US 20050151505 A1
A battery charger obtains parameter values derived from communication from a battery pack being charged. The battery pack has at least one rechargeable cell, a semiconductor device that stores the charging parameters for the rechargeable cell and communication bus configured to communicate with a battery charger device. The battery pack may have an identification number. A lack of communication between the battery pack and a charger may invoke a default charging program or denial of access to the charger.
1. A rechargeable battery pack comprising:
at least on rechargeable batter cell;
at least one sensor selected from the group consisting of a temperature sensor, a current sensor and a voltage sensor, or combination thereof, capable of generating dynamic data concerning said rechargeable battery pack;
a semiconductor memory affixed to said rechargeable battery pack capable of storing a plurality of data bits indicative of at least one charging parameter of said rechargeable battery pack and a digital representation of said generated dynamic data concerning said rechargeable battery pack;
a communication bus configured to transmit at least some of the data bits concerning said rechargeable battery pack that are stored within the semiconductor memory.
2. The rechargeable battery pack of
3. A rechargeable battery device comprising:
at least one rechargeable battery cell;
sensor means configured to monitor a physical attribute of said at least one rechargeable battery cell;
a digital memory comprising a battery pack ID, and charging parameter values; and
connections for said at least one rechargeable battery cell, said sensor means, and said digital memory to connect to another device.
4. The rechargeable battery device of
5. The rechargeable battery device of
6. A rechargeable battery pack, comprising:
a rechargeable battery cell;
a memory device configured to store charging parameters for said rechargeable battery cell;
connections for said rechargeable battery cell and said memory device to connect to another device.
7. The rechargeable battery pack of
This U.S. patent application is a continuation of U.S. patent application Ser. No. 10/348,584, filed Jan. 21, 2003; which is a continuation of U.S. patent application Ser. No. 09/454,275, filed Dec, 26, 1998, abandoned; which is a continuation of Ser. No. 09/178,675, filed Oct. 26, 1998, issued Jan. 25, 2000 as U.S. Pat. No. 6,018,222; which is a continuation of Ser. No. 08/901,068, filed Jul. 28, 1997, issued Feb. 2, 1999 as U.S. Pat. No. 5,867,006; which is a continuation of Ser. No. 08/764,285, filed Dec. 12, 1996, issued Dec. 2, 1997 as U.S. Pat. No. 5,694,024; which is a continuation of Ser. No. 07/957,571, filed Oct. 7, 1992, issued Jan. 7, 1997 as U.S. Pat. No. 5,592,069.
All of the material in this patent application is subject to copyright protection under the copyright laws of the United States and of other countries. As of the first effective filing date of the present application, this material is protected as unpublished material.
Portions of the material in the specification and drawings of this patent application are also subject to protection under the maskwork registration laws of the United States and of other countries.
However, permission to copy this material is hereby granted to the extent that the owner of the copyright and maskwork rights has no objection to the facsimile reproduction by anyone of the patent document or patent disclosure, as it appears in the United States Patent and Trademark Office patent file or records, but otherwise reserves all copyright and maskwork rights whatsoever.
The present invention relates to electronic devices, and, more particularly, to devices useful for battery charging.
The widespread use of battery-powered portable computers (e.g., notebooks, laptops and palmtops) with high performance relies on efficient battery utilization. In particular, portable computers typically use rechargeable batteries (e.g., lithium, nickel-cadmium, or nickel metal hydride) which weight just a few pounds and deliver 4 to 12 volts. Such batteries provide roughly three hours of computing time, but require about three times as long to be recharged. Such slow recharging is a problem and typically demands that users have several batteries with some recharging while others are being used.
Known battery chargers apply a constant voltage across a discharged battery with the applied voltage determined by the maximum voltage acceptable by the battery.
Furthermore, the different chemistries of various battery types preferably use differing recharging voltages, and varying battery capacities (sizes) demand differing charging currents. However, known battery chargers cannot automatically adapt to such a variety charging conditions and remain simple to use.
The present invention provides battery charging with charging parameter values selected by communication with imbedded information in a battery pack and then adjusted during charging. This permits adaptation to various battery chemistries and capacities, and, in particular, allows for approximately constant current charging at various current levels and for trickle charging.
The present invention will be described with reference to the accompanying drawings, which are schematic for clarity.
