Method and apparatus for preventing electrolysis on battery contacts in a dual-contact battery system

A dual-contact battery pack comprises a housing, a plurality of battery cells located within the housing, a first set of contacts and a second set of contacts coupled to the housing and to the plurality of battery cells. The dual-contact battery further comprises a first control circuit coupled between the plurality of battery cells and the first set of contacts and a second control circuit coupled between the plurality of battery cells and the second set of contacts. The first and second sets of contacts enable the dual-contact battery pack to selectively switch from a first state which prevents current from flowing from the plurality of battery cells to the respective first and second set of contacts to a second state in which current flows from the plurality of battery cells to the respective first and second set of contacts in response to the respective first and second control circuits.

FIELD OF THE DISCLOSURE

The present disclosure relates generally to dual-contact battery systems and more specifically to a dual-contact battery system and method for preventing electrolysis on the battery contacts of the dual-contact battery system.

BACKGROUND

Due to rapid advances in technology, there is an ever increasing number of different portable communication devices used in a variety of environmental conditions. Since most portable communication devices typically use a battery pack for operation, the number of battery packs that are manufactured must be the same as the number of portable communication devices. In order to reduce the need for many battery packs and further to improve logistics, a single battery pack with two contact sets can be used to support two different portable communication devices with different radio contact locations. The use of the battery pack with two contact sets also reduces the number of battery packs to half, thereby improving logistics. However, in such battery packs, the power is present at both the contact sets of the battery packs even when the contact sets are not engaged with the portable communication device. In such cases, if the contact sets that are not engaged with the portable communication devices become exposed to ionic liquids, there exists a possibility of corrosion resulting from electrolysis on these unused contact sets of the battery packs. Electrolysis is a process of accelerated corrosion resulting from an electric current within a metal in an electrolytic environment.

One approach to prevent electrolysis on the unused contact set is to provide water sealing for the exposed unused contact set. However, the water sealing approach uses physical mechanisms to cover the exposed unused contact set causing the battery contact set to cover a large area of the portable communication device thus increasing the size of the portable communication device. Therefore, there exists a need for preventing electrolysis at the unused contact set of the battery pack that does not require the use of any physical mechanism to cover the unused contact sets.

DETAILED DESCRIPTION

Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of method, steps and components related to preventing electrolysis on battery contacts in a dual-contact battery system having a dual-contact battery pack. The dual-contact battery pack comprises a housing, a plurality of battery cells located within the housing, a first set of contacts coupled to the housing and to the plurality of battery cells, and a second set of contacts coupled to a different location on the housing and to the plurality of battery cells. The dual-contact battery pack further comprises a first control circuit coupled between the plurality of battery cells and the first set of contacts and a second control circuit coupled between the plurality of battery cells and the second set of contacts. The first and second sets of contacts enable the dual-contact battery pack to selectively switch from a first state which prevents current from flowing from the plurality of battery cells to the respective first and second set of contacts to a second state in which current flows from the plurality of battery cells to the respective first and second set of contacts in response to the respective first and second control circuits.

In the description herein, numerous specific examples are given to provide a thorough understanding of various embodiments of the invention. The examples are included for illustrative purpose only and are not intended to be exhaustive or to limit the invention in any way. It should be noted that various equivalent modifications are possible within the spirit and scope of the present invention. One skilled in the relevant art will recognize, however, that an embodiment of the invention can be practiced with or without the apparatuses, systems, assemblies, methods, components mentioned in the description.

FIG. 1shows a dual-contact battery system100having a dual-contact battery pack175for coupling to portable electronic devices125and150in accordance with some embodiments. Portable electronic devices125and150may comprise for example, a portable radio, a portable computer, or any other transportable electronic device powered from a rechargeable battery. For the purposes of this application, the dual-contact battery pack175for powering portable electronic devices125and150will be described in terms of portable radios130and155respectively having electronics enclosed therein. Portable radios130and155will sometimes be shown and/or described as Radio A and Radio B respectively. In accordance with one embodiment, each of the portable radios130and155comprises an antenna (represented as135and160inFIG. 1) and a controller section (not shown). The controller section of each of the portable radios130and155includes a microprocessor and may further include a memory device which contains data capable of being accessed. The memory device is preprogrammed by the manufacturer to include a number of different operating parameters and/or operating characteristics for the overall operation of the portable radios130and155.

