Today at Atelier Kaz - ex-Honda R&D, F1, Indy/CART engineer

Following on from the last blog on the Jump Battery, another battery related topic.

First, as mentioned many times, please keep your battery in good condition.
Otherwise, it could damage your alternator indirectly.

It’s like the question of which one was first, the chicken or the egg?


One day, you found that you had to jump start the car due to weak battery.

Once started, the alternator had to work really hard in order to charge up the weak battery that will never recover the full capacity.
The alternator got really hot resulting in partially damaged rectifier.

You managed to start the engine many times afterwards and kept driving without noticing the damage to the alternator.
Days later, once again the battery was too weak to start the engine.

So, you decided to replace the battery with the new one but the alternator is not perfect that you got the new battery only to be damaged everytime when you drive the car.

Then you noticed that something wrong with the alternator but by that time, your new battery was damaged and will never recover the full capacity.

By the time you sorted the alternator, the damages were done to the new battery and shorten its life.

And you just repeat the above within short cycle like every few years.


It all depends on many factors but with the ordinary lead acid flooded battery, you should be able to keep the same battery for well over 5 – 8 years on our NSX based in UK if looked after properly.

I normally replace this type of battery every 8 years here in UK even if no sign of fatigue when cranking the engine.
Just keep it as emergency spare for other purpose.

In Japan, due to extremely hot summer, difficulty in accessing the power socket outside and fairly low speed limit with low annual mileage, people tends to replace their ordinary battery at much shorter cycle, like less than every 5 years.

UK summer is getting really hot recently so for the first time, I had to replace my battery after 7 years last time.
The cranking speed got bit slower and the voltage dropped just below 10V while cranking.

With classic MX-5, the OEM gel battery can go well over 10 years.
I normally replace it every 10 – 12 years as gel type requires more attention than the AGM.

For some, it may be too complicated and want something simple as a reference.