EV Battery Health — Frequently Asked Questions
Everything about battery degradation, real range, and maintaining your EV's health.
What is Battery State of Health (SoH)? ▼
Battery State of Health (SoH) is a percentage indicating your EV battery's current capacity versus its original factory capacity. A new battery starts at 100% SoH. As it ages through charging cycles and calendar aging, SoH gradually decreases — for example, 85% SoH means your battery holds 85% of its original charge.
Why do different EV models degrade at different rates? ▼
Degradation depends on battery chemistry (LFP batteries like BYD degrade slower than NMC), thermal management (liquid-cooled systems in Tesla and MG protect better than air-cooled ones), BMS quality, and build standards. Premium EVs with liquid cooling can maintain 90%+ health after 5 years.
Why is real-world range lower than ARAI/WLTP claims? ▼
ARAI and WLTP tests use controlled lab conditions with optimal temperatures, no AC, smooth roads, and gentle driving. Real-world conditions including traffic, AC usage, hills, extreme temperatures, and payload reduce actual range by 20–40% compared to claimed figures.
Does fast charging damage EV batteries? ▼
Fast charging generates more heat and cell stress, accelerating degradation if overused. Impact varies by vehicle: liquid-cooled EVs (Tesla, BYD, MG ZS EV) handle it with only 2–3% extra penalty, while air-cooled EVs like the older Tata Nexon EV can see 8–10% faster degradation. Aim for slow AC charging for 70–80% of your needs.
Is it safe to buy a used EV with 50,000 km? ▼
Yes, if battery health is above 85%. A well-maintained EV with 50,000 km and 3–4 years of age should retain 88–92% battery health. Always get a professional battery health check before buying. Most manufacturers offer 8-year or 1.6 lakh km warranty. Avoid EVs below 80% health unless heavily discounted.
How does extreme heat affect EV battery health in India? ▼
Extreme heat (40°C+) accelerates degradation, but impact depends on thermal management. Liquid-cooled EVs add only ~1.5% penalty per year in extreme heat, while air-cooled EVs can add 2.5–3% per year. EVs in Delhi, Rajasthan, or Gujarat degrade faster than those in Bangalore or Kerala.
What is the difference between LFP and NMC batteries? ▼
LFP (Lithium Iron Phosphate) batteries used in BYD have slower degradation (0.8% per year), better safety, and 3000+ cycle lifespan but lower energy density. NMC (Nickel Manganese Cobalt) batteries in most other EVs offer higher energy density and longer range, but degrade faster (1–2% per year) with 1500–2000 cycles.
Which Indian EV has the best battery longevity? ▼
Based on battery chemistry and thermal management: BYD Atto 3/e6 (LFP + liquid cooling) and Tesla Model 3/Y lead the pack. MG ZS EV and Hyundai Ioniq 5 follow closely with liquid cooling. Tata Nexon EV Max is improved over the base model. Air-cooled EVs like the Tata Tiago EV degrade fastest in Indian heat.
How the EV Battery Health Calculator Works
Our EV battery health calculator uses a vehicle-specific degradation algorithm that factors in four key variables: calendar aging (time-based degradation), cycle aging (mileage-based wear), fast-charging stress, and climate impact. Each EV model in our database has unique parameters based on its battery chemistry (LFP vs NMC), thermal management system (liquid vs air cooling), and real-world efficiency data.
Understanding Battery State of Health (SoH)
State of Health represents your battery's current maximum capacity as a percentage of its original capacity. A new EV starts at 100% SoH. Most modern EVs lose 1–3% per year depending on usage and climate. The industry considers a battery at end of EV life at 70–80% SoH, at which point it can still be repurposed for stationary energy storage.
ARAI Range vs Real-World Range in India
ARAI (Automotive Research Association of India) tests EV range in controlled lab conditions. In real-world Indian driving — with traffic, AC usage, highway speeds, and summer heat — you can expect 20–40% less range than the ARAI claim. Our calculator applies a vehicle-specific real-world factor to give you an honest estimate.
EV Battery Health for Used Car Buyers
If you're considering a used EV, battery health is the single most important factor. Enter the vehicle's age and approximate mileage to estimate current SoH. Avoid used EVs below 80% health unless the price reflects a significant discount. Most manufacturers provide an 8-year / 1,60,000 km battery warranty.
LFP vs NMC — Which Battery Lasts Longer?
LFP (Lithium Iron Phosphate) batteries in BYD vehicles degrade roughly 30–40% slower than NMC. They tolerate full charges better and survive 3,000+ cycles. NMC (Nickel Manganese Cobalt) batteries offer better energy density but degrade faster at 1,500–2,000 cycles. For Indian summers, LFP with liquid cooling offers the best longevity.
Want to compare EV running costs with petrol or diesel? Try our Fuel Cost Calculator. Need to check your vehicle's fuel efficiency? Use the Mileage Calculator.