Battery charger 200 can provide battery charging up to about 20 volts with 2.5 amp currents; this demands a separate power transistor 202 for cooling. Transistor 202 functions essentially as a current source and is coupled to controller 210 through driver 218. (More generally, power transistor 202 could be replaced by a DC-to-DC converter.) The current source also comprises a current level detector 215. Current level detector 215 comprises resistor 204 and difference amplifier 214 to detect the current level through resistor 204 and into battery pack 250 through output terminal 230 Controller 210 also comprises an analog-to-digital converter to convert the analog current value detected by current level detector 215, which is used to compute the present voltage of the batteries in battery pack 250 through Ohm's law (since the resistance is constant and known). The present voltage is compared to stored values of previous values of the voltages of the batteries in battery pack 250, which were computed using the same method. Battery pack 250 may have various numbers of cells and cells of various chemistries which require various charging programs. Controller 210 acquires information about battery pack 250 through inquiry over the one-wire communication bus 220. In particular, communication module 252 within battery pack 250 contains identification plus charging parameter values, such as maximum voltage VMAX and maximum current IMAX along with charge time and endpoint detection method. Controller 210 reads the identification and charging parameter values and configures itself accordingly. Note that the identification can be used for access control: battery charger 200 can refuse to charge a battery pack with an invalid identification. Controller 210 also has stored (in nonvolatile ROM) default charging parameter values. Thus when controller 210 is unable to read charging parameter values from battery pack 250, it may read from its own ROM for default parameter values. After acquisition of parameter values, battery charger 200 begins charging battery pack 250. Battery charger 200 may also communicate at high speed over a second communication terminal, which is preferably a three-wire bus 223 with a computer or other controller; this permits external analysis of the identification and charging parameter values read from communication module 252 plus external control of access and the charging parameter values.
When power is supplied to charger 200 (PF=0), it first checks the inputs of temperature sensors 206 and 207; controller 210 converts the output of temperature sensors 206 and 207 to digital values, if necessary, using an analog-to-digital converter housed inside controller 210, so that a comparator, which is embedded inside controller 210 can compare the temperature values outputted from temperature sensors 206 and 207. These values are inputted into controller 210 through temperature sensor input terminal 209, first temperature input terminal 209 a and second temperature input terminal 209 b. Temperature along with voltage and current are considered to be measured values, since they are routinely measured by controller 210, and if the battery temperature (TB) is less than the upper temperature limit for trickle charge (T5) and if the ambient temperature TA) is greater than the lower temperature for trickle charge (TO), battery charger 200 moves to an initial trickle charge state of applying a trickle charge current (I3). The circle in the center of
In the one-wire communication state charger 200 maintains the trickle charge current to the connected battery pack 250 (I=I3) and the charging timer remains off (TMRRST=1). Further, battery charger 200 sends a reset signal over the one-wire communication bus 220 to initiate a read (1 WIRE RD) of the identification and charging parameter values in communication module 252 of battery pack 250. Battery charger 200 either reads a recognizable identification to permit charging or not. When an acceptable identification is read but no charging parameter values, communication module 252 reads from its ROM default charging parameter values. Controller 210 loads the charging parameter values into registers to configure its various subcircuits for comparisons of measured charging parameters with the loaded values. If at any time during this one-wire communication power fails or battery pack 250 is disconnected or the ambient temperature falls below the trickle charge minimum or the battery temperature rises above the trickle charge maximum, battery charger 200 reverts to the no power state. Otherwise, after completing the one-wire communication (OWRCMPLT=1), battery charger 200 again checks the ambient and battery temperatures from sensors 206 and 207 and if the battery temperature is less than the upper temperature for rapid charge (T3) and if the ambient temperature is greater than the lower temperature for rapid charge (T2), then battery charger 200 switches to a state of rapid charge represented by the circle in the lefthand center of
