How Electric Cars Adjust Charging Speed to Available Power
This patent describes how an electric vehicle's onboard charger intelligently adjusts its charging speed based on the real-time electrical power available from the wall outlet or charging station, preventing overloads and optimizing charge time.
Original patent title: “Ac current control of mobile battery chargers”
This patent describes how an electric vehicle's onboard charger intelligently adjusts its charging speed based on the real-time electrical power available from the wall outlet or charging station, preventing overloads and optimizing charge time. Owned by Tesla Motor with 16 claims and 11 forward citations, and it is expected to expire in 2030.
Coverage
What does this patent actually cover?
The patent describes a system and method for an electric vehicle to manage its battery charging from an AC power source. It works by first figuring out the maximum amount of DC current the vehicle can safely draw, based on how much AC current or power is actually available at that moment (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 1a, 5a). Then, the onboard charging system provides an actual DC charging current to the battery, making sure it doesn't go over that calculated maximum (Claim 1b, 5b). For example, if you plug your Tesla into a household outlet, the car's system checks how much power that outlet can safely provide and then charges the battery as fast as possible without tripping the circuit breaker. More complex versions use control loops to fine-tune this process, comparing target voltages and currents to actual readings (Claim 2, 4).
The gap
What does this patent NOT cover?
- Does not cover charging systems that do not adapt to real-time available AC current or power.
- Does not cover off-board charging systems where the charger is external to the vehicle.
- Does not cover charging methods that only establish a fixed maximum DC current without responsiveness to real-time AC source conditions.
- Does not cover systems that lack a controller to adjust actual DC charging current based on input AC current (ClaimclaimA numbered sentence at the end of a patent that legally defines what the inventor owns. The most important section.Read more → 3).
- Does not cover charging of non-electric vehicle energy storage systems.
These exclusions are unique to PatentBrief — derived from the actual claim language, not patent-office boilerplate.
Key facts
What made this novel
The noveltynoveltyThe requirement that an invention be different from anything publicly known before its priority date.Read more → lies in the system's ability to establish a real-time maximum DC charging current based on the actual available AC power, rather than just a pre-set limit. This dynamic adjustment optimizes charging speed while preventing electrical overloads.
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
Tesla Model S onboard charger
Tesla Model 3 onboard charger
Most modern electric vehicle onboard charging systems
Portable EV charging cables with adjustable current settings
Why it matters
The bigger picture
This patent is significant because it addresses a core challenge in electric vehicle charging: safely and efficiently using varied AC power sources. By dynamically adjusting the charging current, it allows EVs to charge at the fastest possible rate without overloading electrical circuits, which is crucial for user convenience and grid stability. This capability is fundamental to modern EV charging, enabling vehicles to adapt to different charging environments, from standard home outlets to dedicated charging stations.
Filed
October 13, 2010
Market context
Who's building on this
Companies in this space
Tesla, as the original assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →, continues to develop and implement advanced charging technologies in its vehicles. Other major automotive manufacturers like General Motors, Ford, Volkswagen, and Hyundai also incorporate similar intelligent onboard charging systems in their electric vehicle lineups to optimize charging performance and safety.
Market impact
This patent's underlying principles have become standard practice in the electric vehicle industry. It enabled more flexible and safer charging experiences for EV owners, allowing them to plug into various power sources without manual configuration or risk of overloading circuits. This adaptability was crucial for broader EV adoption and helped establish expectations for smart charging capabilities in the market.
Claim 1 — Plain English
What this patent covers
The patent describes a system and method for an electric vehicle to manage its battery charging from an AC power source. It works by first figuring out the maximum amount of DC current the vehicle can safely draw, based on how much AC current or power is actually available at that moment (Claim 1a, 5a). Then, the onboard charging system provides an actual DC charging current to the battery, making sure it doesn't go over that calculated maximum (Claim 1b, 5b). For example, if you plug your Tesla into a household outlet, the car's system checks how much power that outlet can safely provide and then charges the battery as fast as possible without tripping the circuit breaker. More complex versions use control loops to fine-tune this process, comparing target voltages and currents to actual readings (Claim 2, 4).
The clever bit
The novelty lies in the system's ability to establish a real-time maximum DC charging current based on the actual available AC power, rather than just a pre-set limit. This dynamic adjustment optimizes charging speed while preventing electrical overloads.
What it does not cover
- Does not cover charging systems that do not adapt to real-time available AC current or power.
- Does not cover off-board charging systems where the charger is external to the vehicle.
- Does not cover charging methods that only establish a fixed maximum DC current without responsiveness to real-time AC source conditions.
- Does not cover systems that lack a controller to adjust actual DC charging current based on input AC current (Claim 3).
- Does not cover charging of non-electric vehicle energy storage systems.
Patent timeline
Application submitted to the patent office
Patent enters public domain
PatentBrief Score
Impact Score
Early stage
Citation count
22/40
Moderately cited
Claim breadth
11/20
Broad claimsclaimsThe numbered statements at the end of a patent that legally define what the inventor owns.Read more →
Recency
0/20
Older than 20 years
Assignee scale
0/20
Independent or smaller assigneeassigneeThe entity that owns the patent — usually the inventor's employer or a company.Read more →
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
$51K – $163K
Midpoint $102K · 4.2 yr remaining · 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
16 claims as filed with the patent office.
Concepts involved
Citations
Patent lineage
Cite this patent
Paryani, A., Nergaard, T. A., & Baglino, A. How Electric Cars Adjust Charging Speed to Available Power (U.S. Patent No. 20,120,091,953). U.S. Patent and Trademark Office. https://patentbrief.org/patent/us/20120091953/ac-current-control-of-mobile-battery-chargers
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 Electric Cars Adjust Charging Speed to Available Power cover?
This patent describes how an electric vehicle's onboard charger intelligently adjusts its charging speed based on the real-time electrical power available from the wall outlet or charging station, preventing overloads and optimizing charge time.
Who owns patent US 20120091953?
This patent is owned by Tesla Motor.
When does this patent expire?
This patent is expected to expire on October 13, 2030, when the invention enters the public domain.
What is patent US 20120091953 cited by?
This patent has been cited by 11 later patents that build on its ideas.
What problem does this patent solve?
This patent is significant because it addresses a core challenge in electric vehicle charging: safely and efficiently using varied AC power sources. By dynamically adjusting the charging current, it allows EVs to charge at the fastest possible rate without overloading electrical circuits, which is crucial for user convenience and grid stability. This capability is fundamental to modern EV charging, enabling vehicles to adapt to different charging environments, from standard home outlets to dedicated charging stations.
What does this patent NOT cover?
Does not cover charging systems that do not adapt to real-time available AC current or power.
Patent monitoring