The first time I saw an iPhone 14 Pro Max battery puff up, it wasn’t pretty. Picture this: the phone was lying face down on a granite countertop, slowly, inexorably rocking. The owner hadn’t noticed anything amiss until the telltale bulge started pressing the screen away from its frame. That, friends, is the nuclear winter of smartphone ownership.

And that’s why I approach battery replacements with a surgeon’s precision. This “high-density core strengthening technology” as they’re calling it on this replacement unit…well, it piques my interest. Increased capacity, same form factor? That’s the holy grail. Anyone who’s dealt with the older, standard lithium-ion cells knows: they’re essentially bags of flammable chemicals. The goal is maximum power density within the tight confines of a modern phone. The specs on this replacement are encouraging: listed at 4323mAh, this matches the factory spec of the original battery perfectly. Not a single milliamp-hour more, not a single milliamp-hour less, which is critical for maintaining optimal charging cycles.

Installing it wasn’t a picnic, naturally. You’re essentially performing micro-surgery on a very expensive slab of glass and metal. The adhesive, for instance: It’s notoriously tricky. The iFixit kits offer a decent, if somewhat expensive, adhesive kit with good instructions, which I highly recommend. Don’t skimp on the tools, either. Using the wrong screwdriver, or trying to pry with something other than a spudger? You’ll regret it, believe me. And pay attention to the connector placement; even a millimeter off can fry your logic board.

Testing it afterwards, however, was a genuine pleasure. The charge cycle matched the OEM battery. I ran a few extensive tests: streaming high-definition video, running graphically intensive games and, of course, the dreaded battery drain tests. It held up remarkably well. My usual test scenario is to take the phone from 100% to zero. This battery performed like a champion. As an aside, I always think it’s kind of a shame the battery health indicator is hidden deep in the settings, since it would have been useful for quick overview.

And now the small imperfection I mentioned: this isn’t a fault of the battery per se, but a reflection of the current state of replacement parts in general. The included adhesive strips don’t perfectly match the original. They work, certainly. However, a true, perfect fit would require the kind of precision only the original factory assembly can provide. But it’s a minor compromise for saving a few hundred dollars.

For the DIY enthusiast or someone looking for an affordable fix? This is a solid, and cost-effective alternative to buying a whole new phone. If you are not feeling confident in performing the installation, I recommend you find a reputable repair shop, that’s all. This battery gives a solid performance boost, and with careful handling, it is a very good choice. Now go forth and breathe life back into your phone!