Battery parallel charging technology

Abstract

According to some embodiments, a charging device is provided. A charging device includes (1) a charging circuit configured to be connected in parallel to a plurality of battery packs, and (2) a processing circuit configured to control the charging circuit by: (a) obtaining a voltage reading from each battery pack of the plurality of battery packs; (b) initially setting a charging voltage of the charger to a minimum voltage reading obtained from any one of the plurality of battery packs; (c) obtaining a current reading from each of the plurality of battery packs being charged while applying the charging voltage to the plurality of battery packs; and (d) in response to the current reading obtained from the battery pack being below the minimum threshold current, increasing the charging voltage by a voltage step value. Similar methods and computer program products are also provided.

Description

Background Technology

[0001] An uninterruptible power supply (UPS) unit provides backup power to electrical equipment in the event of a power failure. A UPS unit typically utilizes one or more batteries to provide backup power. Although various types of batteries can be used, lithium-ion (Li-ion) batteries have become more popular in recent years due to their high energy density and long lifespan. Because overcharging, deep discharging, or charging too quickly can damage lithium-ion batteries, lithium-ion battery packs are typically equipped with a battery management system (BMS) to prevent overcharging, deep discharging, and charging with excessively high voltage differentials. Summary of the Invention

[0002] According to some embodiments, a charging device is provided. The charging device includes (1) a charging circuit configured to be connected in parallel to a plurality of battery packs, and (2) a processing circuit configured to control the charging circuit in such a way as to: (a) obtain a voltage reading from each of the plurality of battery packs; (b) initially set the charging voltage of the charger to the lowest voltage reading obtained from any of the plurality of battery packs; (c) obtain a current reading from each of the plurality of battery packs being charged while applying the charging voltage to the plurality of battery packs; and (d) increase the charging voltage by a voltage step value in response to a current reading obtained from a battery pack being lower than a minimum threshold current.

[0003] In one implementation, the processing circuitry is further configured to control the charging circuitry by reducing the charging voltage to less than a voltage step value in response to any of the obtained current readings that are higher than the maximum threshold current.

[0004] In one implementation, the processing circuitry is further configured to control the charging circuitry by reducing the voltage step value in response to any of the obtained current readings that are higher than the maximum threshold current.

[0005] In one embodiment, obtaining a voltage reading from each of the multiple battery packs includes receiving a voltage reading from each of the multiple battery packs, the voltage reading having been sent by the respective battery management system of each of the multiple battery packs.

[0006] In an embodiment, obtaining a current reading from each of the plurality of battery packs being charged includes receiving a current reading from each of the plurality of battery packs being charged, the obtained current reading having been sent by the respective battery management system of each of the plurality of battery packs being charged.

[0007] In some embodiments, the processing circuit is further configured to control the charging circuit in such a way that, in response to detecting that (A) the charging protection switch of at least one of the plurality of battery packs is open and (B) the charging voltage exceeds the voltage of each of the plurality of battery packs by at least a threshold amount, the charging voltage is maintained until the charging protection switch of each of the plurality of battery packs is closed. In one of these embodiments, the threshold amount is 1 volt.

[0008] In one embodiment, the processing circuit is further configured to control the charging circuit by maintaining the charging voltage at the maximum charging voltage threshold in response to detecting that the charging voltage has reached the maximum charging voltage threshold.

[0009] According to some embodiments, a method for charging a plurality of battery packs is provided. The method includes (a) obtaining a voltage reading from each of the plurality of battery packs; (b) initially setting a charging voltage to the lowest voltage reading obtained from any of the plurality of battery packs; (c) obtaining a current reading from each of the plurality of battery packs being charged while applying the charging voltage to the plurality of battery packs; and (d) increasing the charging voltage by a voltage step value in response to a current reading obtained from a battery pack being lower than a minimum threshold current.

[0010] In an embodiment, the method further includes: in response to any of the obtained current readings being higher than a maximum threshold current, reducing the charging voltage to less than a voltage step value.

[0011] In an embodiment, the method further includes: reducing the voltage step value in response to any of the obtained current readings being higher than the maximum threshold current.

[0012] In an embodiment, the method further includes: in response to detecting that (A) the charging protection switch of at least one of the plurality of battery packs is open and (B) the charging voltage exceeds the voltage of each of the plurality of battery packs by at least a threshold amount, maintaining the charging voltage until the charging protection switch of each of the plurality of battery packs is closed.

