The short answer
- 5,000 mAh is the everyday size: light enough to leave on the phone and enough for most of an iPhone 17 battery.
- 10,000 mAh is for travel days: roughly twice the weight, with about one full charge of a large phone.
- Qi2 certification matters more than the wattage on the box. It guarantees magnetic alignment and tested safety; an uncertified pack that claims 25 W often cannot sustain it.
- Heat decides real speed. A magnetic battery pack that slows down when warm is protecting your phone, not underperforming.
Qi2 and Qi2 25W explained
Qi2 is the wireless charging standard of the Wireless Power Consortium (WPC) that adds a magnetic ring to Qi, so the coils lock into the same position every time. The first version charges at up to 15 W. The newer version, branded Qi2 25W (technically Qi v2.2), raises that to 25 W, and every Qi2 25W product is magnetic.
The whole iPhone 17 family supports Qi2 25W charging, according to Apple's published specifications. iPhone 16 models (except the 16e) can reach 25 W too, with iOS 26 or later and a sufficiently powerful adapter on certified chargers.
Two practical points for anyone buying a magnetic battery pack:
- Check the WPC database. A product may only carry the Qi2 logo once it is certified. If a magnetic battery pack claims Qi2 but is not listed, treat the claim with caution.
- Peak wattage is not average wattage. A pack may start at 25 W and step down quickly as it warms. What you feel is the time to add 50%, not the first-minute peak.
Our own Snap magnetic battery packs charge at up to 15 W and are not Qi2 certified, so we do not put the Qi2 mark on the product, the box or the listing.
5,000 vs 10,000 mAh
As with battery cases, the number on a magnetic battery pack is usually the rated capacity. Our 5,000 mAh pack measures 4,500 mAh on the bench. The difference between the two sizes is mostly about weight and how often you will actually carry it.
| Spec | 5,000 mAh class | 10,000 mAh class |
|---|---|---|
| Rated energy | about 18.5 Wh | about 37 Wh |
| Typical weight | about 120 g | roughly twice as heavy |
| Best for | Daily use, leaving it on the phone | Travel, festivals, long shifts |
| Air travel | Carry-on only, well below 100 Wh | Carry-on only, well below 100 Wh |
How much charge you really get
The same physics applies to every magnetic battery pack: energy is lost in voltage conversion and across the wireless coil. On our bench about 58% of the energy the cell delivers reaches the phone battery over wireless. Using the published iPhone 17 battery sizes, that gives these estimates:
| Phone | 5,000 mAh pack (4,500 mAh measured) | 10,000 mAh pack (about 9,000 mAh measured) |
|---|---|---|
| iPhone 17 | about 70% | about 135% |
| iPhone 17 Pro Max | about 50% | about 100% |
The 10,000 mAh column assumes the same rated-to-measured ratio as our 5,000 mAh cell. Use the wired USB-C port instead of wireless and more of the energy reaches the phone, because the cable skips the coil.
Magnet hold and case compatibility
A magnetic battery pack needs either a bare iPhone with built-in magnets or a case with a magnet ring. Thick cases without magnets weaken the hold and push the coil out of alignment, which turns energy into heat.
- Hold strength: the pack should not slide when you hold the phone sideways or take it out of a pocket.
- Alignment: a good ring snaps to the same position every time; that is what keeps efficiency and temperature stable.
- Case design: a thin case with a built-in ring keeps the phone slim on days when the pack stays at home.
Heat: the hidden trade-off
A magnetic battery pack sits directly on the back of the phone, and both get warm while charging. Good packs measure temperature and reduce power before the phone has to. That is the main reason two packs with the same label can add charge at very different speeds. To keep things cool:
- Take the pack off during demanding games or navigation in a hot car.
- Do not leave the phone and pack in direct sun or under a pillow.
- If speed matters, connect a USB-C cable between pack and phone.
Ports, pass-through and recharging the pack
Look for a USB-C port that works in both directions: to recharge the pack and to charge the phone by cable. Ours supplies up to 20 W over USB-C. Pass-through charging, where the pack charges the phone and itself from one wall adapter, is convenient at night. A simple charge indicator saves guessing how much is left.
Safety and air travel
A magnetic battery pack is a spare lithium battery for airlines: it belongs in your carry-on, never in checked luggage. A 5,000 mAh pack is about 18.5 Wh and a 10,000 mAh pack about 37 Wh, both far below the 100 Wh limit. For any pack, a reputable maker should be able to show a UN 38.3 test summary, an IEC 62133 report and an SDS.
Buying checklist
- Qi2 or Qi2 25W claims are backed by a listing in the WPC database.
- Both rated and measured capacity are stated.
- The pack holds firmly and works with your case.
- There is temperature control and a two-way USB-C port.
- The weight suits how often you will carry it.
- UN 38.3, IEC 62133 and SDS are available on request.
Still deciding between a pack and a case? Read our magnetic battery pack vs battery case comparison.
Frequently asked questions
Is Qi2 25W faster than a normal magnetic battery pack?
It can be, on phones that support it and when the pack is certified. In practice heat limits sustained speed, so a certified pack that manages temperature well is often faster over a full top-up than an uncertified one with a higher peak claim.
Does a magnetic battery pack work with a phone case?
Only with a case that has a built-in magnet ring, or a very thin case. Otherwise the pack holds poorly and wastes energy as heat.
How many times can a 10,000 mAh magnetic battery pack charge an iPhone 17?
About once and a third by wireless, based on a measured capacity of around 9,000 mAh. A cable gets you a little more.
Can I leave a magnetic battery pack on my phone all day?
Yes. It will top the phone up as needed. Take it off if the phone gets hot, for example during gaming or in direct sun.