On my 2021 mk4 I regularly used a voltmeter that plugs into the 'cigarette lighter' socket. This quite often showed resting voltage in the 11's (rising to 14.7 volts when the car is powered up) if the car hadnt been used for more than a few days . Even though the car might previously have done a long trip.
This was a bit disconcerting as on line information suggests that even voltages in the low 12's indicates a low state of charge, and under 12v a seriously low one.
This prompted me to buy a small 'power bank' jump starter which i carry in the car for emergencies. But in 3 years of ownership the small battery never failed to power up the car , even though I had never put it on a trickle charge using a CTEK etc.
Must admit with my 2024 car I have only inserted the voltmeter a couple of times, when the car was new and recently used, so no surprise the resting charge was over 12 volts. I decided that leaving the voltmeter plugged in tends to act as a 'worry meter' . So I dont know if Panasonic battery performs better when unused for long periods than the brand Honda fitted in 2021. I would rather just trust it to continue working for as long as possible. . I have emergency back up.
If repeated need for emergency back up indicates the battery is on its last legs,or I need to regularly externally trickle charge I will rethink my strategy. Not sure ,as has been suggested ,that I would ask a Honda dealership to check battery condition at maybe 3 years as a precaution. . Too much of a temptation for them persuade you to buy their over priced battery just to 'be on the safe side'. blah blah.
