Work vehicle with multi-mode power distribution unit for swappable batteries

Abstract

A work vehicle (100) includes an electric work motor (103) and a main battery (104) operable to drive the electric work motor (103). The work vehicle (100) includes a power distribution unit (109) coupled to the main battery (104) and a swappable accessory interface (110) operable to electrically and mechanically couple an accessory battery (106) to the work vehicle (100). The power distribution unit (109) includes circuitry operable in one or both of a first mode and a second mode. The main battery (104) provides charging energy to the accessory battery (106) in the first mode, and the accessory battery (106) provides work energy that augments driving of the electric work motor (103) in the second mode.

Description

PATENT Docket No. 0206.000354W001 WORK VEHICLE WITH MULTI-MODE POWER DISTRIBUTION UNIT FOR SWAPPABLE BATTERIES

[0001] This application claims the benefit of U.S. Provisional Pat. App. No.63 / 760,778, filed on 20 February 2025. Each of the documents identified in this paragraph is incorporated herein by reference in its entirety.

[0002] Embodiments described herein are directed generally to a work vehicle (e.g., mower) having a multi-mode power distribution unit for swappable batteries.SUMMARY

[0003] The present disclosure is directed to a work vehicle with a multiple mode power distribution unit for swappable batteries. In one embodiment, a work vehicle includes an electric work motor and a main battery operable to drive the electric work motor. The work vehicle includes a power distribution unit that is coupled to the main battery and a swappable accessory interface operable to electrically and mechanically couple an accessory battery to the work vehicle. The power distribution unit includes circuitry operable to change between a first mode and a second mode. The main battery provides charging energy to the accessory battery in the first mode, and the accessory battery provides work energy that augments driving of the electric work motor in the second mode.

[0004] In another embodiment, a circuit-implemented method involves detecting an accessory battery installed in a swappable accessory interface that electrically and mechanically couples the accessory battery to a work vehicle. The work vehicle incudes an electric work motor and a main battery operable to drive the electric work motor. A user selection between a first mode and a second mode is detected. In response to detecting selection of the first mode, charging energy is provided from the main battery to the accessory battery. In response to detecting selection of the second mode, work energy is provided from the accessory battery to augment driving of the electric work motor.

[0005] In another embodiment, a system includes a portable ground maintenance tool or machine powered by a swappable accessory battery. The system also includes a work vehicle with an electric work motor and a main battery operable to drive the electric work motor. A power distribution unit is coupled to the main battery. A swappable accessory interface is operable to electrically and mechanically couple the accessory battery to the work vehicle. The power distribution unit includes circuitry operable to provide charging energy to the accessory battery in a first mode. These and other features and aspects of various embodiments may be understood in view of the following detailed discussion and accompanying drawings.BRIEF DESCRIPTION OF THE DRAWINGS

[0006] The discussion below makes reference to the following figures, wherein the same reference number may be used to identify the similar / same component in multiple figures. The drawings are not necessarily to scale.

[0007] FIG. 1 is a perspective view of a battery powered vehicle and charging system according to an example embodiment;

[0008] FIG. 2 is a block diagram of a battery powered vehicle and charging system according to an example embodiment;

[0009] FIGS. 3-5 are diagrams illustrating a user interface in various modes according to an example embodiment, wherein: FIG. 3 illustrates a main battery icon charging an accessory battery icon (“accessory charge”) while also powering a work motor icon; FIG. 4 illustrates another mode wherein the accessory battery icon is now providing assistance (“motor assist”) to the work motor icon; and FIG. 5 illustrates a DC charge icon charging the main battery icon;

[0010] FIG. 6 is a schematic diagram of a power distribution system according to an example embodiment; and

[0011] FIG. 7 is a flowchart of a method according to an example embodiment.DETAILED DESCRIPTION

[0012] In the following detailed description of illustrative embodiments, reference is made to the accompanying figures of the drawing which form a part hereof. It is to be understood that other equivalent embodiments, which may not be described and / or illustrated herein, are also contemplated.

