The present invention relates to battery testers and, in particular, to battery testers capable of testing batteries installed in devices without having to gain direct access to the installed batteries.
Over a million battery-powered floor effects (e.g., stomp boxes) have been sold in the electronic and amplified music industry every year for the last 30 years. More and more guitars (both electric and acoustic) have battery-powered preamps. All of these products use the well known rectangular 9 volt battery.
For most of these devices, the battery is installed internally requiring the removal of numerous screws and a cover plate to test and or change the battery. In general, there is no way to know if the battery is good or bad without removing it. As a result, most musicians automatically change the battery once they have gone through the task of opening the compartment whether the battery still has useful life or not. No one wants to have a guitar or processor go dead during a rehearsal or show. Thus, millions of batteries are tossed out prematurely.
According to the present invention, an in-situ battery tester is provided. According to a particular class of embodiments, a battery tester is provided for testing a battery under test installed in a device without requiring direct access to or removal of the battery under test. A stereo plug is configured for insertion into a stereo jack on the device to thereby complete a circuit including the battery under test and a load circuit in the device to which the battery under test supplies power. First circuitry is configured to measure a battery voltage corresponding to the battery under test. Second circuitry is configured to measure a load current corresponding to the load circuit to which the battery under test supplies power. Control circuitry is configured to generate one or more signals representative of remaining battery life for the battery under test with reference to the battery voltage and the load current. A display is configured to generate a representation of the remaining battery life using the one or more signals. According to some embodiments, the representation of the remaining battery life includes one or both of a voltage or a number of hours.
According to a specific embodiment, the battery tester includes two contacts external to its housing and in electrical communication with fourth circuitry. The two contacts and the fourth circuitry are configured for testing of a first type of loose battery connected to the contacts. According to a more specific embodiment, the fourth circuitry is further configured for testing of at least one additional type of loose battery connected to one of the contacts and a tip conductor of the stereo plug.
According to another specific embodiment, the control circuitry includes an analog-to-digital converter having an input range, and the battery tester includes ranging circuitry configured to adapt the battery voltage to the input range of the analog-to-digital converter.
According to still another specific embodiment, the second circuitry employs a sense resistance comprising a combination of one or more of a plurality of sense resistors to measure the load current, and includes selection circuitry configured to select from among the sense resistors for different ranges of a current signal generated by the sense resistance.
According to yet another specific embodiment, the battery tester includes third circuitry configured to select a battery chemistry type. The control circuitry is configured to generate the one or more signals representative of remaining battery life with reference to the selection of battery chemistry type.
According to a further specific embodiment, the stereo plug comprises a first tip conductor, a first ring conductor, and a first sleeve conductor configured to contact a second tip conductor, a second ring conductor, and a second sleeve conductor in the stereo jack, respectively. The stereo plug has a profile that makes it unlikely that the first tip conductor causes a short circuit between the second ring conductor and the second sleeve conductor as the stereo plug is being inserted into the stereo jack.
According to yet another specific embodiment, the control circuitry includes a microcontroller configured to employ a representation of the battery voltage as an index into a lookup table to select a current*time value, and to generate the one or more signals representative of remaining battery life by dividing the current*time value by a representation of the load current. According to a more specific embodiment, the battery tester includes third circuitry configured to select a battery chemistry type, and the lookup table is one of a plurality of lookup tables each of which corresponds to a particular battery chemistry type. The microcontroller is configured to select the lookup table from among the plurality of lookup tables with reference to the battery chemistry type selected.
According to another more specific embodiment, the microcontroller is configured to compensate for reduction of the remaining battery life as a function of increasing current draw. According to yet another more specific embodiment, the microcontroller is configured to compensate for the remaining battery life occurring at a lower battery voltage relative to the measured battery voltage.
According to another class of embodiments, a stereo plug is provided for insertion into a stereo jack. The stereo plug includes a tip conductor, a ring conductor, and a sleeve conductor, and has a profile such that the tip conductor is narrower than a maximum width of the widest portion of the stereo plug, and the ring conductor is also narrower than the maximum width of the stereo plug. The stereo plug includes a first dielectric insulator insulating the tip conductor from the ring conductor, and a second dielectric insulator insulating the ring conductor from the sleeve conductor. A portion of the first dielectric insulator increases in width from the tip conductor to the maximum width and then decreases in width from the maximum width to the ring conductor. A portion of the second dielectric insulator increases in width from the ring conductor to the maximum width.
A further understanding of the nature and advantages of the present invention may be realized by reference to the remaining portions of the specification and the drawings.
Reference will now be made in detail to specific embodiments of the invention including the best modes contemplated by the inventors for carrying out the invention. Examples of these specific embodiments are illustrated in the accompanying drawings. While the invention is described in conjunction with these specific embodiments, it will be understood that it is not intended to limit the invention to the described embodiments. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims. In the following description, specific details are set forth in order to provide a thorough understanding of the present invention. The present invention may be practiced without some or all of these specific details. In addition, well known features may not have been described in detail to avoid unnecessarily obscuring the invention.
