first, then charge your phone.
A Quick Note For Air Travelers
Portable chargers are spare lithium batteries. Aviation rules require them in carry-on only. If you’re flying soon and want the current language, the TSA power bank page lays out the carry-on rule with watt-hour limits and safety tips. Keeping the bank’s Wh label visible and terminals protected helps you breeze through screening.
Troubleshooting Slow Or Stuck Charging
Input Stalls Near A Low Number
Swap the adapter first, then the cable. If the bank has an LED or numeric display, watch whether the input rises when you change gear. A stable PD handshake should hold steady above 15W on compatible models.
Percent Jumps, Then Creeps
All lithium packs slow near the top to protect the cells. If you’re rushing out the door, unplug at 80–90% to save time. You’ll gain most of the usable energy in the earlier, faster phase.
The Bank Feels Warm
Warm is normal; hot isn’t. Move to a cooler spot, remove any case or pouch, and give it room to breathe. Heat triggers throttling, which stretches the clock.
How This Guide Was Built
The timing bands here combine capacity math (Wh), PD input tiers common to INIU models, and the maker’s own guidance on charge rates for 10K and 20K banks. We cross-checked with industry-standard USB-C PD references and with retail listings that reflect PD 3.0 and QC 4+ support on current units. If your specific model publishes a higher input spec than the ranges shown, you can expect the low end of the time window with the right PD adapter.
Bottom Line Timing Picks
10,000mAh INIU
Use an 18–30W PD charger and a solid USB-C cable. Plan on ~2–3 hours from near empty to full when the bank isn’t powering a phone at the same time.
20,000mAh INIU
Feed it with 20–45W PD. Budget ~4–6 hours for a full refill. If your adapter is only 10–12W, you’re looking at most of a workday.
27,000mAh INIU
Pair with 30–65W PD. Expect ~5–7 hours, depending on how close your adapter is to the bank’s rated input, plus temperature and taper near the top.
Match capacity with a suitable PD adapter and cable, keep the setup cool, and avoid pass-through while refilling. Do that, and your INIU pack will be ready again in the time windows above without guesswork.