EV·BAT

Technical Guide v2.0

EV BATTERY ARCHITECTURE

From 400V and 800V systems to cell chemistry, from series-parallel connections to pack structure — the complete technical guide to EV batteries.

5Chemistries

3Hierarchy

2Architecture

01 — System Voltage

400V vs 800V ARCHITECTURE

Electric vehicles use two main high-voltage system architectures. The number and arrangement of cells are planned according to this target voltage.

400V

Standard Architecture

Typical voltage range350 – 450 V
Series cell count (3.7V)~108 hücre
Series cell count (3.2V LFP)~125 hücre
Max. charging current~250 A
Max. charging power~150 kW
Charging time (10→80%)~25–35 dk
Cable cross-sectionThick, heavy

Tesla Model 3 (eski) VW ID.4 Nissan Ariya Ford Mustang Mach-E BMW iX3

800V

High-Performance Architecture

Typical voltage range700 – 900 V
Series cell count (3.7V)~216 hücre
Series cell count (3.2V LFP)~250 hücre
Max. charging current~500 A
Max. charging power~350 kW+
Charging time (10→80%)~18–22 dk
Cable cross-sectionThin, lightweight

Porsche Taycan Audi e-tron GT Hyundai Ioniq 6 Kia EV6 Mercedes EQS

P = V × I → Why 800V is Better?

⚡ Same power, half current

For 350 kW power, 400V system requires 875A current, while 800V system only needs 437A.

🌡 Less heat

Heat loss is proportional to the square of the current (P=I²R). Half current = ¼ heat loss. Thermal management becomes easier.

⚖️ Lighter cables

Lower current allows thinner cables, reducing vehicle weight.

02 — Circuit Topology

SERIES and PARALLEL CONNECTION

Depending on how cells are connected, voltage or capacity increases. Real batteries combine both.

SERIES CONNECTION

Cells are connected positive (+) terminal to negative (−) terminal of the next cell. Voltages add up, current capacity remains the same as a single cell.

Voltage V_toplam = V₁ + V₂ + V₃ ... = n × V_hücre

Current I_toplam = I_hücre (değişmez)

Capacity C_toplam = C_hücre (değişmez)

Example 4 × 3.7V = 14.8V / 50Ah = 50Ah

Note: Caution: If one cell in a series connection loses capacity, the whole pack is affected. Therefore, the BMS (Battery Management System) keeps cells balanced.

PARALLEL CONNECTION

All positive (+) terminals are connected together, and all negative (−) terminals are connected together. Voltage stays constant, current capacity and total energy increase.

Voltage V_toplam = V_hücre (değişmez)

Current I_toplam = I₁ + I₂ + I₃ = n × I_hücre

Capacity C_toplam = n × C_hücre

Example 3.7V sabit / 3 × 50Ah = 150Ah

Parallel connection increases range. Current distributes equally among cells; a single cell failure does not stop the entire pack — providing higher safety.

COMBINED (nS × mP)

Real EV batteries use both together. First, parallel groups (P) are formed, then these groups are connected in series (S). Notation: "96S2P" = 96 series × 2 parallel.

Voltage V = n_seri × V_hücre

Capacity C = n_paralel × C_hücre

Energy E (kWh) = V × C / 1000

Example 96S3P · 3.65V · 75Ah

Bottom line 350V · 225Ah = 78.75 kWh

Tesla Model 3: 96S·xP configuration. Panasonic 2170 cells.

03 — Manufacturing Process

CELL AND PACK STRUCTURE

How does a lithium-ion cell become a complete battery starting from electrode production, and how is it placed into a pack?

Cylindrical

18650 / 21700 / 4680

Winding technique. Standard size, high production volume. Tesla 4680 cell uses this format. Easy thermal management.

TeslaPanasonic

Pouch

Esnek laminat kılıf

Stacking technique. Thin and lightweight, high space utilization (>90%). Requires mechanical support due to swelling risk.

LGSK On

Prismatic

Sert alüminyum kasa

Rigid metal casing. High mechanical strength. BYD Blade cell uses this format — used directly as a module (CTP).

BYDCATL

Cell Manufacturing Process

Electrode Mixing

Active material (cathode/anode powder), conductive carbon black, and binder (PVDF) are mixed in NMP solvent. A homogeneous slurry is obtained.

Coating & Drying

Slurry is precisely coated onto aluminum (cathode) or copper (anode) foil. Solvent is evaporated in long ovens, forming a porous electrode film.

Calendering & Cutting

Electrode foils are passed through calendering rolls to increase density. Then they are laser-cut to the desired size.

Assembly & Electrolyte

Cathode / separator / anode layers are wound or stacked. Placed into the casing, filled with electrolyte, vacuum sealed. Formation involves initial charge-discharge cycles.

04 — Cathode Chemistry

LFP · NMC · NCA · LMO

Cathode material directly determines the battery\'s voltage, energy density, safety, and lifespan.

LFP

LiFePO₄ — Lityum Demir Fosfat

En güvenli ve en uzun ömürlü kimya. Termal kaçış riski yok. Enerji yoğunluğu düşük ama maliyet avantajı büyük. Tesla Standart Menzil modelleri ve BYD bunu kullanır.