[0013] According to some embodiments, a computer program product is provided. The computer program product includes a non-transitory computer-readable storage medium storing instructions that, when executed by processing circuitry of a charging device, cause the charging device to charge a plurality of battery packs in parallel by: (a) obtaining a voltage reading from each of the plurality of battery packs; (b) initially setting the charging voltage of the charging device to the lowest voltage reading obtained from any of the plurality of battery packs; (c) obtaining a current reading from each of the plurality of battery packs being charged while applying the charging voltage to the plurality of battery packs; and (d) increasing the charging voltage by a voltage step value in response to a current reading obtained from a battery pack being lower than a minimum threshold current.

[0014] In one embodiment, the instruction, when executed by the processing circuitry, further causes the charging device to reduce the charging voltage to less than a voltage step value in response to any of the obtained current readings that are higher than the maximum threshold current.

[0015] In one embodiment, the instruction, when executed by the processing circuitry, further causes the charging device to reduce the voltage step value in response to any of the obtained current readings that are higher than the maximum threshold current.

[0016] In one embodiment, obtaining a voltage reading from each of the multiple battery packs includes receiving the voltage reading from each of the multiple battery packs by the charger's processing circuitry, the voltage reading having been sent by the corresponding battery management system of each of the multiple battery packs.

[0017] In one embodiment, obtaining a current reading from each of the plurality of battery packs being charged includes receiving a current reading from each of the plurality of battery packs being charged by the processing circuitry of the charger, the obtained current reading having been sent by the corresponding battery management system of each of the plurality of battery packs being charged.

[0018] In some embodiments, the instruction, when executed by the processing circuitry, further causes the charging device to maintain the charging voltage until the charging protection switch of each of the multiple battery packs is closed in response to detecting that (A) the charging protection switch of at least one of the multiple battery packs is open and (B) the charging voltage exceeds the voltage of each of the multiple battery packs by at least a threshold amount. In one of these embodiments, the threshold amount is 1 volt.

[0019] In one embodiment, when the instruction is executed by the processing circuit, it also causes the charging device to maintain the charging voltage at the maximum charging voltage threshold in response to detecting that the charging voltage has reached the maximum charging voltage threshold. Attached Figure Description

[0020] As illustrated in the accompanying drawings, the foregoing and other objects, features, and advantages will become clear from the following description of specific embodiments of the invention, in which the same reference numerals refer to the same parts in different views. The drawings are not necessarily drawn to scale, but rather focus on illustrating the principles of various embodiments of the invention.

[0021] Figure 1 The illustrations depict example systems, devices, signals, and computer program products for use in conjunction with one or more embodiments.

[0022] Figure 2 Example methods according to one or more embodiments are shown.

[0023] Figure 3Example use cases according to one or more embodiments are shown. Detailed Implementation

[0024] As mentioned above, lithium-ion battery packs are typically equipped with a battery management system (BMS) to prevent overcharging, deep discharging, and charging with excessively high voltage differentials. In many systems, this protection may include a charge protection switch and / or a discharge protection switch, which are configured to prevent normal charging by switching to a trickle charging circuit.

[0025] Unfortunately, while trickle charging prevents charging at excessively high voltage differentials (i.e., "overcurrent" charging), its slow speed (e.g., potentially taking six times longer to charge) hinders timely charging of battery packs. Furthermore, when multiple battery packs are connected in parallel to the charger, the charging protection switch is particularly likely to activate trickle charging. For example, if the battery packs have uneven charge levels, the charger might start supplying charging current based on the voltage of the battery with more charge, potentially causing batteries with less charge to receive charging current with excessively high voltage differentials. This could trigger the BMS to activate the trickle charger to prevent damage to the lower-voltage batteries. Unfortunately, this can prevent the lower-voltage batteries from catching up with the higher-voltage batteries unless a very long period of time has passed. While this problem could be avoided by using a separate charger for each battery pack, doing so could be prohibitively expensive.

[0026] Therefore, it is desirable to implement a system for a single charger that utilizes parallel charging protection switches to charge multiple battery packs while minimizing the risk of trickle charging. This can be achieved by initially setting the charger to charge at the lowest voltage of any of the multiple battery packs attached in parallel with it, and then incrementally increasing the charging voltage in response to the current drawn by one or more of the battery packs falling outside a specified range.

[0027] Figure 1 An example system 30 is depicted for use in conjunction with the various embodiments described herein. System 30 includes a set of two or more batteries 32 (depicted as batteries 32(1), 32(2)...) connected to a charger device 40 via a charging cable 42.

