EV Battery Degradation: Real Data from Real Cars

If you’ve spent any time in EV comment sections, you’ve seen the claims: “Batteries die after a few years.” “You’ll need a $30k replacement.” “EV range falls off a cliff.” None of these align with real-world data or with what we see across Splend’s own EV fleet. 

This article breaks down what battery degradation is, how it behaves over time, and what our hundreds of fleet battery health readings show across Polestar and Tesla vehicles driven daily by real rideshare and delivery professionals. 

What does “battery degradation” really mean?

Battery degradation is simply the gradual decline in a battery’s ability to store energy. The key measure is SoH (State of Health), the battery’s usable capacity compared to when it was brand-new.

• 100% SoH = the battery stores the full original usable energy

• 95% SoH = it stores 95% of that original energy

• A drop in SoH does not mean sudden failure, it usually means a small reduction in driving range

Example: A vehicle that had 500 km when new, now at 95% SoH, generally delivers around 475 km on a single charge.

This is completely normal. Batteries lose capacity slowly and predictably, not abruptly.

The global research is consistent: slow, steady decline (~1–2% per year) 

Major independent studies report very similar results: 

• Independent telematics company Geotab, analysing data from over 5,000 electric vehicles across 1.5 million vehicle-days, reports an average battery capacity decline of approximately 1.8% per year.

Source: Geotab EV Battery Degradation Study

• Stanford / SLAC National Accelerator Laboratory: Real-world stop-start driving and regenerative braking can make EV batteries last 30–40% longer than lab models. 

Source: Stanford News – Battery longevity study

These independent datasets span multiple climates, driving styles and use cases, and consistently show slow, predictable battery degradation. Splend’s own fleet data aligns closely with these independent findings, despite operating under demanding, high-mileage rideshare conditions.

What Splend’s fleet data shows (real Australian rideshare vehicles) 

Our team analysed over 1,100 SoH readings across Polestar 2, Tesla Model 3, and Tesla Model Y vehicles from the Splend fleet. These EVs operate under demanding, high-mileage conditions typical of rideshare. 

Average SoH across Splend EVs 

• Polestar 2 
  n = 544 readings 
  → 95% avg SoH 
  → Estimated range ≈ 420 km 

• Tesla Model 3 
  n = 250 
  → 95% avg SoH 
  → Estimated range ≈ 385 km 

• Tesla Model Y 
  n = 373 
  → 94% avg SoH 
  → Estimated range ≈ 363 km 

SoH distribution by model (histogram) Dec, 2025

Does battery degradation “kill your range”? Not in our data. 

Even at mid-90s SoH, our range estimates remain very strong and practical for rideshare.

Estimated range vs SoH (box plot) Dec, 2025

“Do EV batteries fall off a cliff?” No. 

There is no evidence of sudden, universal capacity to collapse in modern EVs. Real-world data (ours included) shows gentle, gradual decline. 

Reasons: 

• Regenerative braking reduces heat cycles 

• Modern BMS (Battery Management System) optimises charge behaviour 

• Improved chemistries (NMC, LFP) extend life 

• Larger battery packs operate below stress thresholds 

How EV battery safety is regulated

Modern EV packs must comply with UNECE R100, the international safety standard for thermal propagation, isolation resistance, short circuit protection, and crash integrity. 

Manufacturers like Polestar and Tesla perform: 

• Thermal runaway resistance tests 

• High-voltage isolation checks 

• Pack-level cooling validation 

Source: UNECE R100, InCompliance Magazine

Splend only partners with brands that meet these standards. 

“Will I need a $30,000 replacement battery?” Highly unlikely. 

Real numbers tell a different story: 

• Australian market EV battery replacements typically range $5,000–$16,000 depending on model and pack size 

• Replacement is rare, because batteries last longer than the usable life of many vehicles 

• Prices continue to drop as pack manufacturing scales and modular designs improve 

Source: EV Council

And the safety net: Most OEMs include 8-year / 160,000 km battery warranties with guaranteed minimum capacity thresholds (often 70%). Polestar’s warranty is exactly that. 

How Splend helps drivers feel confident 

Even though degradation is mild and predictable, Splend understands that transparency builds trust, especially for full-time drivers. We offer: 

• Clear SoH data for any Splend EV — no guesswork 

• Optional AVILOO battery testing (independent, industry-standard test used across Europe) 

• Advice on charging habits that extend battery life 

• Splend’s Home EV Advantage Offer for new Pre-Owned Flexi Own Customers who need simple, reliable overnight charging from the convenience of their home 

Splend is the only rideshare membership provider in Australia offering this level of battery-health transparency. 

The reality of EV battery life

Battery degradation is normal, gradual, and far less dramatic than online myths suggest. Independent studies and Splend’s own fleet data show modern EVs retain strong battery health and real-world range for years, even under high-mileage rideshare use.

With long warranties and clear battery health visibility, EVs remain a reliable and practical choice for professional drivers.

EV battery degradation: FAQs

• Do EV batteries degrade quickly? No. Independent studies show most modern EV batteries lose around 1–2% capacity per year on average, meaning they retain strong range for many years.

• What does State of Health (SoH) actually mean? SoH measures how much usable energy a battery can store compared to when it was new. A battery at 95% SoH still delivers around 95% of its original range.

• Will battery degradation affect my ability to drive for Uber? In real-world rideshare use, mid-90% SoH still provides more than enough daily range for full shifts. Splend’s fleet data confirms this across Polestar and Tesla models.

• Will I need to replace the battery? Highly unlikely. Most EV batteries last longer than the working life of the vehicle, and replacement is rare. Manufacturer warranties typically cover batteries for 8 years or 160,000 km.

• Does fast charging ruin EV batteries? Occasional fast charging is fine. Mixing DC fast charging with regular slower AC charging helps manage heat and supports long-term battery health.