Electricity: battery or capacitor charging or discharging – Means to identify cell or battery type
Reexamination Certificate
2001-05-14
2002-06-11
Toatley, Gregory (Department: 2838)
Electricity: battery or capacitor charging or discharging
Means to identify cell or battery type
C320S157000
Reexamination Certificate
active
06404164
ABSTRACT:
TECHNICAL FIELD
This invention relates to battery technology. In particular, the invention relates to identifying battery type from voltage behavior in an electronic device.
BACKGROUND OF THE INVENTION
Electronic devices capable of deriving operating power from one or more batteries are popular, widely available and in widespread use. Many of these electronic devices would be much less successful and even lose much of their market viability without the availability of reliable battery power. In particular, portable electronic devices generally depend on batteries as a primary power source. For example, popular portable electronic devices such as notebook and laptop computers, hand-held computers and personal digital assistants (PDAs), digital cameras, and cellular telephones would be of little or no use without battery power.
Electronic devices that employ batteries can use batteries as either a primary power source or as a secondary power source. In some cases the electronic device is powered entirely by a DC power supply based on a battery. In other cases, the battery powered electronic device can be operated either using battery power or using an external DC or AC power source. Generally, an AC adapter that converts the AC into DC provides the external DC power source for those electronic devices that use external DC power. The external AC/DC power source is also commonly used for recharging batteries in portable electronic devices that utilize in-situ rechargeable battery cells.
In simple terms, a battery is a device that converts chemical energy into electricity. A variety of battery types that have application to powering electronic devices are commercially available. Batteries can be divided into two broad classes depending on whether the battery is rechargeable or non-rechargeable. The distinction between rechargeable and non-rechargeable batteries is often important since attempting to recharge non-rechargeable batteries can lead to venting or leaking of electrochemical materials, and in extreme cases can result in dangerous explosions.
Directly related to whether or not a battery is rechargeable is the particular battery chemistry that is employed. The ‘chemistry’ of the battery refers to the specific combination of electrolytes and electrode materials used in the battery to create the chemical reaction that produces electrical power. Several battery chemistries, some of which produce rechargeable batteries and some of which produce non-rechargeable batteries, are in use and commonly available.
A common battery chemistry used for electronic devices is the well-known alkaline battery. The standard alkaline battery employs an alkaline gel, usually potassium hydroxide, as an electrolyte. The positive electrode is normally made of magnesium dioxide and the negative electrode is typically made of zinc. Other battery chemistries commonly used to power electronic devices include but are not limited to high-drain alkaline, high-energy lithium, nickel-metal hydride (NiMH) and nickel-cadmium (NiCd). Of these, normally only batteries having NiMH or NiCd chemistries are rechargeable while the others are generally not rechargeable. Batteries of different chemistries generally have different electrical properties such as open-circuit voltage, charge capacity, and peak current capacity. These electrical properties are a direct result of the characteristics of the chemical reactions taking place within the batteries. The unique characteristics of a chemical reaction such as rate, reaction path, and reactants involved are sometimes referred to collectively as the reaction's ‘kinetics’.
Consumer batteries are most often classified based on the physical size and shape of the battery and only secondarily on chemistry and rechargeability. The physical size and shape of a battery is sometimes referred to as the ‘form-factor’ of the battery. Many battery chemistries are available in more than one form-factor. More to the point, some of the popular form-factors are available in more than one battery chemistry. Thus, even though different chemistries have different kinetics and rechargeability characteristics, the form-factor of the battery may not reflect any difference between them at all.
Electronic devices are available that utilize batteries having a wide variety of different form-factors. Both standard form-factors and custom form-factors are in common use. Available standard form-factors include but are not limited to AA, AAA, C and D cells. Many of the commercially available consumer battery chemistries can be found in more than one of the standard form-factors. Custom battery form-factors include customized single cells as well as specialized battery packs that contain more than one cell. A battery or battery pack having a customized form-factor is sometimes referred to as an ‘application-specific’ battery. Specialized application-specific battery packs and custom form-factors are most typically associated with battery chemistries that are rechargeable, though non-rechargeable battery types are available in some non-standard form-factors as well.
Most portable electronic devices monitor the battery during use and typically provide a charge level indicator or so-called ‘fuel gauge’ associated with battery life. The fuel gauge is intended to keep the user of the device apprised of the power remaining in the battery and, by extension, the probable remaining operating time of the electronic device. In addition, the fuel gauge is used by the device to determine a cut-off point in the battery discharge profile beyond which the device will cease to operate.
Fuel gauges on portable electronic devices generally attempt to ‘predict’ the power remaining based on measurements, usually voltage measurements, performed on the battery. Unfortunately, the accuracy of these measurements can and usually does depend on battery chemistry. For example, a voltage based fuel gauge calibrated for alkaline batteries will most likely not be accurate for NiMH batteries of the same form factor. Most portable electronic devices that can accept AA size batteries can utilize a variety of battery chemistries that are available in the AA form-factor. Unfortunately, as discussed hereinabove, the different battery chemistries do not behave the same way kinetically during discharge, especially in the presence of a short duration moderately high load. Thus, it is very difficult for conventional fuel gauging techniques to be accurate in high drain devices which can accept multiple battery chemistries and have no way of distinguishing one battery chemistry from another.
Most battery powered electronic products currently on the market use one of two methodologies in conjunction with monitoring batteries and providing fuel gauging. A first methodology known as current or power monitoring, determines the energy capacity remaining in a battery by monitoring the power or current passing into and out of the battery. This methodology requires knowledge of the approximate amount of energy that can be drained from the battery before it is discharged. As such, the use of power/current monitoring is generally restricted to electronic devices that utilize a battery where characteristics such as the battery chemistry and size are known a priori such as an application-specific battery pack. An application-specific battery pack is generally manufactured and distributed under the control of the electronic device manufacturer. Therefore, the manufacturer can impose limits on the battery pack specifications and thus effectively have a great deal of control over the accuracy of the battery monitoring and fuel gauging using the power/current monitoring methodology. Essentially, the fuel gauge can be calibrated accordingly based on the a priori knowledge of the application-specific battery pack performance characteristics.
Because a priori knowledge of battery characteristics is not possible in devices that accept multiple battery brands or chemistries, the power/current monitoring methodology generally is not used for fuel gauging in t
Bean Heather N
Whitman Christopher A.
Woods Scott A
Hewlett--Packard Company
Toatley Gregory
LandOfFree
Method of battery chemistry identification through analysis... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method of battery chemistry identification through analysis..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method of battery chemistry identification through analysis... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2972618