EV Battery Health Guide
Everything you need to know about maintaining and understanding your electric vehicle's battery
Why Battery Health Matters
Your EV's battery is its most expensive and important component, often representing 30-40% of the vehicle's total value. Understanding battery health isn't just about range—it's about protecting your investment, maintaining resale value, and ensuring your vehicle performs as expected.
Unlike traditional cars where engine wear happens gradually over hundreds of thousands of kilometers, EV battery degradation is influenced by many factors: how you charge, where you drive, and even where you park. The good news? With proper care and regular monitoring, modern EV batteries can last well beyond their warranty periods.
This guide will help you understand what affects battery health, how to maximise battery life, and when to seek professional assessment.
Understanding Battery Health
Your EV’s battery is its most valuable component. State of Health (SOH) measures the current capacity compared to when new. A healthy battery should retain 85-90% capacity after 5 years. Factors affecting health include charging habits, temperature exposure, and driving patterns.
Normal vs Abnormal Degradation
Expect 2-3% capacity loss per year under normal conditions. Degradation below 80% SOH within warranty period may qualify for replacement. Rapid degradation (>5% annually) indicates potential issues requiring professional assessment.
Optimal Charging Practices
Keep your battery between 20-80% for daily use. Avoid frequent DC fast charging when possible. Charge to 100% only before long trips. Use scheduled charging during cooler nighttime hours to reduce heat stress on the battery.
Temperature Management
Extreme temperatures accelerate battery degradation. Park in shaded areas during summer. In winter, precondition your battery before driving. Modern EVs have thermal management systems, but you can help by avoiding temperature extremes when possible.
Warning Signs
Watch for: significant range loss (>20% reduction), longer charging times, battery warning lights, unusual battery temperature, or inconsistent performance. These signs warrant a professional health check.
Warranty Coverage
Most EV batteries have 8-year/160,000km warranties covering capacity below 70%. Document your battery health regularly. Our reports can support warranty claims if degradation exceeds normal rates.
Understanding State of Health (SOH)
What is SOH?
State of Health (SOH) is expressed as a percentage comparing your battery's current maximum capacity to its original capacity when new. For example, a battery with 90% SOH can store 90% of the energy it could when brand new.
SOH Benchmarks:
- ✓95-100% SOH: Excellent - Battery is like new
- ✓85-94% SOH: Good - Normal degradation for 3-5 year old vehicles
- !75-84% SOH: Fair - Consider professional assessment
- ✗Below 75% SOH: Concerning - May affect warranty, requires inspection
How We Measure SOH
Our diagnostic equipment connects directly to your vehicle's battery management system (BMS) to retrieve accurate capacity data. We don't rely on the dashboard display, which can be optimistic. Our professional tools provide the real numbers you need for buying, selling, or maintaining your EV.
Best Practices for Battery Longevity
The 20-80 Rule
Keep your battery between 20% and 80% for daily driving. This range minimises stress on the battery cells and significantly extends battery life. Only charge to 100% before long trips.
Avoid Extreme Temperatures
Both extreme heat and cold accelerate degradation. Park in shaded or covered areas when possible. In winter, precondition your battery while still plugged in to reduce range impact and battery stress.
Minimise DC Fast Charging
While convenient, frequent DC fast charging generates more heat and stress than AC charging. Reserve fast charging for road trips and use Level 2 charging for daily needs.
Regular Driving
Batteries that sit unused for extended periods can degrade faster. If storing your EV, maintain charge around 50% and drive it at least once a month.
Monitor Battery Health
Get professional battery health checks annually, or before major decisions like selling or when noticing performance changes. Early detection of issues can prevent costly problems.
When to Get a Professional Check
Consider getting a professional battery health check if you:
- •Are considering buying a used EV (essential for pre-purchase)
- •Notice more than 20% range reduction from new
- •Are approaching warranty expiration (document baseline health)
- •Experience unusual charging behaviour or battery warnings
- •Plan to sell your EV (transparency builds buyer confidence)
- •Want annual health monitoring for peace of mind