The present invention provides a battery tester (specific embodiments of which are referred to herein as the “Batt-O-Meter”) that can measure the life of a battery without requiring direct access to or removal of the battery from the device it is powering. As will be understood with reference to the Background of the Invention, such a battery tester is particularly advantageous for testing batteries installed in musical instruments and related devices, and specific embodiments are described herein with reference to such applications. However, it should be noted and will be understood by those of skill in the art that the basic principles of the present invention are more generally applicable.
According to a particular class of embodiments, a battery tester is provided that has an associated stereo plug (e.g., a conventional ¼″ plug or a modified plug as described below) that may be inserted into the available jack on the instrument or device, e.g., a stomp box. According to specific implementations, once the jack is inserted, the tester's display reports the voltage and, in some implementations, how many hours of life the battery has left to power the device in which it is installed.
During normal operation, the instruments and devices for which some embodiments of the invention are designed sense the insertion of the ¼″ plug to apply power to the components to which the battery under test supplies power. Taking advantage of this standard configuration, the Batt-O-Meter can measure critical information that lets the user know how much longer the battery will work without having to make direct contact to the positive contact of the battery as is usually required. In addition, as will be discussed, embodiments of the Batt-O-Meter may be configured to test any stand-alone battery (9V, AAA, AA, C, D, etc.), as well as other types of cells such as, for example, prismatic or button cells. Embodiments are also contemplated that enable the testing of different battery chemistry types, e.g., alkaline, carbon-zinc, rechargeable (e.g., NiCd, LiPo, or NiMH), etc., with the same battery tester.
For the price of a handful of batteries, embodiments of the present invention provide a sophisticated, accurate, and easy to use battery tester that can save time, money, and possible embarrassment on stage.
As mentioned above, musical effects devices such as stomp boxes and musical instruments typically use a standard ¼″ diameter plug and jack to connect with other equipment. These devices take advantage of the differences between mono (i.e., single conductor and ground) and stereo (i.e., two conductors and ground) plugs and jacks to easily and cheaply turn a device on merely by plugging a mono plug into a stereo jack. This may be understood with reference to
According to a particular implementation illustrated in
As will be described, a particular implementation of the Batt-O-Meter uses a microcontroller-based data acquisition system that reads the battery voltage and measures the current demands of the load circuit of the battery under test. Operation of a particular implementation of the code which governs the operation of the microcontroller may be understood with reference to the discussion below. Such code may be stored in physical memory or any suitable storage medium (not shown) associated with the microcontroller, as software or firmware, as understood by those of skill in the art. However, it should be noted that the use of a microcontroller or similar device is not necessary to implement the invention. Most, if not all, of the functionality described herein may be implemented using alternative technologies without departing from the scope of the invention. For example, embodiments are contemplated which implement such functionalities using programmable or application specific logic devices, e.g., PLDs, FPGAs, ASICs, etc. Alternatively, analog circuits and components may be employed. As yet another alternative, at least some functionality may be implemented using mechanical components. These and other variations, as well as various combinations thereof, are within the knowledge of those of skill in the art, and are therefore within the scope of the present invention.
Referring now to
A current measurement block 308 employs one or more sense resistors applied across the ring and sleeve inputs to the Batt-O-Meter (e.g., ring 356 and sleeve 358). The drop across the sense resistor(s) is proportional to the current that load circuit 354 draws. According to a specific implementation, and as will be discussed, current measurement block 308 is auto ranging using switchable sense resistances (e.g., R ISense Coarse and R ISense Fine). Auto ranging allows for extremely accurate measurements, e.g., from a few micro amps to tens of milliamps, with microcontroller 304 determining the appropriate sense resistor(s) to utilize. Depending on the implementation, more or fewer sense resistors may be used for more or less range. According to some implementations, multiple readings may be taken to guarantee accurate data.
Once the voltage and current are known it is possible, assuming a particular battery chemistry type, to determine the remaining time (e.g., the number of hours) the battery under test will operate in the device in which it is installed. That is, this determination is dependent on the type of chemistry that the battery under test employs. Therefore, according to a specific embodiment, the user may select a particular battery chemistry type via a three-position switch 310 (e.g., a 3 position slide switch implemented as a double-pole, triple-throw (dp3t) switch) for which the different positions correspond to alkaline, carbon-zinc, or rechargeable (e.g., NiCd or NiMH) cells. Embodiments may also support other battery chemistries, including but not limited to various forms of lithium batteries. Microprocessor 304 uses the chemistry information to select a corresponding look up table that includes parameter values for determining the remaining time of operation which is then presented on display 306, in this case a 3-digit LED or LCD display. According to an alternative embodiment, the display is implemented using green, yellow, and red diodes which are selectively activated using the same or equivalent information provided to the 3-digit display to indicate “good,” “fair,” and “poor” charge levels. A variety of other mechanisms for conveying this information are also contemplated.