[0013] This disclosure relates to battery-powered machines such as work vehicles and stationary work machines. Work vehicles such as ground care machines, construction machines, and utility machines are used in various consumer and commercial applications. Such vehicles generally include a traction unit (e.g., wheels, treads) and a work unit for performing ground care tasks, construction tasks, and miscellaneous utility tasks. Ground care tasks include mowing, material collection, spraying, dethatching, edging, rolling, snow / ice treatment and removal, etc. Construction tasks include digging, trenching, lifting, scraping, demolition, grappling, etc. Utility tasks include towing, passenger carrying, hauling, recharging, surveillance, etc. This categorization is meant for illustration and not limitation. For example, a ground care vehicle such as a tractor lawn mower can often be adapted for towing and material hauling. Similarly, some stationary machines such as cement mixers, chippers, log splitters, boring machines, etc., may require similar amounts of power as a work vehicle even though they do not include a powered traction system.

[0014] Traditionally, work vehicles and large stationary machines have been powered by internal combustion engines (ICE). Increasingly, work vehicles have employed batteries and electric motors in place of ICE engines. Some of the reasons this has become popular is that, compared to ICE power, battery powered machines have reduced emissions, are quieter, and require less regular maintenance. Thus, it is expected that electrically powered work vehicles / machines will gain increasingly larger market share compared to ICE powered work vehicles / machines.

[0015] In FIG. 1, a perspective view shows details of an electrically powered work vehicle 100 according to an example embodiment. This vehicle is a utility carrier, although in other embodiments may be any combination of a mower, tractor, front-end loader, fork lift, greens roller, material handler, compact utility loader, etc. (e.g., as indicated by diagrammatic implement 201 in FIG. 2). The vehicle 100 includes a traction unit that drives front and / or back wheels 102 via one or more electric motors 103. Afixed / main battery 104 provides electrical energy to drive the traction unit (electric motors 103) and accessories, such as a work implement, instruments, headlights, etc. For purposes of this disclosure, a “fixed” or “fixable” battery is one that is not intended or designed to be removed and / or replaced on a regular (e.g., daily) basis, in other words is fixably mounted. While a fixed battery can typically be removed and replaced, this generally involves removing surrounding structures, use of hand or power tools (e.g., sockets, wrenches), and is relatively time consuming. In contrast, a swappable battery (also referred to herein as an accessory battery) includes a physical attachment mechanism with an optional locking interface (e.g., clips, button) that can be manually actuated without tools to quickly attach and detach a battery. The swappable physical battery interface also typically includes a connector interface that is connected and disconnected at the same time the battery is respectively attached and detached.

[0016] Swappable batteries (e.g., accessory battery 106) are commonly used in electrically-powered handheld tools such as drills, saws, leaf blowers, string trimmers, and the like. A leaf blower 108 is illustrated in FIG. 1 as an example of a handheld tool and is intended to exemplify a portable ground care or maintenance tool or machine powered by such batteries that can be used in ground care tasks as enumerated above. It will be understood that the concepts described relating to handheld tool batteries may also be applicable to small, electrically-powered, rolling tools or machines such as walk-behind mowers, turf rollers, and the like and / or fixed machines such as leaf shredders. These devices will be described herein as “accessory tools” in that they use swappable batteries having a storage capacity that is significantly less (e.g., <20%) than that of the main battery 104. Typically, the accessory tools can be carried in or by the vehicle during work, e.g., forming a mobile ground maintenance system for work on a job site.

[0017] While swappable batteries have proved a popular and effective choice for smaller machines, swappable batteries or not as prevalent in work vehicles and large stationary machines. For example, the large energy storage capacity needed for larger vehicles / machines can result in heavy batteries, which can be difficult to manually swap out. Even though there may be wide differences in form factor and capacity of swappable accessory batteries and main / fixed vehicle batteries (or main batteries in larger, fixed operation, machines), there may be advantages in coupling both types of batteries to a common power distribution unit (PDU) of the vehicle or fixed machine. For example,many tasks involve a vehicle transporting workers to a job site where they may do work with the vehicle and / or with accessory power tools. Since battery power is becoming increasingly desirable for both larger and smaller machines, there are advantages in having a PDU couple to and manage both the larger fixed battery and smaller, swappable accessory batteries.

