I normally get about 7 years from a battery, top ups from a charger make a massive difference to battery life. Get them load tested at each service interval and they will never die unexpectedly
Top ups with a smart charger appear to be effective in prolonging battery life.
Modern cars have alternators that are controlled by the Engine computer.
In the 'old' days; alternators charged at around 14.5 volts.. When the battery was fully charged.. a regulator stopped the charging.
Now... The battery charges at around 14.5v for a short period after starting the car to 'top up' the battery... then reduces charge rate to something a lot less (have forgotten exactly)... Which doesn't charge the battery properly, but keeps the car's electronics alive.
All done to reduce fuel consumption and emissions ........ at the expense of your battery due to its shortened life.
And stop/start technology.. again to reduce consumption and emissions...... makes it worse...these cars have a special battery to handle these repeated starts and of course this battery is dearer. And could imagine the starter motors wouldn't last as long as well
You will often find it's the dead of winter that finally takes them out!
Yep!. Cold weather reduces battery capacity. Usually the straw that breaks the camel's back