Battery CCA Calculator
Estimate Cold Cranking Amps (CCA) from Amp Hours (Ah)
Battery CCA Calculator
Estimate Cold Cranking Amps
Results:
Cold Cranking Amps (CCA): 0.00
How to Use the Battery CCA Calculator
Input Amp Hours (Ah)
- Enter the Amp Hour (Ah) rating of your battery.
- This value represents the battery's capacity.
Input Conversion Factor
- Enter a conversion factor, typically between 7 and 10.
- A common value is 7.5, but it varies by battery type.
Get Estimated CCA
- Click "Calculate" to get the estimated Cold Cranking Amps (CCA).
- The result provides an estimate of the battery's cold-starting power.
How to Calculate Battery CCA
Use these quick steps to translate the labeled amp-hour capacity into realistic cranking power for cold-start scenarios.
Step 1: Gather Battery Specs
Confirm the rated amp-hours, nominal voltage, and chemistry (flooded, AGM, gel, or lithium) from the data plate or spec sheet.
- Starter batteries list CCA directly; deep-cycle units often list Ah only.
- Document the expected minimum ambient temperature for cranking.
Step 2: Set the Temperature Target
CCA is defined at 0°F (-18°C). If you are sizing for milder climates you can bias the factor toward the low end of the range.
- Use factors near 7 for temperate regions and balanced deep-cycle use.
- Move toward 9-10 when frequent sub-zero starts are expected.
Step 3: Pick the Conversion Factor
Match the factor to chemistry and build.
- Flooded/AGM starter batteries: 8.0 - 9.5
- Dual-purpose deep cycles: 7.0 - 8.0
- Lithium drop-ins (with BMS limits): 6.5 - 7.5
Step 4: Run the Formula
Multiply amp-hours by the factor.
CCA = Ah × Conversion Factor
Example: 85 Ah × 8.2 ≈ 697 CCA.
Step 5: Cross-Check with Data Sheets
Compare your calculated result with published CCA or MCA values from the manufacturer to ensure you are within ±10%.
- If the delta is higher, adjust the factor to match real lab tests.
Step 6: Add Design Margin
Account for aging, sulfation, and voltage drop in long cables by adding 10-20% to the required CCA.
- Sizing margin ensures reliable starts after a few winters.
- Parallel batteries should each meet the minimum CCA requirement.
Battery CCA Chart
Estimates are based on CCA = Ah × Factor. Adjust the factor to match your chemistry and temperature range.
| Battery Setup | Amp Hours (Ah) | Conversion Factor | Estimated CCA* | Typical Application |
|---|---|---|---|---|
| Group 24 flooded starter | 50 Ah | 8.0 | 400 CCA | Compact passenger cars above freezing |
| Dual-purpose 60 Ah AGM | 60 Ah | 8.5 | 510 CCA | Marine/ RV house-start combos |
| Deep-cycle 75 Ah gel | 75 Ah | 7.2 | 540 CCA | Electric winches & light utility vehicles |
| Heavy-duty 100 Ah AGM | 100 Ah | 9.0 | 900 CCA | Diesel pickups and standby gensets |
| Lithium 100 Ah drop-in | 100 Ah | 7.0 | 700 CCA | Cold-start assist with BMS current limits |
| Commercial 120 Ah flooded | 120 Ah | 9.5 | 1,140 CCA | Medium trucks and equipment fleets |
*Always verify with the manufacturer's published CCA rating before committing to a design or replacement plan.
Battery CCA FAQs
Quick answers to the most common CCA and amp-hour conversion questions.
What is 100Ah in CCA?
Amp-hours multiplied by a realistic conversion factor give you an estimate. A 100 Ah AGM battery with a factor of 7.5 to 9.0 lands between 750 CCA and 900 CCA. Use the higher end if the battery is purpose-built for cranking and you regularly see sub-freezing starts.
How many CCA is a 60Ah battery?
Most 60 Ah dual-purpose batteries use factors between 7.5 and 8.5. That produces 60 × 7.5 ≈ 450 CCA on the conservative end and 60 × 8.5 ≈ 510 CCA when optimized for cranking. If you need more starter current, step up to a higher Ah or an AGM starter-specific model.
How do you calculate the CCA of a battery?
Use the empirical relation CCA = Ah × Conversion Factor. Pick the factor based on chemistry, plate surface area, and target temperature, then multiply by the rated amp-hours. Finally, compare with the spec sheet to ensure your assumption is within about ±10%.
How many amp hours is a 550 CCA battery?
Rearrange the formula to Ah = CCA ÷ Factor. With a typical factor of 7.5, Ah ≈ 550 ÷ 7.5 ≈ 73 Ah. A more aggressive factor of 8.5 indicates roughly 65 Ah. Check the manufacturer's reserve capacity or 20-hour rating for the precise value.
Can I run a 3000 watt inverter off of a car battery?
A single automotive starting battery is not ideal. A 3,000 W inverter at 12 V can draw 250+ amps continuously, far exceeding what a typical 650 CCA (≈70 Ah) battery can supply without severe voltage sag. Use a dedicated deep-cycle bank sized for the load (multiple batteries or a large lithium pack) and verify the inverter surge and cable sizing.
How many CCA is a 120Ah battery?
Multiply 120 Ah by the factor suited to your chemistry. Flooded commercial batteries with a factor of 9.0-9.5 yield 1,080-1,140 CCA. High-performance AGM units can exceed 1,200 CCA when optimized for cranking.
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