Getting the spec right: size, terminals and cranking amps
Beyond chemistry, three physical details decide whether a battery fits and performs. First, the case size, quoted as a DIN code (European cars, e.g. DIN 66 or LN3) or a JIS code (Japanese and Korean cars, e.g. 80D26L). The tray, the hold-down clamp and the bonnet clearance are all built around that code, and a battery one size up that cannot be clamped down properly is a hazard, not an upgrade. Second, terminal layout: the L in 80D26L means the positive post sits on the left, and the leads on most cars will not stretch to the wrong side. Third, terminal type: Japanese thin posts and European standard posts are different diameters, and a clamp forced onto the wrong post never makes reliable contact.
The fastest way to get an accurate quote is a photograph of the existing battery's label plus your car's model and year. That single photo tells a vendor the size code, terminal layout, chemistry and rating in one shot, and eliminates the on-site surprise where the van arrives carrying the wrong unit.