Netbook makers face a challenge when trying to develop machines that are both light weight and whcih get decent battery life. Because batteries aren’t exactly light. Many netbooks come with three cell batteries, which weigh around half a pound or less. Mini-notebooks with 6 cell batteries weigh a bit more, but get as much as twice the batery life. And the 4-6 hours of battery life you get from a netbook with a 6 cell battery like the MSI Wind U100, Asus Eee PC 1000H, or Samsung NC10 is probably enough for most people.

But there are always a few folks who want even more. And for those folks, there are 3rd party batteries that promise 7-10 hours of use. They often have as many as 9 or 10 battery cells, and promise to provide up to 12000mAh of juice. They’re big, and kind of ugly, and in some cases capable of increasing the weight of your netbook by as much sa 25% to 50%. But if they let you type away for 10 hours, who cares, right?

Well, that’s the catch. Sometimes things that sound too good to be true really are. A few weeks ago Liliputing reader Scott Kuban picked up a high capacity, 12000mAh battery for his Eee PC at what seemed like an amazing price of just $62. After charging up the battery and running a few tests he found that he actually got less battery life from the new battery than he did from his standard 6600mAh battery. He contact the retailer’s customer support department, but the response has been less than satisfactory.

So what gives? It’s possible that the battery is actually made up of recycled batteries that aren’t capable of holding a full charge. And that would mean you get a larger, heavier battery that isn’t even as good as the standard battery. It’s also possible that this is just a single defective unit, but the lesson is clear: buyer beware. If you’re picking up accessories for a netbook, there’s always a chance that third party items aren’t going to work as well as accessories provided by your computer’s manufacturer. That’s part of the reason they’re so much cheaper.

On the other hand, if you’re willing to take the risk, 3rd party manufacturers are taking the lead on high capactiy 9 cell batteries, while I’m not aware of any netbook maker that sells such a super high capacity battery. Here are a few examples:

• 9 cell 6600mAh Acer Aspire One battery from Amazon via Eee PC.net
• 11200mAh Battery For ASUS EEE PC 701from Amazon
• MSI Wind batteries on eBay
• Eee PC batteries on eBay
• Acer Aspire One batteries on eBay