8 min readPublished 10 February 2025
Choosing the right car battery seems complicated, but following a simple step-by-step process makes it straightforward. This beginner-friendly guide walks you through checking battery type, size codes, Start/Stop requirements, and selecting the right battery for your vehicle and driving habits.
Use our Battery Fitment Tool to simplify the process, or follow these steps to identify your requirements manually and make an informed purchase decision.
Quick Answer
Choose the right battery in 5 steps: (1) Check battery type (AGM/EFB/standard), (2) Check size code (096, 110, etc.), (3) Check Start/Stop requirements, (4) Consider driving pattern and climate, (5) Choose between budget, mid-range, and premium. Always match or exceed original specifications.
Common causes
- -Not checking original battery specifications before purchasing
- -Choosing wrong battery technology for Start/Stop vehicles
- -Focusing only on price without considering quality and warranty
Typical fixes
- -Use Battery Fitment Tool to identify exact requirements
- -Check existing battery label or vehicle handbook for specifications
- -Match battery technology (AGM/EFB/standard) to vehicle requirements
- -Choose premium brands for Start/Stop vehicles - they last longer
Battery Selection Quick Steps
Need to replace car battery
Likely cause: Follow 5-step selection process
Next step: Check battery type, size code, Start/Stop, then choose appropriate battery
Vehicle has Start/Stop system
Likely cause: Requires AGM or EFB battery (never standard)
Next step: Check existing battery label for technology type, match or upgrade
Not sure what battery to choose
Likely cause: Use Battery Fitment Tool or check vehicle handbook
Next step: Enter vehicle details in fitment tool or consult handbook specifications
Commercial van or high electrical load
Likely cause: Needs AGM battery with higher capacity
Next step: Choose premium AGM with 75-80Ah capacity for reliability
Step 1: Check Battery Type (AGM/EFB/Standard)
The first step is identifying which battery technology your vehicle uses. Check the existing battery label - it will clearly state 'AGM', 'EFB', or may not mention either (indicating standard flooded).
This is critical because Start/Stop vehicles require AGM or EFB batteries. Fitting a standard battery will disable Start/Stop and cause premature failure.
- Look at existing battery label for technology type
- AGM or Absorbent Glass Mat = AGM battery required
- EFB or Enhanced Flooded Battery = EFB battery required
- No mention of AGM/EFB = standard flooded battery (conventional vehicles only)
- If battery label is missing, check vehicle handbook or use Battery Fitment Tool
Step 2: Check Battery Size Code
Battery size codes (like 096, 110, 027) indicate physical dimensions and are standardized across manufacturers. The size code ensures the battery fits your vehicle's battery tray.
Common UK size codes include 096 (most popular), 110, 027, and others. Always match the size code to ensure proper fitment.
- Check existing battery label for size code (usually prominent number like '096')
- Size code indicates physical dimensions (length × width × height)
- Most common UK size: 096 (278mm × 175mm × 190mm)
- If unsure, measure existing battery or check vehicle handbook
- Wrong size code means battery won't fit physically
Step 3: Check Start/Stop Requirements
If your vehicle has Start/Stop technology, it requires AGM or EFB batteries - never standard flooded. Check for a Start/Stop button on your dashboard or consult your vehicle handbook.
Start/Stop systems automatically stop the engine when stationary and restart it when you release the brake. This technology places unique demands on batteries that standard types cannot meet.
- Look for Start/Stop button on dashboard (usually marked 'A' with circular arrow)
- If Start/Stop present, you need AGM or EFB battery (check existing battery for which type)
- Advanced Start/Stop with energy recovery requires AGM (not EFB)
- Never downgrade from AGM to standard - it will disable Start/Stop and fail quickly
- If unsure, check vehicle handbook or use Battery Fitment Tool
See also: Why Start/Stop needs AGM/EFB
Step 4: Consider Driving Pattern and Climate
Your driving habits and local climate affect battery requirements. Short-trip drivers, commercial users, and those in extreme climates may benefit from higher-capacity batteries or premium brands.
Short Journey Considerations
If you primarily drive short distances (under 10 miles), your battery rarely reaches full charge. Consider higher-capacity batteries or AGM technology even if Start/Stop isn't present, as AGM batteries have better charge acceptance.
- Short journeys prevent full battery recharge
- Higher capacity (Ah) provides more reserve between charges
- AGM batteries charge faster than standard/EFB
- Consider using smart charger weekly for short-trip vehicles
Cold Climate Considerations
UK winters demand batteries with strong Cold Cranking Amps (CCA) ratings. Premium brands typically offer better cold weather performance. Ensure your battery meets or exceeds the original CCA specification.
- Cold reduces battery capacity (CCA drops in freezing temperatures)
- Choose batteries with CCA at or above original specification
- Premium brands (Varta, Bosch) offer better cold weather performance
- Higher CCA important for diesel engines in cold weather
Commercial or High Load Use
Commercial vans and vehicles with high electrical loads (accessories, inverters) need premium AGM batteries with higher capacity. Budget batteries fail quickly under these conditions.
