Understanding State of Health (SoH)
State of Health (SoH) is a measurement that indicates the current condition of your EV battery compared to its original capacity when new. It's expressed as a percentage, where 100% represents a brand-new battery.
What Do Different SoH Levels Mean?
Excellent
Near-new condition. Expected for vehicles under 2 years old or with less than 30,000 km.
Good
Normal degradation for a well-maintained EV. Most vehicles reach this range after 3-5 years.
Fair
Noticeable range reduction. May be approaching warranty threshold for some manufacturers.
Poor
Significant capacity loss. May qualify for warranty replacement depending on manufacturer terms.
What Causes Battery Degradation
All lithium-ion batteries degrade over time. Understanding the factors that accelerate degradation can help you maximize your battery's lifespan.
Calendar Aging
Batteries degrade simply with the passage of time, regardless of use. This accounts for about 1-2% capacity loss per year.
Cycle Aging
Each charge-discharge cycle causes minor wear. Fast charging and deep discharges accelerate this process.
Temperature Stress
Extreme heat or cold accelerates chemical degradation. Batteries prefer moderate temperatures (15-25°C / 59-77°F).
State of Charge
Keeping the battery at very high (100%) or very low (<10%) charge levels for extended periods increases stress.
Charging Best Practices
The 20-80 Rule
For daily driving, keep your battery between 20% and 80% charge. This "sweet spot" minimizes stress on the battery cells and can significantly extend battery life.
Charging Tips for Maximum Battery Life
- 1Use Level 2 charging when possible
Home charging at 240V is gentler on the battery than DC fast charging. Reserve fast charging for road trips.
- 2Precondition before fast charging
Use your EV's preconditioning feature to warm the battery before DC fast charging, especially in cold weather.
- 3Avoid charging to 100% daily
Only charge to 100% when you need the full range. Set your daily charge limit to 80% in your vehicle's settings.
- 4Don't let the battery sit at extremes
If storing your EV for extended periods, keep the battery around 50% charge rather than full or empty.
Temperature & Battery Health
Temperature is one of the most significant factors affecting battery health. Modern EVs have thermal management systems, but you can help them work more effectively.
🔥 Hot Weather Tips
- • Park in shade or use a garage when possible
- • Avoid fast charging when the battery is already hot
- • Use scheduled charging during cooler nighttime hours
- • Precondition the cabin while still plugged in
❄️ Cold Weather Tips
- • Keep the vehicle plugged in when parked in cold
- • Use battery preconditioning before driving
- • Expect reduced range in extreme cold (temporary)
- • Park in a garage if available
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