EV Battery Pack Architecture, Cell-to-Pack (CTP) Integration & Energy Density
EV Cell-to-Pack (CTP) Gravimetric & Volumetric Efficiency Formula
Calculate Nominal Pack Energy (kWh), Gravimetric Cell-to-Pack Mass Ratio GCTP (%), Volumetric Cell-to-Pack Space Utilization VCTP (%), and Pack-Level Specific Energy (Wh/kg).
Eliminating intermediate module housings lifts volumetric cell-to-pack utilization from ~50% past 65%—letting LFP match older NMC pack range!
A bare battery cell boasting 266.67 Wh/kg (560 Wh / 2.10 kg) loses 20%–35% of its gravimetric energy density and 35%–50% of its volumetric energy density once assembled with cold plates, busbars, BMS harnesses, crash side-rails, and module housings! Cell-to-Pack (CTP) structural blade/prismatic architectures eliminate intermediate sub-modules, tracked by two core packaging ratios over N cells: Gravimetric Cell-to-Pack Efficiency GCTP% = ((N * m_cell) / M_pack) * 100 and Volumetric Cell-to-Pack Utilization VCTP% = ((N * V_cell) / V_pack) * 100, yielding Pack-Level Specific Energy E_pack_spec = (N * E_cell_Wh) / M_pack = Cell_Wh_kg * (GCTP% / 100)!
Verify on a 120-Cell Structural Blade CTP Pack—Cell_Count N = 120 (B2), Single_Cell_Mass = 2.10 kg (B3 -> 252.0 kg bare cells), Single_Cell_Energy = 560.0 Wh (B4 -> Nominal Pack = 67.20 kWh in E2), Single_Cell_Volume = 0.95 L (B5 -> 114.0 L bare cells), Total_Pack_Mass = 315.0 kg (B6), and Total_Enclosure_Volume = 175.0 L (B7): Gravimetric CTP Efficiency hits 80.00% (E3), Volumetric CTP Utilization reaches 65.14% (E4), and Pack-Level Specific Energy lands at 213.33 Wh/kg (E5)! When your pack engineering team stores this workbook in Arte Sheets cloud collaboration, external OAuth tools such as the Arte Sheets ChatGPT `0.1.0` connector (currently `In review` / `Not published`; `Profile -> Connected apps`) can inspect `read_range` (`<= 200` cells) raw formulas and the base `revision` without consuming Arte AI credits (subject to the `120` calls/min per-account limiter, while ChatGPT credits never transfer to the metered in-app Pro Assistant).
| CTP Packaging KPI (120 Cells x 2.10 kg / 560 Wh / 0.95 L in 315 kg / 175 L) | Formula | Verified Output |
|---|---|---|
| Nominal Pack Energy (kWh) | (Cell_Count * Cell_Energy_Wh) / 1000 | 67.20 kWh |
| Gravimetric CTP Ratio GCTP (%) | ((N * Cell_Mass_kg) / Pack_Mass_kg) * 100 | 80.00% (66.32% @ 380 kg CTM) |
| Volumetric CTP Ratio VCTP (%) | ((N * Cell_Vol_L) / Pack_Vol_L) * 100 | 65.14% (49.57% @ 230 L CTM) |
| Pack Specific Energy (Wh/kg) | (N * Cell_Energy_Wh) / Pack_Mass_kg | 213.33 Wh/kg (176.84 @ 380 kg CTM) |
Cell-to-Pack Gravimetric & Volumetric Integration Efficiency Formula
Validate Cell_Count >= 1, positive cell mass/energy/volume, and physically consistent Pack_Mass > N * Cell_Mass and Pack_Volume > N * Cell_Volume (an enclosure with busbars and cold plates cannot weigh less or occupy less space than its bare cells)!
=LET(nc_l, B2, mc_k, B3, ec_w, B4, vc_l, B5, mp_k, B6, vp_l, B7, IF(OR(nc_l < 1, mc_k <= 0, ec_w <= 0, vc_l <= 0, mp_k <= nc_l * mc_k, vp_l <= nc_l * vc_l), "Invalid CTP Pack Input", ROUND((nc_l * ec_w) / mp_k, 2)))Legacy Cell-to-Module-to-Pack (CTM) Overhead Penalty Check (Set Pack = 380 kg & 230 L)
Compare legacy sub-module housings using the exact same 120 cells (set Pack_Mass B6 = 380.0 kg and Pack_Volume B7 = 230.0 L): Gravimetric Efficiency E3 drops to 66.32%, Volumetric Utilization E4 plunges to 49.57%, and Pack Specific Energy E5 falls from 213.33 Wh/kg down to 176.84 Wh/kg!
=IF(ISTEXT(E5), E5, ROUND(((B2 * B5) / B7) * 100, 2))Try the example
Use the original values or change them to test your understanding.