The dual-contact battery pack175is removably coupled to the portable radios130and155. Two sets of contacts180and185of the dual-contact battery pack175provide power to two different portable radios130and155. The two sets of contacts180and185in the dual-contact battery pack175provide electrical contact with corresponding radio contacts145and170of the portable radios130and155respectively.

Each of the portable radios130and155includes a housing (140,165) for the dual-contact battery pack175in order to facilitate coupling of the dual-contact battery pack175with each of the portable radios130and155. As shown inFIG. 1, the portable radio130includes a housing140for the dual-contact battery pack175and the portable radio155includes a housing165for the dual-contact battery pack175. The housing for each of the portable radios130and155includes a set of radio contacts145and170that engages with the corresponding set of contacts180and185on the dual-contact battery back175to receive power. In particular, the housing140of the portable radio130includes a set of radio contacts145that engages with and receives power from the corresponding first set of contacts180of the dual-contact battery pack175. Similarly, the housing165of the portable radio155includes a set of radio contacts170that engages with and receives power from the corresponding second set of contacts185of the dual-contact battery pack175. In accordance with some embodiments, the location of the set of radio contacts145within the housing140of the portable radio130is different from the location of the set of radio contacts170within the housing165of the portable radio155. The set of radio contacts145of the portable radio130and the set of radio contacts170of the portable radio155include a positive contact, a data contact, a select interface contact, and a negative contact. In accordance with some embodiments, the select interface contact and the negative contact of each of the portable radios130and155are set to ground (not shown).

FIG. 2shows a magnified view of the two sets of contacts180and185in the dual-contact battery pack175. The two sets of contacts180and185are disposed on a housing190of the dual-contact battery pack175for providing power to two portable radios130and155respectively. In accordance with some embodiments, the first set of contacts180and the second set of contacts185are positioned on different locations of the housing190of the dual-contact battery pack175. The first set of contacts180includes four contacts namely a negative contact181, a select interface contact182, a data contact183, and a positive contact184for providing electrical contact with corresponding radio contacts145of the portable radio130. Similarly, the second set of contacts185includes four contacts namely a negative contact186, a select interface contact187, a data contact188, and a positive contact189for providing electrical contact with corresponding radio contacts170of the portable radio155. Electrical and mechanical coupling occur upon the battery pack's first set of contacts180engaging with the portable radio130; and the battery pack's second set of contacts185engaging with the portable radio155respectively.

The negative contact181and the positive contact184of the first set of contacts180of the dual-contact battery pack175channel power to the portable radio130via the negative contact and the positive contact of the portable radio130. Similarly, the negative contact186and the positive contact189of the second set of contacts185of the dual-contact battery pack175channel power to the portable radio155via the negative contact and the positive contact of the portable radio155. Further, the data contact183of the dual-contact battery pack175establishes data communication between the dual-contact battery pack175and the portable radio130via the data contact of the portable radio130. Similarly, the data contact188of the dual-contact battery pack175establishes data communication between the dual-contact battery pack175and the portable radio155via the data contact of the portable radio155.

In accordance with an embodiment, when the select interface contact182engages with the select interface contact of the portable radio130that is set to ground, the select interface contact182of the dual-contact battery pack175also becomes grounded thereby allowing power to appear at the positive contact184of the dual-contact battery pack175. Similarly, when the select interface contact187engages with the select interface contact of the portable radio155that is set to ground, the select interface contact187of the dual-contact battery pack175also becomes grounded, thereby allowing power to appear at the positive contact189of the dual-contact battery pack175.

