My first generation iPod just didn't hold a charge anymore. A timely article on Wired about Newer Technologies 22-hour battery for first and second generation iPods came my way...
Available from iPodWorld for £40 plus post and packaging, the Newer Technology Li-polymer 2100 mAh 3.7V battery for 1st and 2nd generation iPods is a replacement for the Sony-made original. Like many original iPods, mine would play for a few hours—but only if you'd just charged it. If it had sat around for more than a day or two, the juice would have drained completely. No amount of resets or iPod updates seemed to solve this.

Opening the case
I soon learned why the DIY option is significantly cheaper than Apple's return-to-base battery replacement program. The iPod is one tough nut to crack! The metal back is held in place by 12 plastic clips:

It was not easy to prise the front from the back; the supplied tools are made of a soft plastic the soon disintegrated:

Eventually I resorted to a small-tipped metal screw driver in order to maintain the gap I had made, and traded a gentle approach for frustrated aggression. It became easier once I knew the how and the how much (force). Easier, because I had to do it several times...
Unwelcome icons
On connecting the new battery I saw a succession of icons on my iPod screen, only the first of which was familiar:

The meaning of these icons can be found here. The hard drive made some disturbing noises. I tired multiple resets. I charged from the power adapter. I charged from the computer. I unplugged the battery and did it all again. And again... Eventually, after a spell charging the iPod with it's original battery back in place, my iPod came back to life. I reinserted the Newer battery and low-and-behold it began charging via the wall socket.
How long does it last?
After an overnight charge I set my iPod to play my entire library (on "shuffle"). At 17.5 hours it was going strong, displaying a half-full battery. When I next looked, at 23 hours, it was dead. So the manufacturers claim for a 22-hour playtime may for once be the truth. I just wonder how many weeks or months it will hold a 22-hour charge for, before going the same way as the original battery.
Update 03.08.05: The New Technologies battery lasted only 10 months, refusing to charge after this time.
Update 09.08.05: After confirming that a hard reset didn't solve the problem, Customer Service decided the battery must be defective and offered to replace it on proof of purchase. After mentioning I was in the UK I was informed that I would be liable for return to and from international shipping, and that this would likely exceed the cost of the battery. Luckily I kept the Apple-supplied original—which charges fine—it just doesn't hold it. Nothing a car charger won't fix. Moral of the story? Beware of "cheap" solutions to your iPod battery problems.
Update 26.08.05: Other World Computing (not exactly sure what their relationship is to Newer Technology) had a change of heart, saying "After reviewing this with the customer service manager, we have decided to ship you out a new battery (free of charge). We have had a lot of good reults with our batteries and stand behind them 100% it's certianly not common for them to fail so soon." The replacement battery is now installed and so far so good. It's nice to find a company that believes in its product enough to back such conviction with responsive customer service. Well done Newer Technology/ Other World Computing.
Update 23.12.05: The iPod is dead again, with the new battery failing to take charge after only 4 months. I've tried re-setting the iPod etc to no avail. RIP.









Just Venting.
Wondered if anyone else had this problem.
I had a similar problem with my 5th gen video ipod. It got down to a 45 minute maximum playing time, then just wouldn't turn on at all for anything. So I figured it was the battery, ordered a replacement ($30), and changed it myself thanks to the help of some video tutorials (wasn't so bad, really).
It gave all the right signs, lit up, charged for 4 hours, and the stopped playing after a few minutes. I charged it more--over night--but nothing is helping. A few seconds after I take it off a charger--wall or car--it shuts down, and won't start up again. I couldn't restore it because it would sometimes not even turn on when connected to the USB cable, or would just say 'low battery' (grey and black screen instead of the normal color screen) and not have even juice to even be recognized by iTunes.
I had to disconnect it from the wall charger and move it to the USB INSTANTLY, and it would only stay on for about 10 seconds, if that. I restored it, and it hasn't helped.
Thanks a bunch, Apple, for the planned obsolescence. The Apple store here doesn't even offer battery replacement as an OPTION. They want you to recycle yours for 10% off a new one (great, 25 bucks on a 300 dollar ipod), or buy a refurbished one for $130 that is only guaranteed for 90 days. $130 ?!? That's robbery!
Hope the venting helped LJL? Sounds like the battery may be good but something else (hardware or software) is causing it not to charge; that may have been my issue too. Maybe you can leave yours connected to an in-car charger and still get use out of it on the road. Or, backup to it and use it like a portable drive.