[0028] Each battery pack 32 includes a battery 34 connected to ground 46 and a charging line 42 via two parallel paths. One path includes a discharge protection switch (DPS), such as a discharge field-effect transistor (DFET) 33, and a charge protection switch (CPS) 35, such as a charge field-effect transistor (CFET). The other path includes a trickle charge circuit (TCC) 36 configured to allow only trickle current to flow. As long as DPS 33 and CPS 35 remain closed, charging current from the charger 40 can flow through the first path, allowing standard charging of the battery pack 34. However, if CPS 35 is open, no current flows through the first path, and charging current from the charger 40 can only flow through the second path via TCC 36. In some embodiments, a BMS 38 operates to control DPS 33 and CPS 35. DPS 33 is configured to disconnect if the voltage of the battery pack 34 exceeds the charging voltage to prevent the battery 32 from discharging into the charger 40. CPS 35 is configured to disconnect under various conditions, such as when the charging voltage exceeds the battery voltage by a certain amount (e.g., 0.5 V, 1 V, etc.) or if BMS 38 determines that battery pack 34 is full.

[0029] Charger 40 includes control circuitry 50 and charging circuitry 58. The charging circuitry draws power from the mains grid 44 and ground 46 and uses this power to supply charging current to the battery pack 32 via charging line 42. Control circuitry 50 implements a voltage manager 56, which determines what voltage the charging circuitry 58 should supply to the charging line 42. In some embodiments, control circuitry 50 implements the logic of the voltage manager directly in dedicated circuitry. In other embodiments, control circuitry includes processing circuitry 52 coupled to memory 54, and the voltage manager 56 consists of computer code or instructions stored in memory 54 and executed on processing circuitry 52. ​​Processing circuitry 52 may include any type of processor or processor group configured to perform operations, such as, for example, a microprocessor, a multi-core microprocessor, a digital signal processor, a system-on-a-chip, an electronic circuitry set, a similar type of controller, or any combination thereof. Memory 54 may include any type of digital system memory, such as, for example, random access memory (RAM), read-only memory (ROM), one-time programmable (OTP) memory, and / or flash memory.

[0030] In operation, the communication circuit 39(X) of each battery pack 32(X) initially sends the voltage 60(X) of the battery 32(X) of that battery pack 32(X) to the voltage manager 56. In some embodiments, this communication can be sent using networking circuitry, while in other embodiments, it can be sent by modulating signals on the charging cable 42.

[0031] Then, voltage manager 56 determines the value of initial charging voltage 62 and instructs charging circuit 58 to supply initial charging voltage 62 to charging line 42. Initial charging voltage 62 is determined based on the lowest voltage 60 of all battery packs 32. For example, voltage manager 56 may set initial charging voltage 62 equal to the lowest voltage 60 of all battery packs 32. Alternatively, voltage manager 56 may set initial charging voltage 62 equal to the lowest voltage 60 of all battery packs 32 plus an offset (e.g., 0.5 V).

[0032] Once charging begins, the communication circuit 39(X) of each battery pack 32(X) being charged reports the current 64(X) that battery pack 32(X) is drawing to the voltage manager 56. In some embodiments, any battery pack 32(X) whose DPS 33 is disconnected does not report its current 64(X). In other embodiments, even if a battery pack 32(X) whose DPS 33 is disconnected reports its current 64(X), the voltage manager 56 ignores such readings.

[0033] If the current 64 of each reporting battery pack 32 (except for those whose DPS 33 is disconnected) is below the minimum threshold current value 66 (e.g., 1.0 A), the voltage manager 56 sets a new charging voltage 62' for the charging circuit 58 by increasing the initial voltage 62 by a voltage step value (VSV) 68 (e.g., 0.5 V). In some embodiments, the increase stops if the CPS 35 of any of the battery packs 32 is disconnected or if any of the battery packs 32 is in an error state.

[0034] In some embodiments, if the current 64 of any battery pack 32 is higher than the maximum threshold current value 70 (e.g., 2.5A), the voltage manager 56 sets a new charging voltage 62' by reducing a smaller version of the previous voltage 62 to VSV 68 (e.g., by splitting VSV 68 in half, such as from 0.5 V to 0.25 V). In some embodiments, once this occurs, VSV 68 itself is reduced forward (e.g., by cutting it in half, such as from 0.5 V to 0.25 V).

[0035] Figure 2An example method 100 for charging a parallel battery, executed by system 30, is illustrated. It should be understood that whenever a piece of software (e.g., voltage manager 56) is described as performing a method, process, step, or function, it means that a computing device (e.g., charger 40) running that piece of software executes that piece of software on its processing circuitry 52, performing that method, process, step, or function. It should be understood that in some embodiments, one or more steps or sub-steps of method 100 may be omitted. Similarly, in some embodiments, one or more steps or sub-steps may be combined or performed in different orders. Dashed lines indicate that steps or sub-steps are optional or represent alternative embodiments or use cases.