FIGS. 3A and 3Bshow block diagrams of a first portion and a second portion, respectively of the dual-contact battery pack175in accordance with some embodiments. The first portion of the dual-contact battery pack175(as shown inFIG. 3A) includes a plurality of battery cells200having battery terminals (not shown), such as Nickel, Nickel-Cadmium, or Lithium ion chemistries to name a few. In accordance with one embodiment, the dual-contact battery pack175using Lithium ion cells (two 3.7V nominal voltage cells) are connected in series to provide 7.4V DC nominal voltage. Alternatively, nickel (Ni) based batteries (six 1.2V nominal voltage cells) could also be used. Further, cells are connected in parallel in order to increase the capacity of battery cells200.

Referring toFIG. 3A, the first portion of the dual-contact battery pack175further includes charging interconnect terminals (namely205,210,215, and220) for coupling the dual-contact battery pack175to a charger. The charging interconnect terminals includes positive charge terminal (CH+)210, thermistor terminal (TH)220, charge data (CH data) terminal205, and negative charge terminal (CH−)215. The thermistor terminal (TH)220is coupled to a thermistor305which is further connected to ground. The thermistor305senses the temperature of the plurality of battery cells200and feedbacks the respective voltages to the charger such that the charging of the plurality of battery cells200is controlled between the temperature of zero (0) degrees Celsius to forty five (45) degrees Celsius. The dual-contact battery pack175includes a balun300coupled to the positive charge terminal (CH+)210and the negative charge terminal (CH−)215. The balun300blocks stray radio frequency (RF) energy from the internal dual-contact battery pack175to the charging interconnect terminals on the housing190of the dual-contact battery pack175. The use of balun300ensures that a user's palm while handling any of the portable radios130and155connected to the dual-contact battery pack175is protected from the RF energy of the dual-contact battery pack175. The balun300is coupled to a fuse225for excess charge current protection. The fuse225is selected with a predetermined rating, such as for example a three ampere (3 A) slow blow fuse. The purpose of the fuse225is to protect the plurality of battery cells200from over charging in case a non-compatible battery charger is used to charge the dual-contact battery pack175. The fuse225is coupled to a field effect transistor (FET)230that acts as a primary overvoltage (POV) protection device. The POV protection FET230is further coupled to dual-discharge blocking FETs235and240and a cell protection circuit295. The FETs235and240are used to prevent current from flowing out of the plurality of battery cells200to the positive charge terminal (CH+)210and the negative charge terminal (CH−)215, thereby providing short circuit protection at the charging interconnect terminals.

Referring toFIG. 3B, the second portion of the dual-contact battery pack175includes two sets of contacts180and185, two control circuitries represented as255and260, and a data circuit195formed in accordance with some embodiments. In accordance with some embodiments, the two control circuitries255and260are coupled between the plurality of battery cells200(shown inFIG. 3A) and the two sets of contacts180and185. Specifically, the first control circuit255is coupled between the plurality of battery cells200and the first set of contacts180via the battery terminals. Similarly, the second control circuit260is coupled between the plurality of battery cells200and the second set of contacts185via the battery terminals. The two sets of contacts180and185are either enabled or disabled in response to input received from the corresponding portable radio130and155over the corresponding select interface contacts182and187of the dual-contact battery pack175.

In accordance with some embodiments, as shown inFIG. 3B, the dual-contact battery pack175comprises an over discharge protection control circuit290coupled to the first control circuit255and the second control circuit260. The over discharge protection control circuit290prevents the flow of current from the plurality of battery cells200(shown inFIG. 3A) to the charger when the charger is turned off. In operation, when the dual-contact battery pack175is connected to the charger and the charger is accidently turned on, an over discharge of the plurality of battery cells200might occur. Thus, in order to prevent the over discharge of the plurality of battery cells200, the over discharge protection control circuit290is included in the dual-contact battery pack175.

