If early adopters of the iPod have found out one thing, it's that the battery life of Apple's portable music player tends to diminish radically with time. If you bought an original iPod on the first day of its release and have used it regularly since, you're likely to struggling with a battery life that's perhaps shrunk to less than an hour – something which makes the product more or less useless.

Of course, you could send it away to Apple and have the battery replaced. However, doing this is a relatively expensive, so it's no surprise that several third parties have begun to offer battery upgrades which can be fitted by you. At much lower cost. One of these companies is Newer Technology, a name that will be familiar for its Mac processor upgrades. What's more, its Ultra High Capacity 2100mAh battery delivers around 20 hours of battery life to any first or second generation iPod, for less than $40.

Fitting a battery to the iPod is one of those things which is much easier to do than you'd expect. Taking the case apart is simply a matter of sliding one of the plastic tools supplied down the crack between plastic and metal parts along the side and bottom of the player. Once this is done, you need to ease the old battery away from the drive underneath, retaining the two adhesive pads which hold the battery in place. Then detach the battery from the small cable which powers the iPod, and fit the new battery, using the old adhesive pads. Clip the metal back of the iPod back into place, and that's it – the new battery is fitted.

We tested the battery by fully charging the iPod then leaving it on to play continuously until it was totally depleted, three times. Using a random set of songs including both short pop tunes and longer classical pieces, we found the Newer Tech battery delivered between 18 and 21 hours of battery life – a considerable improvement over the 40-60 minutes that the original battery had been managing.

Overall, the Newer Ultra High Capacity 2100mAh battery is the most cost-effective way of getting more out of a first or second generation iPod. If it were $50 it would be a bargain: at less than $40, it's excellent value for money. Even if you're still getting a couple of hours of battery life out of an old iPod, it's worthy spending the money simply to watch the faces of friends with the latest model as your two year old machine eclipses the "mere" 12 hours of battery life they're getting. The battery is available through OWC.

Contact IAN BETTERIDGE at ianbetteridge@mac.com.