For the unaware, there is a bug for some Sony Ericsson Xperia phones—namely the Xperia Neo and the Xperia Arc—which causes the battery gauge to misread the charge as 0%. Though there is no inherent danger, the bug is still annoying. The bug primarily appears when users downgrade from 2.3.4 to 2.3.2. XDA Senior Member Bazoocaze has posted a workaround for the Neo and Arc to make the 0% bug a thing of the past.
FuelGaugeApp fixes the 0% bug and gives users accurate battery monitoring. Using it is very simple—just install it like you would any other 3rd party apk. The patch has also been integrated into several kernels, some of which are ICS friendly. Despite the ease of use, the method itself is a little convoluted and it’s very highly recommended that anyone who attempts this read the detailed FAQ featured in the Xperia Arc thread.