As diligent as you may be with keeping your gadgets fully charged at all times, you may not always have access to wall outlet to charge your cell phone or some other portable electronic device. That’s why having one of these portable battery chargers can come in so handy, especially when you’re on the road and away from your home base.

The Griffin TuneJuice is a portable power pack that can be used to charge the Apple iPhone or iPod (any model with a standard dock connector), giving you that extra bump in battery life when you don’t have a chance to tether your Apple product to the wall. There are other similar power packs on the market that can be recharged through a USB port or wall outlet, but the TuneJuice for iPhone and iPod takes on a different approach.

The pack itself holds no electricity on its own. Instead, you insert four AAA batteries and the energy contained within those batteries can be transferred over to your iPhone or iPod. On the surface, this may not sound like the greenest solution, because you may feel inclined to go through disposable alkaline batteries. However, you could very easily use the TuneJuice in tandem with rechargeable NiMH batteries instead. The ability to use disposables just adds to its versatility.

Using the provided AAA batteries, you can expect one top-up to provide up to 24 hours of music, 6 hours of video, 2 hours of talk time, or 1.5 hours of web access.

The Griffin TuneJuice for iPhone retails for US$29.99 and is available wherever most iPhone accessories are sold.