Further, a data switch250(shown inFIG. 3A) is coupled between the charge data terminal205and the data circuit195(shown inFIG. 3B) which is further connected to the data contacts183and188of the dual-contact battery pack175. The thermistor terminal (TH)220is also coupled to a data switch250. The data switch250establishes a data communication between the charger and the dual-contact battery pack175when the dual-contact battery pack175is connected to the charger. The data switch250further establishes a data communication between the dual-contact battery pack175and an electronic device when the electronic device is connected to the dual-contact battery pack175. Since the dual-contact battery pack175includes two sets of contacts180and185(shown inFIG. 3B), the data circuit195switches the data communication from the data contact183of the first set of contacts180to the data contact188of the second set of contacts185when the second set of contacts185engages with the portable radio155. Similarly, the data circuit195switches the data communication from the data contact188of the second set of contacts185to the data contact183of the first set of contacts180when the first set of contacts180engages with the portable radio130. In accordance with some embodiments, the data circuit195is switched by default to the data contact188side of the second set of contacts185.

The data switch250is also connected to a fuel gauge and memory circuitry285. The fuel gauge and memory circuitry285is further coupled to the plurality of battery cells200through a sense resistor320, an over current (OC) scaling resistor315, and a RF bead310. The RF bead310coupled to the plurality of battery cells200blocks any stray noise at the plurality of battery cells200from appearing at the sense resistor320and the OC scaling resistor315. The RF bead310is further connected to the OC scaling resistor315that provides tight over discharge current range. The sense resistor320connected to the OC scaling resistor315helps in measuring tight tolerance voltage and current value so as to obtain an accurate result from the fuel gauge and memory circuitry285.

The fuel gauge and memory circuitry285monitors a voltage drop across the sense resistor320connected in series with the plurality of battery cells200to determine charging, discharging fuel gauging activity of the plurality of battery cells200. The sense resistor320is further coupled to the cell protection circuit295to prevent the plurality of battery cells200from fault conditions. The cell protection circuit295further includes an over discharge current circuit, an over voltage protection circuit, and an under voltage protection circuit (not shown). The over discharge current circuit terminates an excessive flow of discharge current from the dual-contact battery pack175when the first set of contact180and the second set of contacts185are short circuited beyond a predetermined current value. The over voltage protection circuit prevents charging of the plurality of the battery cells200when any cell from the plurality of the battery cells200exceeds a predetermined over voltage value. Similarly, the under voltage protection circuit is used to prevent discharging of the plurality of the battery cells200when any cell of the plurality of the battery cells200falls below a predetermined under voltage value.

FIG. 4shows a more detailed circuit diagram of the first control circuit255along with the first set of contacts180and the second control circuit260along with the second set of contacts185. The interoperation of a P-channel FET270of the first control circuit255and a P-channel FET280of the second control circuit260are discussed with reference to bothFIGS. 3B and 4.

Referring toFIG. 4, the first control circuit255coupled between the data circuit195and the select interface contact182includes an N-channel field effect transistor (FET)265and a P-channel FET270. The first control circuit255is further coupled to the positive contact184of the first set of contacts180via the P-channel FET270. Similarly, the second control circuit260is coupled between the data circuit195and the select interface contact187of the second set of contacts185. The second control circuit includes an N-channel field effect transistor (FET)275and a P-channel FET280. The second control circuit260is further coupled to the positive contact189of the second set of contacts185via the P-channel FET280. Each of the P-channel FET270, P-channel FET280, N-channel FET265, and N-channel FET275comprises a source terminal (S), a gate terminal (G), and a drain terminal (D). In accordance with some embodiments, the source terminal (S) of the P-channel FET270is coupled to the plurality of the battery cells200, the drain terminal (D) of the P-channel FET270is coupled to the positive contact184of the first set of contacts180, and the gate terminal (G) of the P-channel FET270is coupled to the select interface contact182of the first set of contacts180of the dual-contact battery pack175. Similarly, the source terminal (S) of the P-channel FET280is coupled to the plurality of the battery cells200, the drain terminal (D) of the P-channel FET280is coupled to the positive contact189of the second set of contacts185, and the gate terminal (G) of the P-channel FET280is coupled to the select interface contact187of the second set of contacts185of the dual-contact battery pack175.

