Two Stores, One Power Pack: The Physics of Battery–Supercapacitor Hybridisation, the Patented Hybrid Power Pack Architecture, and the Applications Where It Delivers Most

Numerical results are computed from the published WLTC Class 3b regulatory drive cycle and from engine-cranking events, with every model parameter stated.</p><p dir="ltr">Results. When the supercapacitor carries the varying part of the load, the battery's Joule heating falls by 1 − 1/FF², where FF is the ratio of the rms to the mean load current. On the WLTC drive cycle FF is 1.46–2.98 by phase, giving an ideal reduction of 53–89 %.

On engine cranking FF is 5.5–8.7, giving 96.7–98.7 %, and the supercapacitor needed is only 1.40–2.06 Wh of usable energy. For cranking the benefit survives a full system energy balance: the break-even battery resistance is 0.85–5.12 mΩ, several times below the 12.8 mΩ assumed for an illustrative 12.8 V pack.</p><p dir="ltr">Conclusions. The battery–supercapacitor combination is most valuable where the duty cycle is peaky and the pack is small — engine cranking, start–stop, pulse power and fuel-cell buffering — and it is exactly this class of application for which the patented HPP architecture, with its separate battery charge and discharge paths, bidirectional capacitor path and supervising controller, is laid out.

Peer-reviewed studies by other groups of supercapacitor storage, alone or with a battery, across ten sectors report benefits including an almost fivefold extension of starter-battery life, a 7 % fuel-economy gain over battery-only storage in a hybrid vehicle and a 74 % cut in power loss under pulsed load. A defined comparative test programme is proposed to convert the derived HPP results into measured ones.</p><p dir="ltr">Inventor and patents.

The Hybrid Power Pack architecture is protected by granted patents naming Hemant K. Rohera as inventor, including IN 301517, US 10,523,019 B2, JP 6644883 B2, EP 3 320 595 B1 and CA 2,991,527 C (status per the patent family records, 22 September 2026; see Section 8 of the paper).</p><p dir="ltr">Preprint, not peer reviewed. The version of record is on Zenodo; the Zenodo record and the companion paper are listed under Related materials.</p><p dir="ltr">Use of AI-assisted tools: AI-assisted tools were used in drafting, figure generation and reference checking.

The author reviewed and edited all content and takes full responsibility for it.</p><p dir="ltr">Author ORCID: 0009-0005-3275-1743. Full web version: hemant-rohera.vercel.app</p>