Using Ubuntu 12.04 over ASUS K55V I wonder if it is possible to turn off battery charging and run the system over direct supply??? This function is available with dell laptops in Microsoft Windows. Is this function available within Ubuntu???
This is a hardware option and not software. That said the answer is almost 100% no. Even the "dell" laptops don't really turn off charging. At a hardware level LiON battery need a very small charge 100% of the time or they will discharge (or worse, burn out). Most charging circuitry will handle this by discharging and recharging the battery in a tiny increment.
Even Dell laptops would be subject to this requirement if there running LiON batteries.