After replacing a lot of times the battery to the kitchen clock the final solution is applied. A small switching power supply from eBay with 1 MHz switching clock adjusted to 1.4-1.5 V powers the kitchen clock. The same power supply with a 13.8 V Lead Acid battery powers the MP3 & FM radio protecting them from power fails. The power will arrive with a thin enameled wire that will be painted over the wall hiding it. At the clock will be enough spare wire so I can eject the clock from the wall without cutting the wire if needed.