Icom IC-7300 owners are experiencing real-time clock battery failure issues. More information here: https://forums.qrz.com/index.php?posts/4977810/ The IC-7610 Basic manual <http://www.icom.co.jp/world/support/download/manual/pdf/IC-7610_ENG_Basic_2a.pdf> states on page 8-9: "NOTE: The backup battery for the internal clock The IC-7610 has a rechargeable Lithium battery to backup the internal clock. If you connect the transceiver to a power source, the battery is charged and it keeps the correct clock setting. However, if you do not connect the transceiver to a power source for a long period of time, the battery will discharge. In that case, the transceiver resets the internal clock. If you do not use the transceiver for a long period of time, we recommend that you connect the transceiver to a power source at least once a month. The charging period is two days whether the transceiver’s power is ON or OFF." I've not been able to find an IC-7610 Service manual on-line, so I am unable to determine if the IC-7610 RTC battery is the same as the one in the IC-7300. But, because the notice above is similar to the one that Icom recently added to the IC-7300 manual, I suspect the batteries are similar. This subject may have been discussed in the past, but all I could find was this thread: https://groups.io/g/ic-7610/topic/27749255#11703 Are IC-7610 owners experiencing RTC battery failures?