It should also be noted that embodiments of the invention are contemplated in which the battery chemistry is assumed to be a particular type, i.e., the battery tester is configured only for testing batteries of a particular chemistry type. Thus, mechanisms for specifying the chemistry type of the battery under test are optional.
According to some implementations, and as will be discussed, the Batt-O-Meter may include a self-test mode that checks the battery powering the tester (e.g., internal battery measurement block 312), and/or the cleanliness (e.g., conductivity) of the stereo plug (e.g., plug test block 314) and provides feedback to the user via the display.
According to some implementations, external 9 volt batteries, i.e., batteries not installed in devices, can also be tested using external battery measurement block 316 via contacts external to the Batt-O-Meter (e.g., contacts 204 and 206 of
Referring again to
The results of the poll loop are used to determine the current state of system (406). For example, the system state might be that there is currently no UUT connected to the tester. Alternatively, the system might be determined to be in self-test mode, voltage measurement mode, current measurement mode, external battery test mode, fault condition, etc.
According to a specific embodiment, a single-pole, single-throw tact momentary switch (e.g., switch 318 of
Referring again to
The A/D converter poll loop goes through a sequence of reads, flags, and saves for the A/D channels depending on the particular implementation. As shown in
A current measurement for the UUT is then made, e.g., using current (hours) measurement block 308 of
According to particular implementations, additional corrections related to current draw may be introduced. According to a particular class of embodiments, one such correction compensates for the reduction or de-rating of battery capacity as a function of increasing current draw which occurs in many battery chemistries. This may be achieved, for example, using a small (e.g., 8 entry) piecewise lookup table for each chemistry.
According to another class of embodiments, an implicit impedance correction factor may be built into the battery capacity tables to compensate for the phenomenon that the remainder of the lifecycle occurs at a lower battery voltage relative to that measured at any given moment. To the extent that the load is resistive rather than constant current, the current draw will decrease relative to the presently measured current draw. Experimentation with effects boxes from various manufacturers showed that, on average, the load curve may be modeled as 60% resistive and 40% constant current. This assumption may then be used to pre-distort the battery capacity table(s) relative to a standard constant-current load.
The final, corrected battery capacity value is then used to derive the time remaining (e.g., in hours) using the measured load current (e.g., see 910 of
As a consequence of the impedance correction factor built into the battery capacity table in some embodiments, a reverse correction factor may need to be applied when the tables are used to calculate percent remaining for an external battery (e.g., 370 of
During testing of Batt-O-Meter designs, it was found that the configuration of some devices in which the battery under test was installed was such that a standard stereo plug (e.g., plug 112 of
Like conventional stereo plugs, modified stereo plug 1100 has three conductors, i.e., signal conductors 1102 and 1104, and ground conductor 1106. However, in contrast with conventional stereo plugs (e.g., stereo plug 112 of
The narrowing at ring conductor 1104 prevents bridging to the sleeve contact on the jack during insertion. According to a specific implementation, tip conductor 1102 is a straight 0.080 pin designed to avoid contact with the sleeve or the ring on the jack during insertion. The tapered dielectric at the base of the 0.080 pin prevents the plug from hanging up on certain jacks during insertion. The similar tapers at either edge of the recessed ring conductor 1104 serve a similar purpose.
Other embodiments, included within the scope of the invention, may employ software, electronic, or mechanical mechanisms to counteract the accidental or deliberate (via the current test) charging of UUT bypass or coupling capacitors. These mechanisms may include but are not limited to: fixed voltage settling delay, variable or conditional voltage settling delay, settling time or value prediction such as a Taylor series or other algorithm, or electronic circuitry for discharging or for charge injection.
According to a specific embodiment, and as mentioned above, tip conductor 1102 may be employed to facilitate testing of loose, external batteries, e.g., using external battery measurement block 316 of
In a specific embodiment, the tip is connected to the negative terminal of the external battery (e.g., battery 370 of
While the invention has been particularly shown and described with reference to specific embodiments thereof, it will be understood by those skilled in the art that changes in the form and details of the disclosed embodiments may be made without departing from the spirit or scope of the invention. In addition, although various advantages, aspects, and objects of the present invention have been discussed herein with reference to various embodiments, it will be understood that the scope of the invention should not be limited by reference to such advantages, aspects, and objects. Rather, the scope of the invention should be determined with reference to the appended claims.
The present application claims priority under 35 U.S.C. 119(e) to U.S. Provisional Patent Application No. 61/104,178 entitled BATT-O-METER filed on Oct. 9, 2008 (Attorney Docket No. KSMOP002P), the entire disclosure of which is incorporated herein by reference for all purposes.
Number | Date | Country | |
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61104178 | Oct 2008 | US |