I'm a big fan of magnetic phone accessories, especially when it involves MagSafe-compatible wireless charging. Portable battery packs are great, but the reliance on cables is not something I will ever be happy about. Switching to wireless charging, and using magnets to keep everything in place, means that problem is eliminated — though it's not ideal that those batteries add a bunch of bulk and weight to your phone.
Belkin's newest magnetic battery pack, UltraCharge Pro Slim Magnetic Power Bank with BoostSolid Cell, helps to eliminate that problem. The "Semi Solid State" battery design is significantly thinner and lighter than you might expect, which makes a surprising amount of difference for comfort. However, that also comes at the cost of overall capacity, which may or not be a dealbreaker.
What the heck is a 'semi-solid-state' battery?
You may be wondering what Semi-Solid-State actually means. The idea of solid-state batteries is nothing new, since those offer power without any of the chemical movements and reactions.
According to Belkin, this "semi-solid" design utilizes a gel-like layer alongside a liquid electrolyte. The company hasn't gone into the specifics of how everything works, but the design enables a slimmer and more compact design, greater longevity and a much lower risk of overheating. That should help improve the overall safety of using these batteries, and considering the clampdown by airlines in recent months, that's definitely a good thing.
Speaking of airlines, Belkin says that the $70 UltraCharge Pro Magnetic Power Bank has been built to comply with standard safety requirements, and the TSA's carry-on guidance. Though this doesn't necessarily mean that you are cleared to use this one in the air. Each airline has their own policies, and you need to be aware of them before you travel.
The battery itself is Qi2 certified, offering up to 15W charging speeds on compatible phones. Wired USB-C charging is also available if you have a cable, with speeds up to 7.5W. The battery itself recharges at up to 22.5W. Naturally, being magnetic, it snaps onto the back of your phone — whether it has built-in magnets or you're using a special case.
Materials-wise, you've got a battery that is a mix of metal and rubber, which is not exactly uncommon in magnetic batteries, though the actual size of the thing is arguably where its biggest strength lies.
How does it compare to my existing magnetic power bank?
The magnetic battery pack I use most of the time is UGreen's 10,000 mAh magnetic power pack. It's a fairly cheap option, which means it isn't officially certified as MagSafe or Qi2 — it's just a regular wireless charger with a MagSafe-compatible connection. That means it's slow, and it has a habit of getting pretty hot.
UGreen's model is 0.79-inches thick, which is more than double Belkin's 0.35-inches. It's also heavier, weighing 7.9 ounces compared to 4.4 ounces for the Belkin. The UGreen battery is actually heavier and thicker than an iPhone 17 Pro (0.35-inches and 7.27 ounces), and only slightly lighter than the iPhone 17 Pro Max (8.33 ounces).
The UltraCharge Pro Magnetic Power Bank is still going to add thickness and weight to your phone. However, it is a lot more comfortable and convenient to use compared to the bulky UGreen option I've been using.
The downside is that it the Belkin has half the capacity of the UGreen. 10,000 mAh is enough to charge just about every phone at least once — and often more. 5,000 mAh doesn't go quite as far, but it's no small amount of power. It's enough to recharge a lot of phones in full, and enough to add a significant amount of power to others.
Personally, while I like to overprepare and make sure I have more than enough energy to keep me going, I'll admit that 10,000 mAh is a bit overkill for most situations. So long as you have enough power to make it through the day, and get back to a home charger, then what does it matter how much of a reserve you have?
In terms of charging and heat, I decided to test the two batteries on my iPhone 17 Pro Max starting at 47% charge. The Belkin battery restored 10%, bringing the total to 57% in that time, while the UGreen battery brought the charge to 54% — a 7% increase. It's not a huge amount of difference, but over the course of many hours that will add up.
As for heat, the Belkin battery definitely felt warmer, but a quick check with a thermal camera saw the temperature peak at just under 95 degrees Fahrenheit. The UGreen battery didn't feel nearly as warm, but the thermal imaging revealed that a small part of the battery had risen to just shy of 97 degrees. That's not a huge difference, but you do have to remember that the UGreen charger is going much more slowly — and I did feel that heat start to add up over extended charging sessions.
Wireless charging is always going to produce some heat if you don't have some sort of active cooling system. The Belkin UltraCharge does get warm, but it doesn't get too hot, which is quite nice.
Bottom line
I really like the Belkin UltraCharge Pro Magnetic Power Bank. Not specifically because it's a semi-solid-state battery, but because it manages to do all the things you need from a portable battery pack. It's slim and lightweight, with the magnetic connection making it incredibly easy to recharge your phone. Plus, the 15W Qi2 speeds mean it's fairly speedy as far as wireless charging goes.
Admittedly, the 5,000 mAh capacity would be enough to make me hesitate on buying one for myself — especially with a $70 price tag. You can buy wired battery packs that offer four times the capacity for similar prices, if not less. Still, you can't fault the Belkin for convenience or comfort, and that premium might be worth it if you regularly find that you need to top off your phone on the move.
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