Battery from Splash empties

Moin moin together, the 2009 splash of my wife annoys us a little. Over a period of roughly 3 months the battery empties itself. We have already installed a new Varta, rest current measurement in the workshop did not yield any result. Last year in February the Varta came in, roughly from the end of autumn the splash could not start again for the first time. Charged up, again on Christmas and now he stood still again yesterday. Are there known problems? My neighbour said he tipt sta rk on the Lima controller, is it still unique at all? But I also have to mention that she only drives 2 km to work every day…. Shouldn’t that be enough to charge the battery? Thank you in advance, thank you Mirko