Find your battery

Four things decide whether a battery fits. Get these right and the rest is budget.

1. Ah — the capacity

Vehicles: use the Ah your vehicle came with. It is printed on the label of the battery you are replacing, and in the owner's manual. Inverters: use the Ah stated in the inverter's manual. Higher is safe and gives longer backup; lower shortens both the backup and the battery's life.

2. CCA — the cranking punch

Vehicles only. Cold cranking amps is the current available to turn a cold engine over. Never go below what your vehicle came with, whatever the Ah says — a battery with plenty of capacity and not enough CCA will crank slowly on a cold morning and fail early doing it.

3. Terminal side — the one people get wrong

Batteries of identical size come in left- and right-hand terminal layouts. Fit the wrong one and the cables physically will not reach. Stand in front of the battery as it sits in the car and note which side the positive (+, usually red) post is on. Model codes tell you too: an L or R suffix — 40B20L against 40B20R — is exactly this.

4. Physical size

Length × width × height, and whether the clamp at the base still holds it. Height matters most on inverter batteries: a tall tubular cell will not go into a slim trolley.

Would rather we did it?

Send us the make, model, variant and year — or the registration number, which settles the variant on its own — and we will come back with the exact battery, both prices and the warranty. If the label on your old battery is still readable, a photo of it is the fastest route of all.