Will a Qi2 puck spacer charge through 4mm case and fit Pixel Fold 2

Part of our guide on compatibility of magsafe mounts

The short answer: will a Qi2 puck spacer charge through a 4mm case

A qi2 puck spacer for charging through 4 mm case can work, but you have almost no margin left. Most Qi2 links stay efficient to about 5 mm total gap measured from coil to coil, including the 4 mm case, the spacer, and any air or fabric. Add a typical 1.0 to 1.5 mm spacer and you sit right at that ceiling. That is why some setups charge fine and others just heat up.

We see this at the gym and in the car. Phone snaps on, light comes on, percent barely moves. Heat builds in the case. That heat is the clue. Coupling is weak, power folds back, and the phone protects itself. Alignment matters as much as thickness. Qi2 is stricter than old Qi because it expects magnets to hold the coils centered.

So the verdict is conditional. If your 4 mm is a true, even 4.0 mm plastic or aramid and your spacer is thin and centered, Qi2 will usually connect at 5 to 7.5 W and hold. If the case is 4 mm plus a camera lip that adds air, or the spacer is 2 mm, you will see slow or stopped charging. Measure before you buy.

• Even 4 mm plastic: often OK with a 1 mm spacer if centered
• Rugged 4 mm with ridges or kickstand: usually too much gap
• Metal ring or card wallet in between: blocks charging entirely

Distance: why 4mm plus a spacer pushes Qi2 to its limit

Wireless charging is a short air transformer. Two flat coils talk through plastic. Field strength falls fast with distance, roughly with the cube of the gap once you pass a few millimeters. Vendors tune Qi2 for about 5 to 6 mm of separation under ideal alignment. Past that, efficiency drops and heat rises at the same input. Your 4 mm case already eats most of that budget. People in this spot often ask about placing magnetic pouch on painted gym uprights as well.

A puck spacer does not amplify power. It lifts the puck to reduce wobble and to center the magnets. Done right, it trims 0.5 to 1.0 mm of air that a recessed puck would otherwise add. Done wrong, it adds height. A 2 mm tall puck plus a 4 mm case gives 6 mm before you count the phone's own glass and internal gap. That is outside the sweet spot.

Material matters too. Plain TPU, PC, or aramid at 4 mm is mostly invisible to the field. Cases with metal kickstands, pop mounts with screws, or magnetic plates that are not Qi2 rated detune the link. We have seen a single steel plate add the effect of another 1 mm of distance. If your case has metal, remove it or pick a different case for charging.

Temperature tells the truth. Qi2 will throttle when the coil hits about 40 to 45 C at the surface, depending on phone. If the back feels warm within five minutes and charge rate stalls, gap or metal is too high. Cool and slow climb is normal at the limit. Hot and flat is not. There is more on keeping phone secure while charging in a separate guide.

Alignment: why Pixel Fold 2 needs the puck in the right place

Compatibility of MagSafe alignment puck with Pixel Fold 2 comes down to where the coil sits. The Fold 2 charges through the outer cover panel when the phone is closed, and through the same panel when open. There is no coil under the inner flexible display. If you center a puck on the big inner back, you miss by 15 to 25 mm and get nothing.

Qi2 and MagSafe pucks use a ring of magnets to pull the coils into 1 to 2 mm of center. That works only if the ring is placed over the real coil center. On Fold 2 the center is offset toward the cover screen, not the hinge. Hold the phone closed, find the middle of the outer glass top to bottom and side to side, then bias it very slightly toward the camera bar. That is the spot.

Foldables add two quirks. First, the outer glass may have a slight curve or camera bump that rocks the phone. A spacer with a shallow guide lip stops rocking and keeps air under 0.5 mm. Second, the magnets feel weaker because the coil area is smaller and the phone is heavier on one side. A strong N52 ring helps hold, but it does not fix a 4 mm gap. Distance still rules. We go through enable laptop webcam step by step elsewhere on the site.

We test alignment without guessing. Put the puck on, watch the charging icon, then nudge 2 mm in each direction. Note where it starts fastest. Mark that center with a tiny dot on the case. If the fastest spot is not where the spacer puts you, move the spacer. Do not add tape to cheat height. Height is your enemy at 4 mm.

