When you need a new car battery, battery group size, a standardized code that tells you the physical dimensions, terminal placement, and mounting style of a battery. Also known as battery size group, it’s the first thing you should check before buying a replacement. It’s not just about fitting the battery into the tray—it’s about making sure the terminals line up with your car’s cables and that the hold-down clamp actually secures it. A battery that’s too big won’t fit. One that’s too small might rattle loose. And if the terminals are on the wrong side, you’ll be stuck with cables that won’t reach.
Group sizes like 24F, 35, 48, and 95R aren’t random. They’re set by the Battery Council International (BCI) so manufacturers and drivers know what works. For example, a battery terminal location, where the positive and negative posts are positioned on top or side of the battery matters because UK cars often use side terminals for tighter engine bays, while older models stick with top posts. If you swap a top-post battery for a side-post one without checking, you’ll need adapters—or worse, damage your cables trying to force a connection.
Then there’s battery cold cranking amps, the measure of how much power a battery can deliver at 0°F (-18°C) for 30 seconds while maintaining voltage. Cold weather makes engines harder to start, so a battery with low CCA might crank slowly or not at all in winter—even if it’s the right group size. Your car’s manual lists the minimum CCA needed. Going lower risks failure. Going much higher won’t hurt, but it might cost more than you need.
Don’t assume all batteries with the same group size are equal. Some are heavier, have thicker plates, or use different internal tech. A budget battery might fit but die in 18 months. A quality one lasts 5+ years. And while group size tells you the shape, it doesn’t tell you if the battery can handle your car’s electrical load—especially if you’ve added aftermarket sound systems, LED lights, or off-road gear.
You’ll find plenty of posts below that cover real-world battery issues: why your car won’t start even with a new battery, how to test if your battery is truly dead, and what happens when you install the wrong group size. Some drivers swap batteries without checking fitment and end up with melted terminals or damaged starter motors. Others buy the right size but ignore CCA and struggle in winter. We’ve seen it all.
Whether you drive a Fiat 500, Alfa Romeo Giulia, or a Maserati Quattroporte, getting the battery group size right saves you time, money, and stress. The posts here give you the facts—not guesswork. No fluff. Just what works on the road, in the garage, and in the UK’s unpredictable weather.