In accordance with some embodiments, the dual-contact battery pack175is initially set to an OFF state. The OFF state of the dual-contact battery pack175represents a state in which neither portable radio130nor portable radio155is connected to the dual-contact battery pack175. In such a case, the drain terminal (D) of the N-channel FET265in the first control circuit255and the N-channel FET275in the second control circuit260remains high. The high drain terminal (D) of the N-channel FET265and the N-channel FET275maintains the P-channel FET270and the P-channel FET280respectively in the OFF state. The OFF state of the P-channel FET270and the P-channel FET280ensures that no power appears on the first set of contacts180and the second set of contacts185respectively. Moreover, in accordance with some embodiments, in the OFF state, the data circuit195would switch the data by default to the data contact188of the second set of contacts185of the dual-contact battery pack175and no data is sent to the data contact183of the first set of contacts180.

In accordance with some embodiments, when the portable radio130engages with the first set of the contacts180of the dual-contact battery pack175, the select interface contact182is grounded due to its engagement with the grounded select interface contact of the portable radio130. The grounding of the select interface contact182of the first set of contacts180turns the gate terminal (G) of the P-channel FET270to low, thereby switching ON the P-channel FET270in the first control circuit255. The P-channel FET270when in the ON state closes its power path, thereby channeling power to the positive contact184of the first set of contacts180. Also, as the drain terminal (D) of the N-channel FET265is pulled low, the data circuit switches the data from the data contact188of the second set of contacts185to the data contact183of the first set of contacts180, hence establishing data communication between the dual-contact battery pack175and the portable radio130. The first set of contacts180is thus switched from the OFF state in which no power appears at the first set of contacts180to an ON state in which power appears at the first set of contacts180of the dual-contact battery pack175. In such a case, when the portable radio130is connected to the first set of contacts180, no power appears on the positive contacts189of the second set of contacts185as the gate terminal (G) of the P-channel FET280in the second control circuit260is still tied to high, thereby opening its power path. Accordingly, the electrolysis is prevented on the second set of contacts185of the dual-contact battery pack175by not allowing the power to appear at the second set of contacts185. In other words, the first set of contacts180enable the dual-contact battery pack175to selectively switch from the OFF state which prevents current from flowing from the plurality of battery cells200to the first set of contacts180to the ON state in which current flows from the plurality of battery cells200to the first set of contacts180in response to the first control circuit255.

In accordance with some embodiments, when the portable radio130disengages with the first set of contacts180of the dual-contact battery pack175, the gate terminal (G) of the P-channel FET270is turned high, thereby switching OFF the P-channel FET270. The P-channel FET270in the OFF state prevents power to appear at the first set of contacts180of the dual-contact battery pack175. In such cases, when the portable radio130disengages with the first set of contacts180of the dual-contact battery pack175, the dual-contact battery pack175switches back to the OFF state.

Further, when the portable radio155engages with the second set of the contacts185of the dual-contact battery pack175, the select interface contact187is grounded due to its engagement with the grounded select interface contact of the portable radio155. The grounding of the select interface contact187of the second set of contacts185turns the gate terminal (G) of the P-channel FET280to low, thereby switching ON the P-channel FET280in the second control circuit260. The P-channel FET280closes its power path in the ON state, thereby channeling power to the positive contact189of the second set of contacts185. Also, as the drain terminal (D) of the N-channel FET275is pulled low, the data circuit switches the data from the data contact183of the first set of contacts180to the data contact188of the second set of contacts185, hence establishing data communication between the dual-contact battery pack175and the portable radio155. The first set of contacts180is thus switched from the OFF state in which no power appears at the first set of contacts180to an ON state in which power appears at the first set of contacts180of the dual-contact battery pack175. In such a case, when the portable radio155is connected to the second set of contacts185, no power appears on the positive contacts184of the first set of contacts180as the gate terminal (G) of the P-channel FET270in the second control circuit260is still tied to high, thereby opening its power path. Accordingly, electrolysis is prevented on the first set of contacts180of the dual-contact battery pack175by not allowing the power to appear at the first set of contacts180. In other words, the second set of contacts185enable the dual-contact battery pack175to selectively switch from the OFF state which prevents current from flowing from the plurality of battery cells200to the second set of contacts185to the ON state in which current flows from the plurality of battery cells200to the second set of contacts185in response to the second control circuit260.

