Does your iPhone's battery give up the ghost before you finish watching that movie or posting on Facebook?
The easy fix is a specialised accessory known as a battery case. That name pretty much says it all: it's an iPhone case that contains its own secondary battery to complement the iPhone's. They dramatically boost the number of hours you'll get from your iPhone before plugging it in for a recharge.
One downside is they add bulk and weight to the phone, making it about 50 per cent thicker and twice as heavy.
It won't slide as gracefully into a pair of skinny jeans but it's still small enough for a pocket or purse.
The Mophie Juice Pack Plus boasts a battery rated at 2000mAh, compared with the 1400mAh of the iPhone 4 and 4S. This means you can run your iPhone for almost 2½ times longer than normal. The Juice Pack Plus case is also very solid, yet surprisingly comfortable, and with a choice of six colours, could almost have been made by Apple itself.
Although the Padacs Power Case 16 offers a lesser-rated 1600mAh battery, that's still sufficient to more than double the battery life of your iPhone when you're out and about.
The glossy-black plastic case looks appealing but feels less sturdy than the Mophie.
An undersize hole for the iPhone's camera causes a ''whitewash'' effect on photos taken with the flash, which rules out the Power Case if you regularly take night-time snaps.
The Mophie Juice Pack Plus is a superior product but its $US100 price tag, compared with just $25 for the Padacs Power Case 16, will result in plenty of iPhone users settling for the cheaper option.
Mophie Juice Pack Plus
Padacs Power Case 16