A battery label can show several large numbers, but they describe different things. Understanding the labels helps you compare suitable products instead of choosing whichever number looks highest.
Cold cranking amps: a starting rating
CCA describes starting-current performance under a specified cold-temperature test. Use the minimum requirement provided for your vehicle or engine and compare products using the same rating standard. CCA does not tell you how long a battery can run an RV's lights or a mobility scooter.
Amp-hours: capacity under stated conditions
Amp-hours, usually written Ah, describe capacity measured at a stated discharge rate. Check the rate alongside the number. A 20-hour capacity rating should not be treated as identical to a rating measured under different conditions, and actual runtime depends on the load and operating conditions.
Reserve capacity: a time-based rating
Reserve capacity, or RC, is expressed in minutes under a defined test load and endpoint. It offers another way to compare suitable batteries under consistent test conditions. It is not a promise that your particular equipment will run for that exact number of minutes.
Use the rating that matches the application
For a starting battery, check the engine's required starting specification. For a deep cycle application, check capacity, permitted use, and charging compatibility. Some products publish multiple ratings, but that does not make every starting battery suitable for repeated deep cycling.
Keep the rest of the specification beside the numbers
- Voltage and required chemistry.
- Case size, terminal layout, and hold-down.
- Intended application and permitted connections.
- Charger compatibility and care instructions.
- Warranty terms for the actual use.
Consider a shopper comparing two batteries with different Ah ratings. The larger figure is not useful if that battery is too tall for the compartment or the equipment requires a different chemistry. Check compatibility first, then compare performance among suitable products.
Bring the label to the shopping decision
Take a clear photo of the existing battery label and record the equipment model. Use those details with the manufacturer's specification when browsing DIYBattery. Our product pages provide the listed ratings so you can compare before arranging local delivery.
Ask for help choosing a battery if any of the ratings or application requirements are unclear.
Rating background: Yuasa battery specification guide.
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Related local buying guides
Which number should lead your choice?
| Rating | Unit | Use it for | Do not assume |
|---|---|---|---|
| Cold cranking amps | A | Compare cold-start output among otherwise suitable starting batteries | It describes runtime or deep-cycle life |
| Amp-hours | Ah at a stated rate | Compare capacity among suitable deep-cycle batteries tested on the same basis | It guarantees runtime in your equipment |
| Reserve capacity | Minutes at a defined load | Compare reserve among similarly rated products | It replaces the vehicle's CCA requirement |
For example, Canada Proof G3572 lists 640 CCA and 100 minutes of reserve capacity. Those are two different measurements on one 12V Group 35 flooded starting battery. Confirm the vehicle's complete specification before comparing its CAD price with another product.