In accordance with some embodiments, when the portable radio155disengages with the second set of contacts185of the dual-contact battery pack175, the gate terminal (G) of the P-channel FET280is turned high, thereby switching OFF the P-channel FET280. The P-channel FET280in the OFF state prevents power to appear at the second set of contacts185of the dual-contact battery pack175. In such cases, when the portable radio155disengages with the second set of contacts185of the dual-contact battery pack175, the dual-contact battery pack175switches back to the OFF state.

In accordance with some embodiments, when the dual-contact battery pack175is connected to the charger, the portable radios130and155would still be powered ON as usual. However, if there is no portable radio connected to the dual-contact battery during charging, then there would be no power on the first set of contacts180and the second set of contacts185of the dual-contact battery pack175. Further, when the dual-contact battery pack175is connected to the charger, the data switch250would switch the data from the data circuit195side to the charger side.

InFIG. 5, a flowchart500showing a sequence to prevent electrolysis in the dual-contact battery pack175accordance with some embodiments is shown. In505, both the first and the second set of contacts180and185of the dual-contact battery pack175are in a default state (OFF state) when neither portable radio130(Radio A) nor155(Radio B) is connected to the dual-contact battery pack175. As described with reference toFIG. 3, the default state (OFF state) represents the state in which the P-channel FETs270and280are in the OFF state. In default state of the dual-contact battery pack175, no power appears either at the first set of contacts or at the second set of contacts.

In510, the dual-contact battery pack175detects whether the portable radio130(Radio A) is connected to the first set of contacts180. When the dual-contact battery pack175detects that the portable radio130is connected to the first set of contacts180, the dual-contact battery pack175maintains the second set of contacts185in the default state at515and allows the power to appear at the first set of contacts180in520. Returning back to510, when the dual-contact battery pack175detects that the portable radio130is not connected to the first set of contacts180, the dual-contact battery pack175maintains the default state of505on both sets of contacts180,185until the portable radio130is connected to the dual-contact battery pack175. In accordance with some embodiments, the select contact and the negative contact of the portable radio130are set to the ground. The detection of the engagement of the portable radio130with the dual-contact battery pack175is detected when the select interface contact182engages with the grounded select interface contact of the portable radio130. After the detection of the engagement of the portable radio130with the first set of contacts180of the dual-contact battery pack175, the dual-contact battery pack175enables the power to appear at the first set of contacts180thus powering the engaged portable radio130. In accordance with some embodiments, the select interface contact182of the first set of contacts180, when grounded, switches ON the P-channel FET270(as shown inFIGS. 3B and 4) coupled to the positive contact184of the first set of the contacts180of the dual-contact battery pack. The P-channel FET270, when in ON state, allows power to flow from the plurality of battery cells200to the positive contact184of the first set of contacts180of the dual-contact battery pack175. Further, in525, the data connection is also established between the dual-contact battery pack175and the portable radio130. In accordance with some embodiment, the select interface contact182of the first set of contacts180, when set to ground, switches the data to data contact183side by pulling the drain terminal (D) of N-channel FET275(shown inFIG. 4) to low.

In530, the dual-contact battery pack175detects whether the portable radio155(Radio B) is connected to the second set of contacts185. When the dual-contact battery pack175detects that the portable radio155is connected to the second set of contacts180, the dual-contact battery pack175maintains the first set of contacts180in the default state at535and allows the power to appear at the second set of contacts185in540. Returning back to530, when the dual-contact battery pack175detects that the portable radio155is not connected to the second set of contacts180, the dual-contact battery pack175maintains the default state of505on both sets of contacts180,185until the portable radio155is connected to the dual-contact battery pack175. In accordance with some embodiments, the select contact and the negative contact of the portable radio155are set to the ground. The detection of the engagement of the portable radio155with the dual-contact battery pack175is detected when the select interface contact187engages with the grounded select interface contact of the portable radio155. After the detection of the engagement of the portable radio155with the second set of contacts185of the dual-contact battery pack175, the dual-contact battery pack175enables the power to appear at the second set of contacts185thus powering the engaged portable radio155. In accordance with some embodiments, the select interface contact187of the second set of contacts185, when grounded, switches ON the P-channel FET280(as shown inFIGS. 3B and 4) coupled to the positive contact189of the second set of the contacts185of the dual-contact battery pack175. The P-channel FET280, when in ON state, allows power to flow from the plurality of battery cells200to the positive contact189of the second set of contacts185of the dual-contact battery pack175. Further, in545, the data connection is also established between the dual-contact battery pack175and the portable radio155. In accordance with some embodiment, the select interface contact187of the second set of contacts185, when set to ground, switches the data to data contact188side by pulling the drain terminal (D) of N-channel FET275(shown inFIG. 4) to low.