- Commercial use requires premium AGM batteries
- Choose higher capacity (75-80Ah) for vehicles with accessories
- Premium brands essential for reliability and warranty
- Plan for more frequent replacement (3-4 years vs 5-6 years)
Mid-Range Batteries (Yuasa, Exide)
Mid-range batteries offer good value with reliable performance and decent warranties. Suitable for most passenger vehicles.
- Cost: £100-£150 for AGM, £80-£120 for EFB/standard
- Warranty: 3-4 years typical
- Best for: Standard passenger vehicles, value-conscious buyers
- Good balance of price and quality
Budget Batteries (Lion, Other Brands)
Budget batteries cost less but have shorter warranties and may not perform as well in demanding conditions. Not recommended for Start/Stop vehicles or commercial use.
- Cost: £70-£120 for AGM, £50-£90 for standard
- Warranty: 2-3 years typical
- Best for: Low-mileage vehicles, tight budgets (not Start/Stop)
- May need replacement sooner, lower quality
Final Specification Checklist
Before purchasing, verify all specifications match your requirements. Use this checklist to ensure you're buying the right battery.
- ✓ Battery technology matches (AGM/EFB/standard)
- ✓ Size code matches (096, 110, etc.)
- ✓ Capacity (Ah) matches or exceeds original
- ✓ CCA rating matches or exceeds original
- ✓ Physical dimensions fit battery tray
- ✓ Terminal orientation correct (positive/negative position)
- ✓ Warranty length acceptable for your needs
- ✓ Brand reputation suitable for your vehicle type
Using the Battery Fitment Tool
Our Battery Fitment Tool simplifies the selection process by identifying exact battery requirements based on your vehicle details. Enter your registration number or select your vehicle make/model, and the tool recommends compatible batteries.
- Enter vehicle registration number for automatic lookup
- Or select vehicle make, model, and year manually
- Tool identifies battery type, size code, capacity, and CCA requirements
- Shows compatible batteries with current prices
- Eliminates guesswork and ensures correct selection
See also: Use the Battery Fitment Tool now
Common Mistakes to Avoid
Avoiding these common mistakes saves money and prevents problems.
- Don't downgrade from AGM to standard in Start/Stop vehicles
- Don't choose wrong size code - battery won't fit
- Don't focus only on price - quality matters for Start/Stop vehicles
- Don't skip BMS registration after installation in Start/Stop vehicles
- Don't assume all batteries are the same - technology matters
After Purchase: Installation and Registration
After purchasing the correct battery, proper installation ensures optimal performance and longevity.
- Have battery installed by professional if unsure (many garages include this)
- For Start/Stop vehicles: Register battery with BMS using diagnostic tool
- Ensure terminals are clean and tight
- Check alternator output after installation (13.7-14.7V is normal)
- Keep receipt for warranty purposes
See also: Why BMS registration matters
AI-Friendly Summary
- Follow 5 steps: Check battery type (AGM/EFB/standard), check size code, check Start/Stop requirements, consider driving pattern and climate, choose budget/mid-range/premium.
- Always match battery technology to vehicle requirements - Start/Stop vehicles need AGM or EFB, never standard flooded.
- Use the Battery Fitment Tool to simplify selection - enter vehicle details and get exact battery recommendations.
- Match or exceed original specifications (capacity, CCA) but ensure physical dimensions fit.
- Choose premium brands for Start/Stop vehicles and commercial use - they offer better warranties and longer lifespans.
Frequently Asked Questions
Do I need to code the battery after replacement?
Yes, if your vehicle has Start/Stop technology, you should register the new battery with the Battery Management System (BMS). This tells the vehicle the new battery's capacity and technology type, allowing correct charging and Start/Stop operation. Many garages include this service, or you can use diagnostic tools like OBDeleven if your vehicle supports them.
Can I use a higher capacity battery than the original?
Usually yes, as long as it physically fits and matches the technology type (AGM/EFB/standard). Higher capacity provides more reserve but ensure dimensions fit your battery tray. For vehicles with Battery Management Systems, you may need to update the BMS to recognize the new capacity.
What if I can't find the original battery specifications?
Use our Battery Fitment Tool with your vehicle registration number - it will identify exact requirements. Alternatively, check your vehicle handbook, consult a dealer, or measure your existing battery (if still fitted) to identify size code and check the label for technology type.
How do I know if my car has Start/Stop?
Look for a Start/Stop button on your dashboard (usually marked with 'A' and circular arrow icon). You may also see it activate automatically - the engine stops when you come to a halt and restarts when you release the brake. Check your vehicle handbook if unsure.
Is it worth paying more for a premium battery?
For Start/Stop vehicles and commercial use, yes - premium batteries offer longer lifespans (5-7 years vs 3-4 years), better warranties (4-5 years vs 2-3 years), and superior performance. The higher initial cost is offset by longer service life and fewer replacements. For standard vehicles with low mileage, mid-range batteries may offer better value.
What's the most important thing when choosing a battery?
Matching the battery technology (AGM/EFB/standard) to your vehicle requirements is most critical. Getting this wrong disables Start/Stop systems and causes premature failure. After technology, match size code for physical fitment, then capacity and CCA to meet or exceed original specifications.
