Like most things, the title of “best iPhone 6 battery case” is subject to change whenever something new and great shows up to challenge existing options, and as the iPhone 6 is still young, we’re expecting a lot of jockeying for position over the next few months. The latest real contender comes from iBattz, maker of some of the best iPhone battery cases I’ve tested. Refuel Invictus for iPhone 6 ($100, aka Mojo Refuel Invictus) is the first iPhone 6 case to include a great feature from some earlier iPhone 4/4S and 5/5s cases: removable, replaceable batteries.

Using solely the items in its own box, Refuel Invictus delivered the largest recharge I’ve seen yet for the iPhone 6: 127%, or a full recharge plus an additional 27%. That might be enough to justify the asking price for some people. But you can also add a second battery and external USB charger for $25-$30 more. If you’ve been hunting for a slim battery case that can keep your iPhone running endlessly, this might be the most cost-effective way to do it.

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Key Details:

  • Wraps a 3200mAh battery in a hard plastic case that feels like a thin, long iPhone 3G/3GS.
  • Fully recharges the iPhone 6 from dead, plus an extra 27%.
  • Spare batteries are sold separately for $25-$30.
  • Batteries come with a standalone USB charger.

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Superficially, Refuel Invictus doesn’t look much different from the scores of other matte black plastic iPhone 6 cases out there. Like almost everyone else, iBattz includes both a headphone port extender and a micro-USB to USB recharging cable, both of which are necessary to use its ports. It’s only when you disassemble the case down to the components — particularly the removable rear panel and the bright orange removable battery — that it starts to look unique. The entire top of the case around the rear camera hole also detaches to aid with iPhone 6 insertion.    

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When Refuel Invictus is reassembled, the iPhone 6 looks a lot like a thinner, taller iPhone 3G/3GS, gaining soft tapered curves on its edges. There’s nothing particularly beautiful about the case: the plastic feels a bit thin, seams are evident, and there’s an inconveniently small power button hidden on the bottom. Similarly, the side ringer switch hole is tiny, and though iBattz’ modestly-elevated button covers work mostly as expected, the buttons barely move when pressed. On the other hand, only half of the current iPhone 6 battery cases include any type of button coverage, and no other option can swap batteries on the fly. So despite ergonomic and aesthetic considerations, this is one of the more protective and versatile battery cases around.

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If Refuel Invictus has any really strong suit, it’s battery performance. The 3200mAh cell has 1A input and 1A output, enabling it to recharge itself and an iPhone 6 with acceptable speed: it took around 2 hours and 15 minutes to bring a dead iPhone up to 100% power, with an additional 34 minutes to add an extra 27%. This trumps iBattz’ own promise of a 120% recharge, as well as the 121% performance we saw from Incipio’s earlier offGRID Express. While offGRID Express has a $20 lower MSRP and even better street price, it doesn’t have the ability to swap batteries. iBattz sells a spare battery pack and recharger for $30, with a $5 savings if you buy it with Refuel Invictus. This is somewhat steep, and extra batteries should really be offered without the charger, but it’s a less expensive option than buying a second iPhone battery case.

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Refuel Invictus isn’t the fanciest or least expensive iPhone 6 battery case out there, but what it offers instead is pretty compelling: the strongest iPhone 6 recharging power I’ve yet seen in any battery case, combined with the ability to swap batteries on an as-needed basis. It’s also thin and light — some might say to a fault — with familiar, iPhone 3G/3GS-style contours that will feel comfortable in a pocket or hand. My advice would be to consider it if the swappable battery option really appeals to you, particularly if the street pricing comes down a little. Otherwise, you’ll get nearly equivalent performance at a lower price from the offGRID Express.

Manufacturer: iBattz MSRP: $100 (Amazon) Compatibility: iPhone 6