In the rapid charge state controller 210 drives the charging current up to I1 and starts the charging timer (I=I1 and TMRRST=0). If there is a power failure or battery pack 250 is disconnected, then battery charger 200 again reverts to the no power state; otherwise, the rapid charge state persists and battery charger 200 supplies a charging current I1 to battery pack 250 until one of the following occurs: (1) the battery voltage parameter (VBAT) measured at voltage sense node 205 exceeds the parameter value (VBATLIM) read from communication module 252, (2) the parameter battery voltage delta (peak battery voltage sensed at voltage sense node 205 so far during the charging minus the battery voltage now sensed) (DELV) exceeds the parameter value (DELVLIM) read from communication module 252 and the charging timer has been running for more than 5 minutes, (3) the charging timer has been running longer than the time for rapid charge parameter value (t0LIM) read from battery module 252, (4) the ambient temperature is below parameter value T2, (5) the battery temperature is above parameter value T3, or (6) the battery temperature delta (equal to TB-TA) (DELT) exceeds the parameter value (DELTLIM) read from communication module 252. When one of these six events occurs, battery charger 200 moves to the standard charge state represented by the circle in the lower lefthand portion of
In the standard charge state controller 210 drives the charging current to I2 and restarts the charging timer (I=I2) and TMRRST=0). If there is a power failure or battery pack 250 is disconnected, then battery charger 200 again reverts to the no power state; otherwise, the standard charge state persists and battery charger 200 supplies a charging current I2 to battery pack 250 until one of the following events occurs: (1) the battery voltage (VBAT) sensed at voltage sense node 205 exceeds the maximum battery voltage during charge (VBATLIM), (2) the charging timer has been running longer than the maximum time for standard charge (t1LIM), (3) the ambient temperature is below the lower temperature limit for standard charge (T1), or (4) the battery temperature is above the upper temperature limit for standard charge (T4). When one of these four events occurs, battery charger 200 moves to the trickle charge state represented by the circle in the lower center of
In the trickle charge state controller 210 drives the charging current back to I3 and stops the charging timer (I=I3 and TMRRST=1). If there is a power failure or battery pack 250 is disconnected or the battery voltage VBAT exceeds the maximum VBATLIM, then battery charger 200 once again reverts to the no power state; otherwise, the trickle charge state persists and battery charger 200 supplies a charging current I3 to battery pack 250 until either (1) the ambient temperature is below TO or (2) the battery temperature is above T5. When one of these two events occurs, battery charger 200 moves to the standby state represented by the circle in the lower righthand portion of
In the standby state controller 210 turns off power transistor 202 and stops the charging timer (I=I3 and TMRRST=1). If there is a power failure or battery pack 250 is disconnected, then battery charger 200 once again reverts to the no power state; otherwise, the standby state persists with battery charger 200 not supply any charging current I3 to battery pack 250 until either (1) the ambient temperature is rises above TO or (2) the battery temperature falls below T5. When one of these two events occurs, battery charger 200 returns to the trickle charge state from whence it came and repeats itself.
The flow shown of
Once battery pack 250 has been detected, controller 210 applies a reset signal on the data line of one-wire communication bus 220 by driving the data line low (ground) for about 480 microseconds (μs) and then pulling the data line high (+5 volts) for about 480 μs. In response to the 480 μs low reset signal, communication module 252 signals its presence with a presence detect signal by pulling the data line low during the 480 μs high. The pulldown in communication module 252 overpowers the pullup of controller 210, so the data line goes low and controller 210 senses the low. Communication module 252 generates a nominal 120μs time period for the pulldown presence detect pulse and applies this pulldown beginning a nominal 30 μs after controller 210 has returned the data line high. However, this time period may vary by a factor of 2 amongst communication modules, so controller 210 samples the data line at 65-70 μs after it has returned the data line high. See
If the sampling of the data line by controller 210 does not reveal a presence detect signal (Reconfigurable=1 not true in
Communication module 252 has two memories: a 64-bit ROM for identification and a 256-bit EEPROM for charging parameter values.
After reading the ROM of communication module 252, controller 210 then reads the 256 bits of EEPROM to get charging parameter values for operation (Read Config Data Into Charger Config RAM). The reading of the parameter values is also checked by a CRC byte (Verify RAM CRC). Once the EEPROM has been read, the one-wire communication is complete (One Wire Read Complete in
U.S. Pat. No. 5,045,675 contains a discussion of one-wire communication and serial memory reading and is hereby incorporated by reference.
Further Modifications and Variations
The preferred embodiments may be modified in many ways while retaining one of more of the features of a battery charger with charging parameter values selected by communication with a battery pack to be charged and using multiple constant charging currents with multiple endpoint determinants. For example, the memory in the battery pack could be all ROM or all EEPROM, or EPROM, a mixture of two memory types; the communication could be over full duplex or other than one-wire, and the memory may have its own power supply to be operative with a discharged battery pack; sensors for endpoint determinants other than temperature increment and voltage increment may be used; the power transistor could be a switching AC-DC converter or a switching DC-DC converter; the controller may have nonvolatile memory orjust registers for holding charging parameter values; and so forth.