Abstract: A battery assembly comprising a number of batteries in a holder with a first end surface directed to the same side of the battery assembly comprising both a plus pole and a minus pole. The battery assembly comprising an anode plate and a cathode plate covering the battery assembly on the same side as the anode plate with an electrically isolating layer between plates comprising through openings through the formed sandwich structure in connection to each battery and a minus connector connecting the minus pole of each battery to the anode plate and a plus connector connecting the plus pole of each battery to the cathode plate.