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I tested this fan-equipped MagSafe charger in a heat wave - and it actually kept my iPhone cool
ESR CryoBoost Foldable 3-in-1 Magnetic Charging Station
pros and cons
- The compact design is perfect for travel.
- The cooling is effective, even in high temperatures.
- It comes with a charger and cable.
- The hinge has a strong "finger-snapping" action.
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Heat waves have hit the US twice already this month, with temperatures in Phoenix hitting 113°F from July 6 to 8, and Salt Lake City and Billings both breaking all-time temperature records on July 12, according to NBC News and Wikipedia's running tally of the 2026 North American heat wave.
But extreme heat isn't just a problem for you. It's a problem for your tech, too.
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Take Apple, for example: The company's official guidance caps recommended charging conditions at 95°F/35°C ambient, with an ideal range of just 62-72°F/16-22°C. Push a device beyond that ceiling, and bad things can happen. At first, the built-in software "might limit charging above 80 percent," which is what's behind the "Charging on Hold" message some iPhone owners see in summer. When the iPhone's internal temperature rises above its normal operating temperature, it's not a bug; it's a feature. Sustained temperatures above 95°F can permanently shorten battery lifespan.
Since we've also been getting heat waves in the UK, it's been the perfect opportunity to test a charger that claims to be able to keep your devices cool. The ESR CryoBoost Foldable 3-in-1 Magnetic Charging Station is a 25W Qi2.2 charger with small fans built into the charging pad, specifically designed to combat this issue.
Charging, heat, and what to do with it
Charging creates heat. It's a byproduct of pushing energy into a battery. Remember high school -- energy can't be created or destroyed; it's just turned from one form to another. The process of turning electrical energy into chemical energy (which is what charging a battery is) isn't 100% efficient, and the losses are in the form of heat. Wireless charging adds even more inefficiency on top of that, and those losses show up as heat, too.
All this means that while wireless charging is convenient, it generates a lot of waste heat. This is not normally much of a problem, but when you're under a heat dome, the phone can get toasty.
So, what happens to that heat? It's dissipated into the air. And when you're dealing with room temperature, this works fine, but when there's a heat wave, this isn't enough.
This is where active cooling comes into its own.
And by active cooling, I mean a fan. By adding a fan to the wireless charger, more air can be drawn through the charger, allowing the heat to be better dissipated even when the weather is hot.
ESR hasn't kitted the charger out with one fan -- there's a second fan. One is used to cool the 25W Qi2.2 MagSafe charging pad, and the other is underneath the AirPods charging pad. I've not seen this mentioned in any of the literature, but there's one there.
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These fans are small, yet incredibly effective, and really do chill the charger well. They have fine blades that move a surprising amount of air -- you can feel it -- and they run quietly, so quietly that "whisper quiet" would be an understatement.
But if you have bionic hearing or are someone that's irritated by the quietest of sounds, press the "sleep mode" button on the side of the charger, and that cuts the fans. You don't get active cooling, but you'll sleep.
But ESR has used another trick to cool things down, and it's an effective one. The rear of the wireless charging pad is made from aluminum, and this acts as a big heatsink, pulling the heat from the charging pad and the iPhone and helping to make the fan more efficient.
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There's also a 5W Apple Watch charging puck built into the charger that flips up when you need it. There's no cooling for the Apple Watch puck -- it's not needed. But ESR has supplied little stickers that prevent the Apple Watch from spinning around on the puck. I don't care about the spinning and don't want to bother with stickers that need replacing every couple of months, so I've not bothered with these.
All the charging pads deliver the power that they specify as long as the USB-C charger the station is connected to is 50W or greater.
Flip-phone look
The charger looks like a 90s flip phone and folds down to something not much bigger than my Ridge wallet, making it perfect for travel.
But beware -- it bites. The flip action had enough power to pinch a bit of skin on my finger and bruise it! When it's not snapping my fingers, the hinge on the charger does a fine job of holding the unit at the angle you want -- anything from 0 to 75°, so you can set it at the perfect viewing angle and it stays there.
Oh, and while we're discussing the design of the charger, this one is perfectly stable when loaded with an iPhone, Apple Watch, and AirPods. It still staggers me when I get sent a wireless charger for review and it's unstable once you attach the iPhone to it. When it comes to 3-in-1 charging stations, no one wants a situation where all their precious Apple possessions come crashing down.
Just add - nothing
ESR has thought of everything and has included a neat little 50W USB-C charger! This is great for home or office use, but when traveling, I'll plug it into one of my universal adapters.
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The charger also comes with a 5-foot cable, and it's not some generic cable. No. One end is straight and the other is a right-angle connector, so it fits neatly into the charging station.
A nice touch.
Torture testing
I used the hot weather to test the charger.
I ran it at night, and it kept my gadgets nice and cool. Then I ran it during the heat of the day, and again, things were a little more toasty, but I had no problems with charging being throttled.
Next, a torture test. I put the charger in the car.
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I chose not to put it on the dashboard, as that would have been a crazy test and a bad idea when it was 84°F/29°C outside and the dashboard was in the 180-200°F/82-93°C range. Instead, I chose to be a bit cautious and left it in the shade in the footwell (powering it from a portable power station and not leaving the car idling), but the air temperature there was a hot (for a Brit, anyway) 95°F/35°C.
Surprisingly, the charger did a great job of keeping the iPhone cool enough to charge.
However, after about an hour, I had to pull the plug on the test because the car's internal temperature got to a point I considered unsafe.
But ESR's CryoBoost feature worked amazingly well.
No TEC
Regular readers will probably recall that I've written about TECs in the past -- thermoelectric coolers. They are small squares made of two different semiconductors, and when you pass a DC current through them, one side gets cold and the other gets hot. This happens because the TEC moves the heat from one side to the other, cooling with no moving parts and no refrigerant.
So why not pack one of these into the wireless charger?
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There are drawbacks. One is that the hot side has to dump that heat somewhere, so when the going gets tough, it can actually make a heat problem worse. Another problem is that if the cold side gets too cold and goes below the dew point, condensation can form on the charger and phone.
Not something I want around my electronics.
With the fan alone, ESR says that it can knock the charging temperature down by as much as 10.8°F/6°C, making it a good compromise between a charger that doesn't have any cooling at all and one that uses a TEC.
ZDNET's buying advice
At $99, the ESR CryoBoost Foldable 3-in-1 Magnetic Charging Station is definitely at the higher end of the spectrum when it comes to 3-in-1 charging stations. But this is one of the best that I've tested for handling heat. Yes, you might argue that it's a bit plasticky -- what isn't these days -- but this keeps the weight down and ESR has put metal where it's needed in the form of a heatsink plate at the rear of the MagSafe charger.
Also, there are other nice touches, like a metal grille over the fan beneath the AirPods charging pad to prevent it from sucking up dirt and dust into the innards of the charging station.
With the kit, you get a charger and a decent cable, both of which go a long way to elevate this product to a tier where it's worth the price.
As I said, for my use, this makes a great, super-compact travel charger that's also perfectly suited as a desk charger or one to put on the nightstand. It's small, unobtrusive, and it works.