[0036] In step 110, the voltage manager 56 obtains a voltage reading 64 from each of the plurality of battery packs 32. For example, the voltage reading 64 may come from a corresponding communication circuit 39 for each battery pack 32.

[0037] In step 120, the voltage manager 56 initially sets the initial charging voltage 62 provided by the charging circuit 58 of the charger 40 to the lowest value among the received voltage readings 64 (or, in some embodiments, to the lowest value plus an offset, such as 0.5 V).

[0038] In step 130, when the charging circuit 58 applies a charging voltage (e.g., the initial charging voltage 62 when step 130 is performed for the first time or in the first few executions; or the updated charging voltage 62' when step 170 or 184 is performed once) to the plurality of battery packs 32 via the charging line 42, the voltage manager 56 obtains a corresponding current reading 64(X) from each battery pack 32(X) that is being charged (i.e., omitting any battery pack whose DPS 33 is disconnected). In some embodiments, step 130 includes a sub-step 135 in which a predetermined amount of time or delay 72 (e.g., 100 ms, 1 second, 1 minute, etc.) must elapse between subsequent current readings 64.

[0039] In some embodiments, in step 140, voltage manager 56 determines whether any of the battery packs 32 is in an error state, and if so, in step 145, voltage manager 56 maintains the current charging voltages 62, 62' until all errors are reset, after which the operation returns to step 120. Otherwise, the operation proceeds to step 150.

[0040] In step 150, voltage manager 56 determines whether the current reading 64 received from any of the battery packs 32 (excluding those whose DPS 33 is disconnected) is below a minimum current threshold (e.g., 1.0 A). If so, the operation proceeds directly to step 160, or in some embodiments, step 152 is performed first. Otherwise, the operation returns directly to step 130, or in some embodiments, step 180 is performed first.

[0041] In step 152, voltage manager 56 determines whether the CPS 35 of each battery pack 32 is closed. If yes, the operation proceeds to step 160. Otherwise, the operation proceeds to step 155. In step 155, voltage manager 56 determines whether the charging voltages 62, 62' exceed a voltage threshold (e.g., 1V) of the battery pack 32 with the highest voltage. If yes, in step 157, voltage manager 56 maintains the current charging voltages 62, 62' until the CPS 35 of each battery pack 32 is closed. Otherwise, the operation proceeds to step 160.

[0042] In step 160, voltage manager 56 determines whether the current charging voltages 62, 62' have reached the maximum voltage threshold 74 (e.g., 58V). If so, in step 165, voltage manager 56 maintains the current charging voltages 62, 62' until all battery packs 32 are fully charged. Otherwise, the operation proceeds to step 170.

[0043] In step 170, voltage manager 56 increases the charging voltage 62, 62' by VSV 68, and then the operation returns to step 130. VSV 68 has an initial value (e.g., 0.5 V), although it may decrease due to the operation in step 182.

[0044] In step 180, voltage manager 56 determines whether the current reading 64 received from any of the battery packs 32 is higher than the maximum current threshold 70 (e.g., 2.5 A). If so, the operation proceeds to step 182. Otherwise, the operation returns to step 130.

[0045] In step 182, voltage manager 56 reduces VSV 68. For example, VSV 68 can be halved. So if VSV 68 was initially 0.5 V, it will decrease to 0.25 V after one execution of step 182; after two executions of step 182, it will decrease to 0.125 V, and so on.

[0046] Then, in step 184, voltage manager 56 reduces the charging voltages 62, 62' to (the newly modified) VSV 68. The operation then returns to step 130.

[0047] Figure 3An example use case 200 is shown, including a voltage curve 202 and a current curve 204. In this use case 200, there are two battery packs 32(1) and 32(2), both connected to the same charger 40. The voltage curve 202 shows how the voltage 207(1) of battery pack 32(1) and the voltage 207(2) of battery pack 32(2) change over time. The charging voltages 62 and 62' are depicted as step functions 206, 206(i) with an initial value (representing the initial voltage 62) 206(a) and subsequent values ​​206(b), 206(c), ..., 206(a). The initial VSV 68 and 214(a) are shown as 0.5 V, and the voltage curve 202 also depicts how VSV 68 evolves to corrected values ​​214(b) and 214(c) of 0.25 V and 0.125 V, respectively. As depicted, the initial voltage 207(1) of battery pack 32(1) is 38.0 V, and the initial voltage 207(2) of battery pack 32(2) is 39.25 V.

[0048] Current curve 204 shows how the current 208(1) of battery pack 32(1) and the current 208(2) of battery pack 32(2) change over time. The minimum threshold current 66 is 1.0 A and the maximum threshold current 70 is 2.5 A. As depicted in use case 200, the delay 72 between current readings is 1 second.

