Electricity: battery or capacitor charging or discharging – Battery or cell charging – Multi-rate charging
Reexamination Certificate
2001-10-05
2003-02-04
Tso, Edward H. (Department: 2838)
Electricity: battery or capacitor charging or discharging
Battery or cell charging
Multi-rate charging
C320S137000
Reexamination Certificate
active
06515456
ABSTRACT:
BACKGROUND OF THE INVENTIONS
The invention of said prior application, Ser. No. 09/549,541, relates to a “smart” voltage regulator for regulating the voltage of an alternator which, in turn, provides a charging current to a storage battery for improving battery performance by maintaining a proper level of charge, and by reducing sulfation on the surface of the plates.
By way of background, motor vehicles in the United States some years ago typically had six-volt systems comprising, in part, a battery, a direct current (DC) generator, a DC starting motor or starter which, when energized, would start an internal combustion engine which, in turn, would drive the DC generator. A voltage regulator connected to the DC generator would control the output DC voltage thereof.
More recently, most motor vehicles in the United States use twelve-volt systems comprising a twelve-volt battery (12 volt being a nominal output voltage thereof), an alternating current (AC) alternator with appropriate rectifying means for providing a DC current, a DC starter, and a voltage regulator for controlling the voltage output of the alternator. Twelve-volt systems are described herein as a reference. The '541 invention works equally well on any voltage system. The regulation set points are adjusted accordingly.
There are a number of uses or scenarios for the above-described 12-volt system, all of which are based on the internal combustion engine and lead-acid battery combination. One use is with “over-the-road” trucks wherein the engines are operated more or less continuously for long periods of time, and thus, few start-up operations requiring battery current for starting are experienced. A large percentage of “passenger” vehicles make fairly frequent starts (one or more per day) with sufficient run time between each start so as to keep the battery charged. On the other hand, there are a number of applications such as recreational boats, recreational vehicles, and antique and specialty cars wherein such vehicles are operated only occasionally, raising the likelihood of the storage battery used for starting the engine being significantly discharged throughout extended intervals during its life.
Another challenging application for a storage battery is in connection with vehicles that make long stops with loads left on, coupled with very little “run time”. For example, delivery vehicles serving a high-density business section of a metropolitan area typically make long stops with “flashers” left on, coupled with very little run time between stops. The result is storage batteries that are consistently undercharged, shortening the life of the batteries.
The '541 invention actively monitors the needs of the above uses and changes the storage battery charging profile accordingly.
The goal of the present invention is to optimize battery and alternator life. By monitoring a lead-acid battery's state-of-charge (SOC), and by monitoring the conditions the battery and alternator experience, the present invention appropriately adjusts the alternator's output. Vehicle electrical loads are increasing each year (key-off and well as key-on); constant voltage regulators of the prior art are not able to optimally maintain battery health because battery needs vary widely from situation to situation. This results in batteries that are either overcharged (water loss) or undercharged (sulfation). Both situations significantly reduce battery life. The regulator means provided by the present invention works equally well in over-the-road trucks, as well as city delivery trucks, replacing specific voltage settings for specific vehicle use. The combination of high current and high heat can cause alternators to fail. The present invention regulator extends alternator life by preventing damaging combinations of alternator output current and alternator temperature.
DISCUSSION OF THE PRIOR ART
There are, of course, numerous prior art voltage regulator systems for regulating the output voltage of the generator or alternator. Roseman, et al, U.S. Pat. No. 5,623,197 is an example of a prior art system which teaches the decreasing of the output voltage of the alternator when the battery is significantly discharged, to prevent excessive current from entering the battery. Roseman's application concentrates on nickel-cadmium and sealed lead-acid aviation batteries charged by an aviation electrical generator/starter. The present invention concentrates on lead-acid batteries with very different needs.
Current industry technology emphasizes the constant potential method. This method has its disadvantages. It is difficult to have one optimal voltage setting for all conditions. If the voltage setting is too high, overcharging occurs, causing electrolysis (water use) and reduced battery life. If, however, the voltage is set too low, the battery remains undercharge for extended period, causing sulfation, and reduced battery life.
U.S. Pat. No. 5,703,476 suggests that basing the voltage setting on double slope temperature compensation charged the battery better. Temperature, however, is only one factor in the battery's charging needs. Furthermore, battery temperature and regulator temperature are not often correlated. The physical placement of the battery is often different than the voltage regulator, resulting in poor temperature correlation.
The majority of voltage regulator prior art ignores the health of the battery, the primary role of the charging system. Tsuchiya, et al., U.S. Pat. No. 5,929,613, and Peter, et al., U.S. Pat. No. 5,773,964 are examples of this.
SUMMARY OF THE INVENTION
In broad terms, the '541 invention provides a voltage regulator control which is capable of monitoring battery voltage, alternator voltage, voltage regulator temperature, battery temperature, and time. The regulator adjusts the charging profile based on the history of the foregoing five parameters. These parameters have varying importance depending upon the mode of the vehicle.
The primary purpose of the battery in vehicles is to start the engine. Discharged and failing batteries will have longer starts and lower minimum starting voltages. Therefore, it is wise to closely monitor and record voltage and time during starts. Minimum battery voltage during start, length of start, and the integral of delta voltage versus time may all be recorded by the present invention, and used to adjust charging profile. After the engine is started, the present invention charges the battery back as fast as possible without, however, damaging the battery or alternator. The regulator sets its first threshold (Tier D between 15 and 16 volts. It then records how long it takes to get to the Tier I threshold. This value (time) is used later to adjust the charging profile. Fully charged batteries take seconds to get to the Tier I threshold, while discharged batteries could take tens of minutes. The present invention lowers the system voltage before the risk of overcharging and damage occurs, thus achieving the goal of reaching Tier I threshold by charging the battery as fast as possible without overcharging. This feature also helps to break up sulfation on the battery's plates.
The '541 invention controller keeps the battery at the first threshold for a software-determined length of time depending on the battery state-of-charge (from multiple seconds to minutes).
The smart regulator will then regulate the battery's voltage to a second threshold (Tier II). Tier II is in the voltage range of normal voltage regulators (14-15 volts). The regulator keeps the battery at Tier II for a period to ensure that the battery is fully charged, following which the controller tapers back the battery's voltage to a final threshold, or safe-float voltage. This increases fuel economy, battery life, alternator life, and halogen light life. The float voltage is in the range of 13.5 to 14.2 volts, which is the range similar to over-the-road trucks that spend the vast majority of their time running, and not starting.
Application of the '541 invention may i
Haugen Law Firm PLLP
Luk Lawrence
Mixon, Inc.
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