I have a lot of experience and litterature regarding battery maintenance.It sounds to me that Moedip has come across a neat new product which I will have to check out. There are a couple of things to remember about storing batteries.First of all to reduce the discharge rate, the batteries should be stored in a cool place like on concrete. Secondly in order to accurately check a stored battery's state of charge,you must either wait a couple of days after charging or put a load on the battery to remove the surface charge. You should then read a voltage of 12.6 volts with a digital volt meter. This reading indicates a fully charged battery.
Hope this info helps,
Auto Zentral Ltd.