The 'Mugen Power' 9-cell battery pack arrived for my Advent 4211 (MSI Wind 'clone') just over a week ago. I had to wait until the weekend before getting to try it out since I wanted to put her though at least 3-4 charge/discharge cycles...which I did!
Over the week I have been using daily and on average I seem to be getting 6.5 hours out of the fully charged battery. Most of this will be with either wireless turned on or my USB modem plugged in. So far, so good as it is performing as expected.
The battery is substantial and is of excellent build quality. In fact they have even added some rubber 'bungs' to the base of the battery since the original development photos (see previous post) to make sure it is a non-slip as it can be. The battery fits into the original battery slot perfectly...frankly I have yet to find anything wrong with it.
The extra angle it adds has really aided in in using the Advent, while the extra airflow under the Netbook can only be beneficial.
So I highly recommend this add-on for anyone looking for a respectable amount of freedom when out and about. For me in university all day in and out of lectures and then when out on the motorcycle, being able to just use the Netbook whenever I want without worrying too much about conserving the battery life has just meant a whole new lease of life!
Head over to Lion Battery to find out more.