Advice · updated 2026-10-03
CCA and Ah ratings explained
CCA is the cold starting current. Ah is how much charge the battery holds. Both should match what the car was specified with, along with the case and whether it's flooded, EFB or AGM.
Ah is how much the battery can hold
Amp-hours describe capacity. A higher Ah figure means the battery can supply a modest current for longer, which matters for stop-start cycling, short trips and cars that sit. It is not a score you raise for its own sake if the case will not fit the tray.
Match the Ah the car was specified with, or the figure on the old label when that label is the correct type. A bigger Ah that does not fit under the hold-down is not an upgrade. It is a battery that will not clamp.
CCA is the starting punch
Cold cranking amps, often printed as CCA or as an EN figure, describe the current available to turn the engine from cold. Two batteries can share an Ah number and differ on CCA. The lower CCA unit may crank poorly on a cold morning even though the capacity looks the same on the sticker.
Do not drop CCA to change the quote. The callback matches the figure the car needs. Standards differ in how they are printed, so read the number next to the standard name on the label rather than comparing two bare numbers from different test methods as if they were identical.
Type still outranks both numbers
A flooded battery with the right Ah and CCA is still wrong for an AGM car. An AGM must not be downgraded. An EFB may be upgraded to AGM. Get the technology right, then the size, then Ah and CCA.
Photograph the label and type your mobile number. We call you back. The fitter comes to the car in London, Birmingham or Manchester and fits the agreed spec. Resting voltage around 12.6V is a health check, not a substitute for the CCA figure on the label.
Questions before you send a quote
Is a higher Ah always better?
Only if it fits and the car can use it. The hold-down and the specified battery come first.
Is CCA the same as Ah?
No. Ah is capacity. CCA is starting current. Match both.
Can you match this at the car?
Yes. Send the label details with your mobile number and we call you back.
A worked example
A label shows 60Ah and 640A EN. A different 60Ah battery marked with a much lower EN current is not the same starting battery, even if the case looks alike. The quote uses 60Ah and 640A EN, plus EFB or AGM as the label states. The fitter checks that against the car before fitting.