Energy Density120–160 Wh/kg

Safety★★★★★

Cycle Life3000–5000+

CostLow

Nominal voltage: 3.2V/hücre

NMC

LiNiMnCoO₂ — Nikel Mangan Kobalt

En yaygın kullanılan kimya. Nikel, mangan ve kobalt oranı değiştirilerek güç/enerji dengesi ayarlanabilir. NMC811 (yüksek Ni) premium araçlarda, NMC532 daha uygun fiyatlılarda kullanılır.

Energy Density200–280 Wh/kg

Safety★★★☆☆

Cycle Life1000–2000

CostMedium

Nominal voltage: 3.6–3.7V/hücre

NCA

LiNiCoAlO₂ — Nikel Kobalt Alüminyum

Enerji yoğunluğu en yüksek kimya. Tesla Model S/X bu kimyayı Panasonic ile kullandı. Alüminyum katkısı ısıl kararlılık sağlar fakat kobalt içeriği maliyeti artırır.

Energy Density240–300 Wh/kg

Safety★★☆☆☆

Cycle Life500–1500

CostHigh

Nominal voltage: 3.65V/hücre

LMO

LiMn₂O₄ — Lityum Mangan Oksit

Spinel yapısı sayesinde iyi güç çıkışı sağlar. Mangan ucuz ve bol bulunur. Yüksek sıcaklıkta mangan çözünmesi sorunu döngü ömrünü kısaltır. Genellikle NMC ile karıştırılır.

Energy Density100–150 Wh/kg

Safety★★★★☆

Cycle Life300–700

CostVery Low

Nominal voltage: 3.8V/hücre

Quick Comparison

Chemistry	Voltage	Life	Usage
LFP	3.2V	5000+ döngü	Broad Segment
NMC	3.7V	1000–2000	Premium/Mid
NCA	3.65V	500–1500	High Perf.
LMO	3.8V	300–700	Mixed/Older

05 — Future Technology

SOLID-STATE BATTERIES

Next-generation battery technology targeting higher energy density, better safety, and longer lifespan by replacing liquid electrolyte with solid conductors.

Key Differences vs Lithium-Ion

Li-İon

Solid-State

Electrolyte

Liquid organic (flammable)

Solid ceramic / polymer / sulfide

Safety

Thermal runaway risk

No thermal runaway, minimal fire risk

Energy Density

~250–300 Wh/kg

~400–500 Wh/kg (target)

Anode

Graphite

Lithium metal (10× thinner)

Operating Temp.

Wide range

Limited in some types (polymer)

Dendrite Risk

Moderate (prevented by separator)

Still under research

Solid Electrolyte Types

Oxide

LLZO — Li₇La₃Zr₂O₁₂

High chemical stability, resistant to air and moisture. Lower ionic conductivity than others. Toyota and QuantumScape work in this area.

Safety★★★★★

Ionic ConductivityMedium

Toyota QuantumScape Murata

Sulfide

Li₆PS₅Cl (Argyrodite)

Highest ionic conductivity — comparable to liquid electrolytes. Samsung SDI and Solid Power prefer this chemistry. Reaction with moisture causes problems.

Safety★★★★☆

Ionic ConductivityHigh

Samsung SDI Solid Power Panasonic

Polymer

PEO — Polietilen oksit

Flexible, lightweight, and relatively easy to manufacture. Works well above 60–80°C; conductivity drops at room temperature. Bolloré Blue Car was based on this technology.

Safety★★★★☆

Ionic ConductivityLow (room temp)

Bolloré Seeo Ionic Materials

Key Challenges & Roadmap

Manufacturing Cost

Dry room environments and precise manufacturing processes make costs 3–5× higher than current Li-ion cells. Scale economy not yet established.

Solid-Solid Interface

Mechanical stress forms between electrode and electrolyte during charge-discharge cycles. Volume change can lead to loss of contact.

Dendrite Formation

Needle-like lithium growths (dendrites) can form when using lithium metal anodes. Creates short-circuit risk; compressive resistance of solid electrolyte is critical.

Industry Roadmap

2025–2027: First hybrid SS cells in mass-production vehicles (e.g. Toyota, Nissan)

2028–2030: Full solid-state pack integration into vehicle floor, 400+ km range increase

2030+: Complete replacement of graphite anode with lithium metal, charging time below 10 min

06 — Structural Hierarchy

CELL → MODULE → PACK

Every EV battery is organized in a three-level hierarchy. Each level handles its own mechanical, electrical, and thermal tasks.

CELL

Fundamental unit of electrochemical energy storage. Contains cathode, anode, separator, and electrolyte. Produces 3–5V.

— Voltage: 3.2–3.8V
— Capacity: 3–300 Ah
— Unit monitored by BMS
— 3 formats: cylindrical, pouch, prismatic

MODULE

Intermediate structure formed by connecting multiple cells in series/parallel. Contains mechanical protection, cooling channels, and busbars.

— Typical: 12–24 cells/module
— Voltage: ~40–100V
— Replaceable service unit
— CTP technology skips the module

PACK

Final structure containing all modules, BMS electronics, cooling system, and safety circuits. Integrated into the vehicle floor.

— Total voltage: 350–900V
— Energy: 40–200 kWh
— BMS monitors all cells
— IP67/IP68 water resistance

CTP

Next Gen

Cell-to-Pack — Module-less Architecture

In this technology pioneered by BYD Blade and CATL, the module layer is eliminated. Cells become structural elements of the pack. Pack volume utilization increases by 15–20%, energy density rises, weight decreases. Fewer parts = fewer failure points.

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