[0049] At time = 1 second, voltage manager 56 receives initial voltage signals 60(1) = 38.0 V, 60(2) = 39.25 V (step 110) and sets the initial charging voltages 62, 206(a) to the lower voltage of 38.0 V (step 120). Since the voltage difference of battery pack 32(1) is zero, the charging current 208(1) of battery pack 32(1) is initially zero (or just above zero due to TCC 36(1)). Since the voltage difference of battery pack 32(2) is negative, DPS 33(2) is disconnected to prevent discharge, and the charging current 208(2) of battery pack 32(2) is initially zero (or just above zero due to TCC 36(2)).

[0050] At time = 2 seconds, voltage manager 56 receives (almost) zero charging current 208(1) (but not 208(2) because DPS 33(2) is off) (step 130). Since neither battery pack 32 is in an error state (step 140); the charging current 208(1) of battery 32(1) is (almost) zero, which is less than the minimum threshold current 66 of 1A (step 150); CPS 35 is fully closed (step 152); and the charging voltage of 38.0 V is less than the maximum charging voltage 74 of 58.0 V (step 160); voltage manager 56 increases the voltage step from the charging voltage 206(b) starting at 2 seconds until it reaches 38.5 V (step 170). Since the voltage difference of battery pack 32(1) is now positive, the charging current 208(1) of battery pack 32(1) immediately jumps and begins to decrease as battery pack 32(1) charges. Since the voltage difference of battery pack 32 (2) remains negative, DPS 33 (2) remains disconnected to prevent discharge, and the charging current 208 (2) of battery pack 32 (2) remains zero (or just above zero due to TCC 36 (2)).

[0051] At time = 3 seconds (and again at time = 4 seconds and 5 seconds), voltage manager 56 receives charging current 208(1) (but not 208(2) because DPS 33(2) is off) (step 130). Since neither battery pack 32 is in an error state (step 140); the charging current 208(1) of battery 32(1) is greater than the minimum threshold current 66 of 1.0 A (step 150); and the charging current 208(1) of battery 32(1) is less than the maximum threshold current 70 of 2.5 A (step 180); operation returns to step 130; and a delay of 72 (e.g., 1 second) is allowed (sub-step 135). Since the voltage difference of battery pack 32(2) remains negative, DPS 33(2) remains off to prevent discharge, and the charging current 208(2) of battery pack 32(2) remains zero (or just above zero due to TCC 36(2)).

[0052] At time = 6 seconds, voltage manager 56 receives charging current 208(1) (but not 208(2), because DPS 33(2) is off) (step 130). Since neither battery pack 32 is in an error state (step 140); the charging current 208(1) of battery 32(1) is now just below the minimum threshold current 66 of 1.0 A (step 150); CPS 35 is fully closed (step 152); and the charging voltage of 38.5 V is less than the maximum charging voltage 74 of 58.0 V (step 160); voltage manager 56 increases VSV 68, 214 (A) from the charging voltage 206(c) starting from 6 seconds until it reaches 39.0 V (step 170). Since the voltage difference of battery pack 32(1) is now higher, the charging current 208(1) of battery pack 32(1) immediately jumps and begins to decrease as battery pack 32(1) charges. Since the voltage difference of battery pack 32 (2) remains negative, DPS 33 (2) remains disconnected to prevent discharge, and the charging current 208 (2) of battery pack 32 (2) remains zero (or just above zero due to TCC 36 (2)).

[0053] At time = 7 seconds (and again at time = 8, 9 and 10 seconds), voltage manager 56 receives charging current 208(1) (but not 208(2) because DPS 33(2) is off) (step 130). Since neither battery pack 32 is in an error state (step 140); the charging current 208(1) of battery 32(1) is greater than the minimum threshold current 66 of 1.0 A (step 150); and the charging current 208(1) of battery 32(1) is less than the maximum threshold current 70 of 2.5 A (step 180); operation returns to step 130; and a delay of 72 (e.g., 1 second) is allowed (sub-step 135). Since the voltage difference of battery pack 32(2) remains negative, DPS 33(2) remains off to prevent discharge, and the charging current 208(2) of battery pack 32(2) remains zero (or just above zero due to TCC 36(2)).

