Did you know that you can get special iPhone battery cases that double your battery life? When I first learned about this ingenious invention, my first thought was, “Awesome! Now my dad will stop teasing me about my phone always being dead because I use it too much.” Even though I’ve explained to him several times that smartphone batteries have notoriously short-lasting batteries, I must confess that he might be right about my usage habits! For both regular and heavy phone users, running out of battery while out and about is a daily concern. That’s why I find these battery cases so handy – they can offer peace of mind both against battery drainage and accidental damage. You can either use them all the time (as a case and a battery-life extender) or you can simply keep them in your bag for those times when your battery runs out. When you want to buy such a case, you need to take into account several things like design, quality and battery capacity. Let me tell you few interesting things about my top three battery cases. 1. Mophie Juice Pack Plus & Mophie Juice Pack Air – compatible with iPhone 4 and 4S Recommended and sold by Apple itself, the Mophie Juice Pack Plus battery case will double the time you can talk or listen to music on your iPhone 4S or iPhone 4. It’s quite bulky but provides great protection, so if you want to keep your iPhone safe and use it heavily, than this case is for you. It comes in lots of colours – including blue, pink, purple, red, black and yellow. Mophie Juice Pack Air version is thinner but also has a smaller battery capacity – a 1600mAh capacity against the 2000mAh capacity of the Plus. Mophie Juice Pack Helium Battery Case – compatible with iPhone 5 The Mophie Juice Pack Helium was the most eagerly awaited battery case for the iPhone 5. It is even slimmer than the Air version for iPhone 4S and iPhone 4 and boasts a 1500 mAh battery that extends your talk-time by up to 6 hours. It comes with a micro USB port to take the place of the Lightning connector, which handles charging and data syncing just fine. This Mophie battery case is thin, light, looks good, and will bring you that extra battery juice when you need it. 2. Third Rail Slim Case and Smart Battery System – compatible with iPhone 4, 4S and 5 If you want extra battery life and a very slim case, then this could be for you! The battery capacity (1250mAh) is less than the Morphie models above, but it is designed so that the case and the battery can be bought separately, which is nice because you can detach the battery when you don’t need it in order to keep the case slimmer. 3. Exogear Exolife Rechargeable Battery Case – compatible with iPhone 4 and 4S Exogear promotes this as the “world's thinnest and lightest battery case” for the iPhone 4. The Exolife is a two-piece case, containing a dock-connector base with a battery back plate, and a plastic bumper that snaps over your iPhone and the back plate. It sports a 1500mAh battery which gives you about seven additional hours of talk time. I hope you like these cases – they’re my top tips when it comes to battery cases because they bring tons of extra battery juice, they feel comfortable in the hand and aren’t bulky. Still, my very favourite one is Mophie Juice Pack Air. How about yours? Share your thoughts with us and you can win a £30 voucher that you can use for Lovefone repairs.