• Charge closed: coil under outer cover, centered on that panel
• Charge open: same outer panel, phone face down on puck
• Inner display side: no charging, magnets may still stick

At 4mm your case already uses up most of the gap Qi2 allows, the spacer decides if it charges or just gets warm.

Setup: how to fit a Qi2 puck spacer and test it at 4mm

You need numbers before parts. Measure case thickness at the coil center with calipers or a ruler and a straight edge. Note the 4 mm reading and whether the camera island lifts one corner. Then measure the spacer height with the same tool. Add them. If the sum is over 5.2 mm, expect throttling unless alignment is perfect and the case is simple plastic.

Clean and dry the case. Adhesive holds only on a flat, warm surface. We wipe with isopropyl, let it flash off, then warm the case to room temp. Cold plastic in a winter garage gives weak bond and later slip. Slip adds air, air adds gap, gap adds heat. That chain is why mounts fail on treadmills.

Place the spacer, test, then commit. Do not press hard until you know the center. Magnets will tell you when you are close. The phone should snap without hunting. If it slides before it snaps, the ring is weak or off center. You want a crisp click, not a drag.

1. Measure case at coil center and write down the mm, then measure spacer height and add for total gap.
2. Find coil center on Fold 2 outer panel and mark it lightly with tape.
3. Set puck and spacer dry without peeling adhesive, power the puck, and check charging starts within 2 seconds.
4. Nudge phone 2 mm up, down, left, right and note where percent climbs fastest over 3 minutes.
5. Peel and stick spacer at that best center, press 30 seconds, wait 30 minutes, then retest for heat and steady charging.
6. If back exceeds warm to touch in 5 minutes or charge stalls, reduce total gap or change case.

Options: which puck spacer clears 4mm and which does not

At 4 mm you want the thinnest spacer that still gives a positive lock. A tall spacer that looks premium on a thin case hurts you here. Look for Qi2 certified pucks where the spacer is really a 0.8 to 1.2 mm ring that registers the puck, not a 2.5 mm pedestal. The certification matters because Qi2 checks that the magnet array does not push the coil away as it pulls.

We group options by job, not by brand. The pick is a low-profile Qi2 ring spacer with a chamfered edge. It adds about 1 mm, centers within 1 mm, and keeps the phone from rocking on a camera bar. The runner-up adds a guide lip for gym racks where the phone is slammed on between sets. The budget is a plain thin ring with no electronics for testing. It tells you if your case can pass at 4 mm before you spend more.

Avoid three kinds at this thickness. Thick pucks over 2 mm tall, pucks with built-in metal kickstands, and universal plates that claim to make any phone MagSafe. Those plates add distance and often use the wrong magnet polarity for Qi2. They may hold the phone but break the handshake. Hold is not charge.

Check listings for what sellers actually print. You will rarely see total gap. You will see case thickness, spacer thickness, and Qi2 certified. Add the first two yourself. If a listing hides thickness, skip it. A shop that will not state mm has not designed for 4 mm.

Limits: who should skip a spacer and change the case instead

A spacer is not a fix for every 4 mm case. If your case is 4.5 mm or more at the center, or it has a built-in metal kickstand, wallet, or hinge armor that crosses the coil, no spacer makes it efficient. You are asking Qi2 to jump too far and to fight metal. Swap to a 3 mm or thinner Qi2 friendly case for charging days and keep the tank case for trail rides.

Fold 2 users have a second limit. If you plan to charge while the phone is open and propped, the inner hinge side lifts and adds air. The phone rocks, gap grows to 6 mm at one edge, and charging stops. Charge closed on the outer panel with the spacer doing the alignment. Open use is for viewing, not for power.

Gym heat matters too. A phone left on a puck in sun through a window or on a hot treadmill deck throttles sooner. At 4 mm you already run warm. Add ambient 30 C and you cross the throttle point in minutes. If your setup lives in heat, favor the thinnest case and the thinnest spacer, or use a short cable for that session. A cable is not elegant, but it is cool and fast.

We would skip the spacer entirely when the case is thick and textured, when you need to charge through a wallet, or when the mount vibrates a lot. Vibration walks the phone off center by 1 to 2 mm and you lose coupling. In those cases a wired USB-C cradle or a thinner everyday case is the honest answer.

FAQ

We run phones on Qi2 pucks on racks and bikes daily, so we measure gap and mark coil centers before we trust a setup.