[0054] At time = 11 seconds, voltage manager 56 receives charging current 208(1) (but not 208(2) because DPS33(2) is off) (step 130). Since neither battery pack 32 is in an error state (step 140); the charging current 208(1) of battery 32(1) is now just below the minimum threshold current 66 of 1.0 A (step 150); CPS 35 is fully closed (step 152); and the charging voltage of 39.0 V is less than the maximum charging voltage 74 of 58.0 V (step 160); voltage manager 56 increases VSV 68, 214 (A) from the charging voltage 206(d) starting at 11 seconds until it reaches 39.5 V (step 170). Since the voltage difference of battery pack 32(1) is now higher, the charging current 208(1) of battery pack 32(1) immediately jumps and begins to decrease as battery pack 32(1) charges. Since the voltage difference of battery pack 32 (2) is now positive, DPS 33 (2) is closed, and the charging current 208 (2) of battery pack 32 (2) immediately jumps and begins to decrease as battery pack 32 (2) charges.

[0055] At time = 12 seconds (and again at time = 13 seconds and 14 seconds), voltage manager 56 receives charging currents 208(1) and 208(2) (step 130). Since neither battery pack 32 is in an error state (step 140); charging currents 208(1) and 208(2) are both greater than the minimum threshold current 66 of 1.0 A (step 150); and charging currents 208(1) and 208(2) are both less than the maximum threshold current 70 of 2.5 A (step 180); operation returns to step 130; and a delay of 72 (e.g., 1 second) is allowed (sub-step 135).

[0056] At time = 15 seconds, voltage manager 56 receives charging currents 208(1) and 208(2) (step 130). Since neither battery pack 32 is in an error state (step 140); the charging current 208(2) of battery 32(2) is now just below the minimum threshold current 66 of 1.0 A (step 150) (even though the charging current 208(1) of battery 32(1) is still above the minimum threshold current 66 of 1.0 A); CPS 35 is fully closed (step 152); and the charging voltage of 39.5 V is less than the maximum charging voltage 74 of 58.0 V (step 160); voltage manager 56 increases VSV 68, 214 (A) from the charging voltage 206(e) starting at 11 seconds until it reaches 40.0 V (step 170). Since the voltage difference between the two battery packs 32(1) and 32(2) is now higher, the charging currents 208(1) and 208(2) immediately jump and begin to decrease as the battery packs 32(1) and 32(2) charge.

[0057] At time = 16 seconds, voltage manager 56 receives charging currents 208(1) and 208(2) (step 130). Since neither battery pack 32 is in an error state (step 140); charging currents 208(1) and 208(2) are both greater than the minimum threshold current 66 of 1.0 A (step 150); and the charging current 208(1) of battery 32(1) exceeds the maximum threshold current 70 of 2.5 A (step 180) (even though the charging current 208(2) of battery 32(2) is still lower than the maximum threshold current 70 of 2.5 A); operation proceeds to step 180. At this time, VSV 68 decreases from the initial value 214(a) of 0.5 V to a new value 214(B) of 0.25 V (step 182), and voltage manager 56 decreases the charging voltage 206(f) from 16 seconds to a new VSV 68, 214(B) to 39.75 V (step 184). Since the voltage difference between the two battery packs 32(1) and 32(2) is now low, the charging currents 208(1) and 208(2) immediately decrease and continue to decrease further as the battery packs 32(1) and 32(2) are charged.

[0058] At time = 17 seconds (and again at times = 18, 19, 20, 21, 22, and 23 seconds), voltage manager 56 receives charging currents 208(1) and 208(2) (step 130). Since neither battery pack 32 is in an error state (step 140); charging currents 208(1) and 208(2) are both greater than the minimum threshold current 66 of 1.0 A (step 150); and charging currents 208(1) and 208(2) are both less than the maximum threshold current 70 of 2.5 A (step 180); operation returns to step 130; and a delay of 72 (e.g., 1 second) is allowed (sub-step 135).

[0059] At time = 24 seconds, voltage manager 56 receives charging currents 208(1) and 208(2) (step 130). Since neither battery pack 32 is in an error state (step 140); the charging current 208(2) of battery 32(2) is now just below the minimum threshold current 66 of 1.0 A (step 150) (even though the charging current 208(1) of battery 32(1) is still above the minimum threshold current 66 of 1.0 A); CPS 35 is fully closed (step 152); and the charging voltage of 39.5 V is less than the maximum charging voltage 74 of 58.0 V (step 160); voltage manager 56 increases VSV 68 and 214(B) from the charging voltage 206(g) starting at 24 seconds until it reaches 40.0 V (step 170). Since the voltage difference between the two battery packs 32(1) and 32(2) is now higher, the charging currents 208(1) and 208(2) immediately jump and begin to decrease as the battery packs 32(1) and 32(2) charge.

[0060] At time = 25 seconds (and again at times = 26, 27, 28, 29, 30, 31, 32, and 33 seconds), voltage manager 56 receives charging currents 208(1) and 208(2) (step 130). Since neither battery pack 32 is in an error state (step 140); charging currents 208(1) and 208(2) are both greater than the minimum threshold current 66 of 1.0 A (step 150); and charging currents 208(1) and 208(2) are both less than the maximum threshold current 70 of 2.5 A (step 180); operation returns to step 130; and a delay of 72 (e.g., 1 second) is allowed (sub-step 135).

