Mophie Juice Pack Plus Review

Mophie's Juice Pack Air for iPhone 4 impressed us back in September with its minimal bulk and ability to almost double runtime versus the standard Apple battery. Still, there are some power users – or weekend travellers – for whom "virtually double" still isn't good enough, hence the Mophie Juice Pack Plus. Bigger battery, bigger price; is this Mophie good value or overkill? Check out the full SlashGear review after the cut.

The key difference between the Juice Pack Air and the Plus version is the battery: 1,500 mAh in the Air, versus 2,000 mAh in the Plus. For that Mophie charge $20 extra, bringing the Juice Pack Plus to $99.95. In comparison, the iPhone 4's own battery is 1,420 mAh, and while the fourth-gen smartphone generally manages longer runtimes than its predecessors, the tactile charms of iOS often mean users run the phone down well before the end of the day.

Despite the larger capacity battery, the Juice Pack Plus measures and weighs exactly the same as the Air: 5.07 x 2.51 x 0.68 inches and 2.5 oz. Yes, it adds some bulk to the iPhone 4, but it's minimal in practice, and the curved, soft-touch rubber back panel actually makes the Apple smartphone more comfortable to hold.

Around the case there are cutouts for the volume buttons, ringer switch, headphone socket and sleep/power button, as well as a hole at the back for the camera and flash. While there's no docking connector cutout – the bottom edge of the Juice Pack Plus has a button and four LEDs to show battery status – you do get a microUSB port for recharging both the phone and the Juice Pack, as well as sync'ing with iTunes. A physical power switch on the bottom corner rounds out the main controls.

The iPhone 4's speaker on the bottom edge of the handset gets a "virtual speaker box", basically redirecting audio out the front of the case. As on the Air, it does make for louder music playback. Build quality in general is high, and while there's no fascia protection (bar a slightly raised rim around the edge, holding the touchscreen off the table if placed face-down) the rest of the case is sturdy and feels well constructed.

Mophie claim the Juice Pack Plus is capable of boosting iPhone 4 talktime by up to 8hrs on a 3G network or up to 16hrs on a 2G network. Alternatively, you should see up to 7hrs extra 3G browsing time or 11hrs WiFi browsing. Audio playback is boosted by up to 44hrs, or video playback by up to 11hrs. Those numbers all exceed Apple's estimates for the iPhone 4's own battery, usually by at least an hour, suggesting you can more than double usage with the Plus in place.

As with the Air, the Juice Pack Plus can work in two ways. With the Mophie switched off, you can use your iPhone 4's own power until it's close to expiring, and then turn on the Juice Pack to recharge the handset as if plugged into the mains. Alternatively, you can turn the Mophie on straight away and rely on its external power initially, leaving the iPhone 4's internal battery for when the Juice Pack Plus runs out.

Though we tried both approaches, the overall result was the same. With normal use we managed two days with no downtime – several hours longer than the Air had managed to prolong the iPhone 4. Of course, with some judicious use of the Juice Pack Plus' power switch, we were able to prolong the power on offer through into a third day.

Barring the extra $20, we can't see any reason why iPhone 4 owners would opt for the Air over the Mophie Juice Pack Plus. With no bulk or weight compromise, you're getting several hours extra use together with the same protection for the smartphone. Equally appealing to power-users and those making trips during which time they'd rather not concern themselves with toting an AC adapter and finding somewhere to plug in, the Mophie Juice Pack Plus is perhaps the company's best model to date.