through Design, Thermal Management, and Revival Techniques
Abstract
Battery life (longevity) is a cornerstone of electric vehicle (EV) sustainability, particularly in fleet-heavy regions like India, where high usage, climate stress, and inconsistent charging behaviours accelerate degradation.
At Yanti Innovative Electromotive Solutions, we focus on a revival-first approach to extend the functional life of EV batteries. Our methods emphasize thermal management, string-level IR correction, and real-time monitoring of voltage elasticity, defined as a cell’s ability to return to nominal voltage after a discharge.
Through this combination, we have achieved over 70% revival success across battery packs ranging from 1kWh to 40kWh. Voltage-based diagnostics often expose weak strings incapable of coping with controlled discharge profiles, prompting targeted replacements that recover elasticity and reduce internal resistance. Depending on chemistry, our revived packs gain 18–36 months of extended use and are backed by AMC-supported warranties to ensure continued fleet confidence.
We further present real-world limitations of phase change materials (PCMs) in two-wheeler batteries and share alternative thermal strategies. Looking ahead, solid-state batteries hold promise for safety and density improvements, and we are closely tracking their viability. This paper provides field-driven insights into battery recovery, cooling design, and data-backed revival to support a longer-lasting, lower-waste EV ecosystem.
Voltage Elasticity and Cell Health
Voltage elasticity—the ability of a cell to recover its nominal voltage post-discharge—is one of the earliest indicators of battery degradation. As a battery undergoes repeated cycling, ion mobility reduces, electrode material fatigues, and internal resistance (IR) rises. These electrochemical shifts not only diminish available capacity but also interfere with the battery’s voltage recovery.
In our lab and field work, we observe that cells with poor elasticity often show inconsistent discharge curves, especially under voltage-based cutoffs. These weaknesses often lie within specific strings. By identifying such behaviour early, we replace underperforming strings, significantly reducing IR and restoring the voltage recovery profile of the entire pack.
We recommend using real-time impedance spectroscopy to measure this elasticity loss. This allows early intervention and enables predictive maintenance for large fleets.
Phase Change Materials (PCMs) Failure in Two-Wheeler Batteries
Many two-wheeler EV manufacturers adopted Phase Change Materials for passive thermal management. However, in our revival work, PCM-equipped batteries frequently exhibit localized thermal stress and early failure. This is largely due to PCM’s low thermal conductivity and heat dissipation limits in compact environments.
Why PCMs Fail:
- PCM layers saturate quickly in high-load scenarios.
- Lack of airflow or external cooling prevents effective heat rejection.
- Heat remains trapped, damaging cells and elevating IR.
Alternative Solutions Explored:
- Graphene-based thermal films
- Microchannel aluminium heat exchangers
- Low-profile liquid cooling modules
These alternatives have shown consistent ΔT reductions across cells during charging and discharging cycles. Integrating such systems could become the norm in performance two-wheeler EVs.
Data-Driven Insights from Battery Revival
Yanti’s revival facilities currently achieve a 70% success rate for batteries from 1 kWh to 40 kWh. Our multi-stage diagnostic process focuses on:
- Identifying high-IR strings
- Monitoring voltage elasticity under load
- Rebalancing cell groups
When string voltages fail to hold during controlled discharges, they indicate localized fatigue or poor assembly. These strings are flagged and replaced.
We also track the pack delta (Δ) between the lowest and highest string voltages at full charge and full discharge. Unacceptable deltas often correlate with:
- Uneven cell aging
- Suboptimal BMS parameters
- Inadequate cooling or thermal gradients
- External temperature and charging misuse
| Metric | Typical Value / Range | Notes |
|---|---|---|
| IR Reduction | 20–40% post-string replacement | Achieved via selective swapping and reconditioning |
| Voltage Elasticity Recovery | Notable improvement in 3P strings | Seen in packs where weak strings were isolated |
| Cycle Life Gained | +1,000 to +2,500 cycles | Chemistry-dependent |
| Extended Lifespan | 18–36 months | NMC: ~18–24, LFP: ~24–30, LTO: ~30–36 months |
| Post-Revival Warranty | AMC-backed, up to 24 months | Available for commercial clients and fleet operators |
| Success Rate (by kWh range) | 70% across 1kWh–40kWh packs | Applicable to 2W, 3W, 4W traction systems |
Proactive Maintenance for Long-Term Battery Health
Despite popular belief, EV batteries are not “fit-and-forget” components. Without routine diagnostics, minor imbalances evolve into system-level failures.
Yanti’s maintenance model includes:
- IR and voltage balancing checks
- BMS logging and thermal data review
- Visual inspection of weld joints and busbars
- Cooling flow path verification
This structured AMC-backed plan has led to lower breakdown rates and better performance in fleet environments.
Conclusion
Battery life (longevity) is not solely dependent on chemistry—it is the sum of design, thermal behavior, maintenance, and the ability to intervene mid-life through intelligent diagnostics. Yanti’s revival techniques have extended EV battery life by thousands of cycles, kept 70% of batteries out of scrap, and provided AMC-warranted confidence for second-life usage.
We are committed to pushing beyond current thermal management and revival standards, and look forward to integrating solid-state and next-gen materials as they mature.
About Yanti
Headquartered in Gurugram, India, Yanti Innovative Electromotive Solutions Pvt Ltd is building the country’s first platform dedicated to EV battery reliability and interoperability. With over 7 years of field expertise across NMC, LFP, and LTO chemistries, Yanti combines deep revival IP with advanced diagnostics like voltage elasticity mapping and string-level IR correction. Beyond repair, Yanti is pioneering cross-make BMS interoperability, helping fleets, financiers, and OEMs unlock value from failed or repossessed packs. By feeding real-world failure insights back into thermal and electrical design, Yanti is shaping the future of design-for-reliability in India’s EV ecosystem.
Contact: Romesh Gupta, Founder & Managing Director, romesh@yanti.co.in