The Best iPhone 4S External Battery?

iPhone batteries are pretty good but there will be times when you need more juice to get through the day or for those long trips. I have been using a New Trent battery pack for years, with good results, but there are plenty of other devices that can deliver some extra power when you need it.

A battery case like the Mophie will double the time between recharges and, if you like the design and don't mind the extra bulk, it can be a perfect solution.

The big advantage of a case is that there is nothing extra to carry (or lose). There are also no wires to get tangled.

New Trent battery technolgy is reliable and the power they pack into a small space is impressive.

The 5000 mAh (milli-ampere hours) ifuel, pictured right, is probably the most popular single external battery in the US. It carries roughly three times as much juice as the i4s internal battery and that is enough to power movie viewing for 25 hours straight.

If you want a huge power resource there is the iCruiser IMP1000 which delivers 11000mAh. That might be what you need for a week camping in the mountains!

Both devices work with most kinds of iPod and iPad as well as older iPhones. Many of the more popular non-Apple phones can get a charge too, including HTC, Samsung and Blackberry (check individual models to be sure).

If you invest in some special adapters, these batteries will power most game consoles too.

The matte black case is one of the most practical around. It is a great fit and the soft finish is more or less scratch proof as well as offering good shock absorbtion.

It has a 1700 mAh battery that, in theory, should recharge the i4s completely. In practice, it will give you at least 60% which means a very substantial increase in times between recharge.

Charging is via the standard Apple mini USB cable and both case and phone battery can be charged simulataneously- no need to remove anything.

The standard matte black case has recently been joined by a glossy white version. The looks will appeal to many people but bear in mind it is nowhere near as scratch proof and a lot more slippery than its cousin.

No name products like this battery case do not always inspire confidence. The manufacturers sensibily offer a three guarentee. There are also plenty of happy users around.

A plus with this case is supplied USB cable and screen protector.

The LED display lets follow the progress of charging.

Mophie battery case are well known and highly repected. They blazed a trail that other makers have followed. Construction is top quality with many color choices.

The orange banded case right might not suit everyone but recently caught my eye as unusuall and striking.

Mophie cases are little less powerful than the two desribed above but deliver a similar recharge to the i4S internal battery.

Something like the Puregear battery device is not going to add a huge amount of use time to an iPhone but it is wirefree and easy to carry. It is also inexpensive.

You can use it with confidence too, since it is Apple certified.

Expect about one hour of extra usage.