How Car Battery Modules Combine High and Low Voltage Systems
A self-contained battery module that houses both high and low voltage batteries, a power converter, and safety switches in a single unit designed for efficient heat management.
Original patent title: “Battery system module”
A self-contained battery module that houses both high and low voltage batteries, a power converter, and safety switches in a single unit designed for efficient heat management. Granted to Johnson Controls Technology Co in 2004 with 46 claims and 46 forward citations, and it is now in the public domain.
Coverage
What does this patent actually cover?
This patent describes an integrated battery module for vehicles that packs a high-voltage battery (for heavy loads like motors) and a low-voltage battery (for electronics) into one container. It includes a DC-to-DC converter to move power between the two batteries and safety switches that automatically cut power if the container is opened or a service door is accessed. The design also features specific cooling paths and apertures to move heat out of the box, ensuring both the batteries and the converter stay within safe operating temperatures.
The gap
What does this patent NOT cover?
- Does not cover battery systems that lack an integrated DC-to-DC converter.
- Does not cover systems that rely solely on liquid cooling rather than the described air-flow paths.
- Does not cover battery modules that do not include a safety disconnect switch triggered by opening the container or a service door.
- Does not cover standalone batteries that lack a secondary low-voltage battery within the same housing.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The invention treats the entire battery module as a single, modular unit that includes its own safety interlocks and thermal management, rather than treating the battery, converter, and cooling system as separate, scattered components in the car chassis.
The Patent Drawing
Schematic visualization of the patent's claim structure. Hand-drawn diagrams in progress for each landmark patent.
Where you've seen this
Real-world examples
Early 42V/12V hybrid vehicle electrical architectures
Integrated battery management units in modern hybrid electric vehicles
Modular automotive power distribution systems
Why it matters
The bigger picture
This patent addressed the early engineering challenges of transitioning to hybrid and electric vehicles, where managing two different voltage levels in a compact, safe space was difficult. By integrating the converter and safety disconnects into a single module, it helped standardize how manufacturers could package power systems for better reliability and easier maintenance.
Filed
October 15, 2002
Granted
December 7, 2004
Market context
Who's building on this
Companies in this space
Major automotive suppliers like Johnson Controls (now Clarios) and various Tier 1 automotive parts manufacturers have built on these concepts. Modern electric vehicle manufacturers continue to refine these integrated power electronics modules to improve energy density and safety.
Market impact
This patent helped define the 'modular' approach to automotive power systems, allowing car makers to treat complex battery-converter setups as single parts. This shift simplified assembly line processes and established early safety standards for high-voltage maintenance in hybrid vehicles.
Claim 1 — Plain English
What this patent covers
This patent describes an integrated battery module for vehicles that packs a high-voltage battery (for heavy loads like motors) and a low-voltage battery (for electronics) into one container. It includes a DC-to-DC converter to move power between the two batteries and safety switches that automatically cut power if the container is opened or a service door is accessed. The design also features specific cooling paths and apertures to move heat out of the box, ensuring both the batteries and the converter stay within safe operating temperatures.
The clever bit
The invention treats the entire battery module as a single, modular unit that includes its own safety interlocks and thermal management, rather than treating the battery, converter, and cooling system as separate, scattered components in the car chassis.
What it does not cover
- Does not cover battery systems that lack an integrated DC-to-DC converter.
- Does not cover systems that rely solely on liquid cooling rather than the described air-flow paths.
- Does not cover battery modules that do not include a safety disconnect switch triggered by opening the container or a service door.
- Does not cover standalone batteries that lack a secondary low-voltage battery within the same housing.
Patent timeline
Application submitted to the patent office
Application published, typically 18 months after filing
Patent officially issued
Patent enters public domain
This patent is in the public domain
See the Freedom to Build guide — what is free to use, what is not, and how to cite this patent.
PatentBrief Score
Impact Score
Strong
Citation count
33/40
Moderately cited
Claim breadth
20/20
Very broad protection
Recency
0/20
Older than 20 years
Assignee scale
20/20
Major company or institution
PatentBrief Impact Score — based on citation count, claim breadth, recency, and assignee scale. Not a legal assessment.
Heuristic Value Estimate
What this patent might be worth
$38K – $121K
Midpoint $76K · expired or expiring · industry ×1.4
Heuristic only — blends forward/backward citation counts, claim scope, time remaining, litigation history, and CPC-derived industry baseline. Real valuations need a professional appraisal.
Claim text not yet imported for this patent
The original legal language
Original claims
46 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Chen, C. Y., Green, T. J., Klos, S. G., Iverson, M. E., Gondek, M. M., & Dougherty, T. J. (2004). How Car Battery Modules Combine High and Low Voltage Systems (U.S. Patent No. 6,828,755). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/6828755/battery-system-module
Auto-generated from the patent record. Double-check author order and the issue date against the official USPTO document before submitting.
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Common Questions
Frequently Asked Questions
What does How Car Battery Modules Combine High and Low Voltage Systems cover?
A self-contained battery module that houses both high and low voltage batteries, a power converter, and safety switches in a single unit designed for efficient heat management.
Who owns patent US 6828755?
Johnson Controls Technology Co owns this patent, granted in 2004.
When does this patent expire?
This patent has expired and is now in the public domain — anyone can use the invention freely.
What is patent US 6828755 cited by?
This patent has been cited by 46 later patents that build on its ideas.
What problem does this patent solve?
This patent addressed the early engineering challenges of transitioning to hybrid and electric vehicles, where managing two different voltage levels in a compact, safe space was difficult. By integrating the converter and safety disconnects into a single module, it helped standardize how manufacturers could package power systems for better reliability and easier maintenance.
What does this patent NOT cover?
Does not cover battery systems that lack an integrated DC-to-DC converter.
Patent monitoring