The 215 year-old part in your car

As sophisticated as modern cars are, they still rely on one part that's positively ancient

HUMAN BEINGS CAN gulp down an espresso to get going, but car engines need cranking from a starter motor. And that in turn needs a huge jolt of electricity from a battery.

Amazingly, some batteries owe their basic design principles to the first voltaic pile created by Alessandro Volta 215 years ago! Of course, the modern battery in your car can be a sophisticated piece of kit. Here's what you need to know about it:

There are three common types of car battery
Carmakers have used a lead-acid kind of battery for decades. Lately, a sealed type (sometimes called a ‘maintenance-free' battery) has become more common. A third, even newer kind sometimes referred to as a ‘gel' battery is appearing in the latest cars.

Maintenance-free batteries are, well, easy to maintain
Lead-acid batteries are cheap and very reliable, but they have to be topped up with distilled water periodically.

‘Maintenance-free' batteries use glass mats (which is why they're called ‘Absorbed Glass Mat' or ‘AGM' batteries) to absorb the sulphuric acid and keep it stable, and don't have to be topped up with electrolyte periodically.

They can also be charged more quickly, and don't expel hydrogen and oxygen gasses, like lead-acid batteries. That makes it less likely you'll find corrosion on the terminals, which saves you from doing the messy job of cleaning them and coating them in grease.

Those characteristics also apply to gel-type batteries, which have a paste-like (instead of fluid) electrolyte inside, making them able to tolerate shocks and vibrations well.

A failing battery is easily spotted
It takes just a quick test with the right equipment to diagnose a battery's health. One other sign is slow-cranking or difficult starting (your car should roar to life smoothly, not wake up the same way you do after a night of hard partying).

Some batteries have a small window on top that lets you see how healthy it's feeling (if you see green, that's good).

You can leave a battery alone, but you can't forget it
The problem with a battery is that you discover that it has gone to the big charging station in the sky only when you're stranded with a car that refuses to wake up.

To prevent this, ideally you should try to drive your car for half an hour at least once a week in order to keep your battery in good health. Modern cars have various electrical needs that slowly drain a battery even when the car is left parked.

A battery is a battery — not!
Modern cars have surprisingly sensitive electrical needs. Non-approved batteries or replacement work by outside workshops may lead to malfunctions such as short circuits.

They could cause interference with electrical functions like lighting, or even safety items like the ABS (Anti-lock Braking System) or ESP (Electronic Stability Program) systems. Some functions, like engine start-stop, require batteries of a specific type or capacity.

The wrong kind of battery may work for a while with your car, but it's unlikely to last long.

An authorised dealer will stock exactly the right kind of battery for your car, and where necessary can perform a re-initialisation of the car's systems with the new battery.

The upshot of the above is that being stranded with a dead battery is an unnecessary and preventable headache, especially since batteries show early signs of failure that can be picked up by an authorised dealer.

For example, every workshop at Cycle & Carriage has approved battery-testers to analyse the condition of your car's battery, to see if it's still in good working condition or needs to be recharged or replaced. Why leave it to chance?

Of course, the best time to see to a battery's needs is before it calls it quits. A car that won't crank up is liable to leave you feeling, well, cranky.