[0061] At time = 34 seconds, voltage manager 56 receives charging currents 208(1) and 208(2) (step 130). Since neither battery pack 32 is in an error state (step 140); the charging current 208(2) of battery 32(2) is now just below the minimum threshold current 66 of 1.0 A (step 150) (even though the charging current 208(1) of battery 32(1) is still above the minimum threshold current 66 of 1.0 A); CPS 35 is fully closed (step 152); and the charging voltage of 40.0 V is less than the maximum charging voltage 74 of 58.0 V (step 160); voltage manager 56 increases VSV 68 and 214(B) from the charging voltage 206(g) starting at 34 seconds until it reaches 40.25 V (step 170). Since the voltage difference between the two battery packs 32(1) and 32(2) is now higher, the charging currents 208(1) and 208(2) immediately jump and begin to decrease as the battery packs 32(1) and 32(2) charge.

[0062] At time = 35 seconds, voltage manager 56 receives charging currents 208(1) and 208(2) (step 130). Since neither battery pack 32 is in an error state (step 140); charging currents 208(1) and 208(2) are both greater than the minimum threshold current 66 of 1.0 A (step 150); and the charging current 208(1) of battery 32(1) exceeds the maximum threshold current 70 of 2.5 A (step 180) (even though the charging current 208(2) of battery 32(2) is still lower than the maximum threshold current 70 of 2.5 A); operation proceeds to step 180. At this time, VSV 68 decreases from the old value 214(B) of 0.25 V to a new value 214(C) of 0.125 V (step 182), and voltage manager 56 decreases the charging voltage 206(f) from 35 seconds to the new VSV 68, 214(C) to 40.125 V (step 184). Since the voltage difference between the two battery packs 32(1) and 32(2) is now low, the charging currents 208(1) and 208(2) immediately decrease and continue to decrease further as the battery packs 32(1) and 32(2) are charged.

[0063] At time = 36 seconds (and again at times = 37, 38, 39, 40, 41, 42, 43, and 44 seconds), voltage manager 56 receives charging currents 208(1) and 208(2) (step 130). Since neither battery pack 32 is in an error state (step 140); charging currents 208(1) and 208(2) are both greater than the minimum threshold current 66 of 1.0 A (step 150); and charging currents 208(1) and 208(2) are both less than the maximum threshold current 70 of 2.5 A (step 180); operation returns to step 130; and a delay of 72 (e.g., 1 second) is allowed (sub-step 135).

[0064] While various embodiments of the invention have been specifically shown and described, those skilled in the art will understand that various changes in form and detail may be made without departing from the spirit and scope of the invention as defined by the appended claims.

[0065] It should be understood that although various embodiments have been described as methods, software embodying these methods is also included. Thus, one embodiment includes a tangible computer-readable medium (such as, for example, a hard disk, floppy disk, optical disk, computer memory, flash memory, etc.) programmed with instructions that, when executed by a computer or a group of computers, cause one or more of the methods described in the various embodiments to be performed. Another embodiment includes a computer programmed to perform one or more of the methods described in the various embodiments.

[0066] Furthermore, it should be understood that all the implementation schemes described can be combined with each other in all possible combinations, unless such combinations are explicitly excluded.

[0067] Finally, nothing in this specification should be construed as an admission of any kind. Even if a technique, method, apparatus or other concept is specifically labeled as “background” or “conventional,” the applicant does not admit that such technique, method, apparatus or other concept is actually prior art under 35 USC §102 or 103, and such determination relies on a legitimate determination of many factors, not all of which are known to the applicant at this time.

Claims

1. A charging device, comprising: A charging circuit configured to be connected in parallel to multiple battery packs; and A processing circuit is configured to control the charging circuit by: Obtain voltage readings from each of the plurality of battery packs; The charger's charging voltage is initially set to the lowest voltage reading obtained from any of the plurality of battery packs; While the charging voltage is applied to the plurality of battery packs, a current reading is obtained from each of the plurality of battery packs that is being charged; and In response to the current reading obtained from the battery pack being lower than the minimum threshold current, the charging voltage is increased by a voltage step value.

2. The charging device according to claim 1, wherein, The processing circuit is further configured to control the charging circuit by reducing the charging voltage to less than the voltage step value in response to any of the obtained current readings that are higher than the maximum threshold current.

