When it comes to choosing the best battery for your motorcycle it’s not as simple as you might think; from wet lead-acid to AGM and lithium, they all have their benefits and pit-falls. And how should you look after them?

Here are two really useful numbers to look out for. The first is Ah (amp hours), which tells you how many hours a battery will last when something is drawing 1A from it. So a 10Ah battery can supply 1 Amp for 10 hours or 2A for 5 hours. Or 5A for 2 hours and so on; basically it shows you the capacity of the battery.

The higher Ah number, the longer a battery will last.

The other handy number is the Cold Cranking Amps (CCA). You need plenty of power to start an engine – especially a big V-twin – and CCA reveals the number of amps the battery can supply at a temperature of -18°C for 30 seconds without dropping below 7.2 volts. The bigger the engine, the more CCA you need

Did you know… the symbol for amps is always a capital ‘A’ as it’s named after André-Marie Ampère. The same goes for volts thanks to Alessandro Volta

What’s the best lead-acid motorcycle battery?

Lead acid batteries have been around since the middle of the 19th century and all work the same way

A normal 12V lead-acid motorcycle battery is made up of a plastic case containing six ‘cells’. Each cell is made up of a set of lead ‘plates’ – lead for the negative plate and lead-oxide for the positive plate – which are immersed in a sulphuric acid and water solution called ‘electrolyte’. The biggest difference between different lead acid batteries is how that sulphuric acid is stored in the battery.

In a standard ‘wet cell’ battery it’s in liquid form, essentially sloshing around inside. When charging, the chemical reaction generates some hydrogen and oxygen from the chemical components of water (H²O) in the electrolyte, which escapes the battery. That’s why you need to top up with distilled water on occasion.