Does an the alternator only keeps a battery to its existing charge level?

I read a recent reply of yours to a Honda CR-V owner whose stop/start isn't working, where you advised a new battery. We recently bought a 2013 CR-V with a 12 month warranty from a main dealer and the stop/start ceased working after about a week. It didn't restart for four months - even after a four hour drive. The local Honda service agent checked the car (the main dealer is 60 miles away) and said that the battery was 75 per cent charged and 'good', but suggested to the dealer that replacing the battery would be sensible. The dealer doesn't want to do this. When I asked the local agent why the battery wasn't fully charged he said that the alternator only keeps a battery to its existing charge level, which I frankly don't believe. I thought the whole point of an alternator was that it charged a battery to, but not over, its capacity.

Asked on 5 June 2017 by Simon Tattersall

Answered by Honest John
Depends entirely on your usage of the car. If you run it 100 miles plus every day, the battery remains fully charged and retains its capacity to hold a full charge of 13.5 volts and can last 10 years. If you run it short distances then the battery does not fully recharge and gradually loses its capacity to hold a full charge.
Similar questions
Recently, the fan belt, tensioner and battery light came on in my 2004 Ford Mondeo. I had belt and tensioner replaced, but battery light still. I checked the battery voltage for charging, with the engine...
Recently, the battery light on my Volkswagen Touran 2.0 TDI comes on above 3000 revs but as soon as I drop below it goes off again. There is also a whirring noise when starting the car. Turbo boost is...
I am being told by Smart that the stop-start on my Smart Fourtwo will not work when the external temperature is outside of a suitable range. Today the extenal temperature is 9C, and it still won't operate....
Related models
1.6 i-DTEC is punchy and efficient, massive boot and a spacious cabin for five adults, superb build quality edges the CR-V into premium territory.

Value my car