Johntheo1 wrote: ↑Fri Nov 05, 2021 2:46 pm
Wouldn't be too worried about the key fob batteries, scrapped a VW Bora after exactly 19 years with the original key fob batteries and one replacement 12V.
BTW, I am quite happy that presently my wife's 2015 Polo is not over charging its battery now since I changed the serial number, presently it is keeping it charged higher than intended so there must be a slight waste of fuel happening, I'm probably more interested in where this is leading to as initially the changing charging profile/level came as a step change and was at the start of that change definitely over charging that battery, so logically the charging system should eventually adapt itself back to these values that caused it to constantly charge at 14.9V.
Key fob batteries, yes, I replaced the batteries in the keys of my bought new 2000 Passat 4Motion at maybe 12 years - why, because these batteries would now be beyond their useful age, same for my wife's bought new 2002 Polo.
With my 2011 Audi S4, I changed the key batteries just before the 10 year point, the open circuit voltage of the old ones, even the mainly unused one was down to just over 3V, I did the same on the 2015 Polo at the 6 year point, and again the batteries were both getting close to or below 3V.
My daughter's May 2019 SEAT Leon Cupra reported "replace key battery" or a similar warning back in the summer time, and its battery in her key was down to just below 3V - replacing the Panasonic original with a Sony(bought in error by me) sorted out that warning - her partner's key has not caused any warnings to get issued yet, though he rarely drives that car - it does not have KESSY, so goodness knows why newer VW Group cars need key batteries replaced sooner than older ones did.