Which battery is best for my Discovery 300Tdi?

Q:

Can you tell me what the recommended technical specifications are for my Discovery’s battery, please? It’s a 300Tdi with manual transmission. My battery now is a Brega 70Ah 340A DIN-550A (EN) and I’m not sure this type is the best for this engine.

Peter Erauw, Leuven, Belgium

A:

One battery is not any better than another. If the engine starts easily, that confirms the battery is big enough for the job and is in good enough condition. There’s no need to change it until it fails.

Land Rover specifies part number STC4757 or size 072 as the battery, but it also specifies

a minimum of 570 cold cranking amps (CCA). That means at -18oC, a load of 570A will reduce the battery voltage to 6v in three minutes. Clearly, if you fit a battery that is rated at 800CCA it’ll last longer.

Now, you need to be careful when considering CCA ratings: there’s auto CCA, which is measured at -18oC; and marine CCA, which is carried out at 0oC. Clearly, batteries such as Numax, which are marine-rated, look better on paper than the auto- rated ones.

The golden rule is to fit the biggest battery the tray can accommodate. This will last you longer in terms of years of use than a smaller one.

You’re only buying a lump of lead. Don’t pay over the odds for a fancy name on a label.

Steve Jones