FIG. 6shows two state diagrams600and650representing the different states of the first set of contacts180and the second set of contacts185respectively of the dual-contact battery pack175. The state diagram600shows two different states605and610of the first set of contacts180. The first state605of the first set of contacts180represent a default state of the first set of contacts180. The default state of the dual-contact battery pack175represents the state in which no power appears at the first set of contacts180of the dual-contact battery pack175. In the default state, the portable radio130is not connected to the first set of contacts180of the dual-contact battery pack175. The first set of contacts180are initially in its first state605and remains in the default state until the portable radio130is connected to the first set of contacts180. When the portable radio130engages with the first set of contacts180of the dual-contact battery pack175, the first set of contacts switches from the first state605to a second state610. The second state610represents the state in which the power appears on the first set of contacts180of the dual-contact battery pack175. The first set of contacts180remains in the second state610until the portable radio130is disconnected from the dual-contact battery pack175. In accordance with some embodiments, when the portable radio130disengages with the first set of contacts180of the dual-contact battery pack175, the first set of contacts180switches from the second state610in which the power appears at the first set of the contacts180to the first state605in which no power appears at the first set of contacts180.

The state diagram650shows two different states655and660of the second set of contacts185. The first state655of the second set of contacts185represent the default state of the second set of contacts185. The default state of the dual-contact battery pack represents the state in which no power appears at the second set of contacts185of the dual-contact battery pack175. In the default state, the portable radio155is not connected to the second set of contacts185of the dual-contact battery pack175. The second set of contacts185is initially in its first state655and remains in the default state until the portable radio155is connected to the second set of contacts185. When the portable radio155engages with the second set of contacts185of the dual-contact battery pack175, the second set of contacts185switches from the first state655to a second state660. The second state660represents the state in which the power appears on the second set of contacts185of the dual-contact battery pack175. The second set of contacts185remains in the second state660until the portable radio155is disconnected from the dual-contact battery pack175. In accordance with some embodiments, when the portable radio155disengages with the second set of contacts185of the dual-contact battery pack175, the second set of contacts185switches from the second state660in which the power appears at the second set of the contacts185to the first state655in which no power appears at the second set of contacts180.

The additional control circuits formed and operating in accordance with the various embodiments prevent corrosion on the unused battery pack contacts even when the contacts are left exposed. The prevention of electrolysis has been achieved without the use of external mechanical piece parts. Thus, the damage caused to the battery contacts as a result of corrosion can now be prevented by using a dual-contact battery system formed and operating in accordance with various embodiments of this invention.

It will be appreciated that some embodiments may be comprised of one or more generic or specialized controllers (or “controlling devices”) such as microcontroller, customized controllers and unique stored program instructions (including both software and firmware) that control the one or more controllers to implement, in conjunction with certain non-controller circuits, some, most, or all of the functions of the method and/or apparatus described herein. Alternatively, some or all functions could be implemented by a state machine that has no stored program instructions, or in one or more application specific integrated circuits (ASICs), in which each function or some combinations of certain of the functions are implemented as custom logic. Of course, a combination of the two approaches could be used.

Those skilled in the art will appreciate that the above recognized advantages and other advantages described herein are merely exemplary and are not meant to be a complete rendering of all of the advantages of the various embodiments of the present invention.