3. The charging device according to claim 1, wherein, The processing circuit is further configured to control the charging circuit by reducing the voltage step value in response to any of the obtained current readings that are higher than the maximum threshold current.

4. The charging device according to claim 1, wherein, Obtaining the voltage reading from each of the plurality of battery packs includes receiving the voltage reading from each of the plurality of battery packs, the voltage reading having been sent by the respective battery management system of each of the plurality of battery packs.

5. The charging device according to claim 1, wherein, Obtaining the current reading from each of the plurality of battery packs being charged includes receiving the current reading from each of the plurality of battery packs being charged, the obtained current reading having been sent by the corresponding battery management system of each of the plurality of battery packs being charged.

6. The charging device according to claim 1, wherein, The processing circuit is also configured to control the charging circuit in such a way that, in response to detecting (A) the charging protection switch of at least one of the plurality of battery packs is open and (B) the charging voltage exceeds the voltage of each of the plurality of battery packs by at least a threshold amount, the charging voltage is maintained until the charging protection switch of each of the plurality of battery packs is closed.

7. The charging device according to claim 6, wherein, The threshold value is 1 volt.

8. The charging device according to claim 1, wherein, The processing circuit is further configured to control the charging circuit by maintaining the charging voltage at the maximum charging voltage threshold in response to detecting that the charging voltage has reached the maximum charging voltage threshold.

9. A method for charging multiple battery packs in parallel, the method comprising: Obtain voltage readings from each of the plurality of battery packs; The charging voltage is initially set to the lowest voltage reading obtained from any of the plurality of battery packs; While the charging voltage is applied to the plurality of battery packs, a current reading is obtained from each of the plurality of battery packs that is being charged; and In response to the current reading obtained from the battery pack being lower than the minimum threshold current, the charging voltage is increased by a voltage step value.

10. The method according to claim 9, wherein, The method further includes: in response to any of the obtained current readings being higher than the maximum threshold current, reducing the charging voltage to less than the voltage step value.

11. The method according to claim 9, wherein, The method further includes: in response to any of the obtained current readings being higher than the maximum threshold current, decreasing the voltage step value.

12. The method of claim 9, wherein the method further comprises: In response to detecting that (A) the charging protection switch of at least one of the plurality of battery packs is open and (B) the charging voltage exceeds the voltage of each of the plurality of battery packs by at least a threshold amount, the charging voltage is maintained until the charging protection switch of each of the plurality of battery packs is closed.

13. A computer program product comprising a non-transitory computer-readable storage medium storing instructions, said instructions, when executed by processing circuitry of a charging device, causing the charging device to charge a plurality of battery packs in parallel in such a manner as: Obtain voltage readings from each of the plurality of battery packs; The charging voltage of the charging device is initially set to the lowest voltage reading obtained from any of the plurality of battery packs; While the charging voltage is applied to the plurality of battery packs, a current reading is obtained from each of the plurality of battery packs that is being charged; and In response to the current reading obtained from the battery pack being lower than the minimum threshold current, the charging voltage is increased by a voltage step value.

14. The computer program product according to claim 13, wherein, When executed by the processing circuit, the instruction further causes the charging device to reduce the charging voltage to less than the voltage step value in response to any of the obtained current readings that are higher than the maximum threshold current.

15. The computer program product according to claim 13, wherein, When executed by the processing circuit, the instruction further causes the charging device to reduce the voltage step value in response to any of the obtained current readings that are higher than the maximum threshold current.

16. The computer program product according to claim 13, wherein, Obtaining the voltage reading from each of the plurality of battery packs includes receiving the voltage reading from each of the plurality of battery packs by the processing circuitry of the charger, the voltage reading having been sent by the corresponding battery management system of each of the plurality of battery packs.

17. The computer program product according to claim 13, wherein, Obtaining the current reading from each of the plurality of battery packs being charged includes: receiving the current reading from each of the plurality of battery packs being charged by the processing circuitry of the charger, the obtained current reading having been sent by the corresponding battery management system of each of the plurality of battery packs being charged.

18. The computer program product according to claim 13, wherein, When the instruction is executed by the processing circuit, the charging device also causes the charging device to maintain the charging voltage until the charging protection switch of each of the plurality of battery packs is closed in response to detecting (A) the charging protection switch of at least one of the plurality of battery packs is open and (B) the charging voltage exceeds the voltage of each of the plurality of battery packs by at least a threshold amount.

19. The computer program product according to claim 18, wherein, The threshold value is 1 volt.

20. The computer program product according to claim 13, wherein, When the instruction is executed by the processing circuit, the charging device also causes the charging voltage to maintain at the maximum charging voltage threshold in response to detecting that the charging voltage has reached the maximum charging voltage threshold.

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