Well my Hyundai van will be 8 years old in March and it is still on its original battery (A South Korean battery called a "SOLITE") and works fine - watch it fail instantly now I've said that.
So - is it just an extremely good battery or does my van have a very good charging system - or what?
Any battery buffs know the answer? For context Mrs Gold's car - a Suzuki 2.0 diesel - which is a few months newer than my van is three years into its second battery.
I'll take the bait!
I don't think there is a definitive answer. The next Suzuki down the production line after yours most probably still has its original battery if its still around.
In general, modern starter batteries don't have much work to do. They have to deliver a high amperage of current for a few seconds to start the engine but that equates to a little more than what one Shurflo pump would draw in an hour. Once started the alternator will deliver all the power the vehicle needs at idle; the heated rear screen, blower motor, electric heated seats etc. and still put back that little bit of power taken from the battery.
In effect that starter battery should be near on fully charged most of the time. A fully charged battery will last much longer than a battery that is discharged regularly. We all know this with our leisure batteries.
In the old days batteries didn't last that long and were forever going flat. (The first 15 cars I/we owned were all late 50's to mid 80's cars and they all had generators. The first 2 cars I owned were 6 volt and they were worse that the 12 volt vehicles with generators. The first brand new car we bought was a 1984 Mitsubishi Tredia and was the first car with an alternator we owned.)
A car with a generator relied on the battery to supply the extra demand required of the electric system.
We didn't have all the electrical luxuries of modern vehicles such as heated rear windscreens and heated seats in those days. A car radio was a luxury and mostly wasn't worth having as the reception was so bad.
Headlights were a major draw on the battery back then as the generator wouldn't supply enough charge on idle to meet their power demands. So flat starter batteries were an everyday thing in those days, especially in the longer winter nights and cars at idle in traffic congestion and at traffic lights with headlights on.
In South Africa we also had a restriction with regard to lead use in batteries. The manufacturers could only use recycled lead or a % of recycled lead in battery manufacture, or that's what we were told. (We couldn't buy a new battery without having the old battery on the counter.)
In 1988 I purchased a brand new Ford Sierra. Exide batteries lasted less than a year with that car and Exide was the battery to buy back then as it was the best. When I bought the car across to the UK in 1993 the replacement battery lasted until I scrapped the car.
My 04 plate Citroen Relay had to have a new battery 4 years ago. It was the original battery. The local parts shop supplied a Lion battery which didn't last the warranty period.
Who knows how batteries are going to last in vehicles with regenerative braking. The very fact that the alternator will only charge the battery to 80% goes against the rule for battery longevity in batteries as we know it. (The remaining 20% is left for charging on deceleration and braking modes.) Will the higher charging voltages reduce sulphation?
There were numerous issues with battery failure in the early days of calcium batteries in vehicles with regenerative braking. These days there are very few complaints with this new battery technology.
Stop start is another unknown. Although its been out for a while most people turn it off. If they can tolerate it at trafic lights they can't tolerate it when parallel parking I've been told.