[0018] The work vehicle 100 in FIG. 1 includes a power distribution unit (PDU) 109 coupled to the main battery 104 that in some configurations drives the electric work motor 103. The vehicle 100 includes a swappable accessory interface 110 operable to electrically and mechanically couple the accessory battery 106 to the work vehicle 100. The power distribution unit 109 can be coupled to the accessory battery 106 via the accessory interface 110 and is also coupled to the main battery 104 (which may be fixably mounted to the work vehicle) via internal wiring of the vehicle. The power distribution unit 109 includes circuitry operable to change between a first mode (e.g., accessory charge mode) and a second mode (e.g., motor assist mode), both modes affecting the accessory battery 106 and main battery 104. In some embodiments, the power distribution unit 109 may be operable in just one of the first and second modes.

[0019] In the first mode, the power distribution unit 109 causes the main battery 104 to provide charging energy to the accessory battery 106. The first mode assists in cases where the accessory battery 106 might be depleted during a work session. By charging the accessory battery 106 from the main battery 104, the former can take advantage of the relatively large capacity of the latter, thus freeing the operator from having to carry a spare battery, for example, or reduce the number of spare batteries needed. If the accessory tool can remain idle for sufficient time to allow recharging (e.g., while transiting between different work sites) then no spare battery may be needed. If the working schedule does not provide enough time to charge the accessory battery, a spare accessory battery could be provided such that one is charging while the other is in use. This can reduce the number of spare batteries that might be needed to perform the same amount of work.

[0020] Note that the operator may want to prioritize usability of the main battery 104 over the accessory batteries 106. Therefore, while operating in the first mode, the power distribution unit 109 may detect that a state of charge of the main battery 104 falls below a first threshold. In response thereto, the power distribution unit 109 stopsproviding charging energy to the accessory battery 106. The first threshold can be set via a user input, although there may be hard-coded lower threshold limits based on other factors, e.g., a restricted (e.g., “limp”) mode once a low state of charge is reached. The power distribution unit is also operable to detect, while operating in the first mode, that a state of charge of the main battery falls below a second threshold, and in response thereto, switch to the second mode.

[0021] In the second mode, the accessory battery 106 provides additional (“work”) energy usable to augment driving of the electric work motor and other accessories of the vehicles (e.g., lights, power take off). The power provided to the electric work motor may be unchanged whether the accessory battery 106 is used or not, such that the accessory battery 106 represents extra “fuel” to extend operating time but not does not increase motor current or the like. In other embodiments, the power distribution unit may be configured to cause the accessory battery 106 to augment or boost the electric work motor, e.g., allows for higher motor current if the accessory battery 106 is in use in the second mode.

[0022] An operator may use a set of accessory batteries 106 dedicated for use in the second mode. This may provide a more cost-effective means of increasing the amount of work done with the vehicle compared to, for example, purchasing a machine with a larger fixed battery. The operator may also use the accessory batteries 106 for powering tools or machines separate from the work vehicle during work sessions, with the understanding that the accessory batteries 106 may be somewhat depleted due to some of the energy being used by the vehicle. This may be acceptable in situations where the tool or machine does not consume a large percentage of battery energy during use or is infrequently used, e.g., is brought along for contingency reasons, such as a chain saw used to occasionally clear brush. The operator can set the second mode to increase the range of the work vehicle. In the second mode, the accessory battery will slowly discharge together with the main battery 104 in driving motors and other devices to extend the usability of the main battery 104. The second mode can be configured to minimize or limit fast discharge (e.g., limit maximum discharge current) and / or to minimize or limit deep discharge of the accessory battery 106. The limiting of discharge rate and / or depth can be set to extend life of the accessory battery if desired. This is opposed to modes where the full capacity and / or current of the accessory battery is used,e.g., in a backup capacity that allows a limited mode of operation when the main battery has little or no energy left. The discharge of the accessory battery 106 in the second mode can also be limited based on the state of charge of the accessory battery 106, e.g., current flow limited or stopped from the accessory battery once its state of charge is below X%.

[0023] In some cases, gradual discharge of the accessory battery 106 may be enforced by limiting a discharge rate of the accessory battery 106 to some fraction of its maximum discharge rate, e.g., less than half of its maximum discharge rate. In other cases, the output current of the accessory battery 106 may be scaled in proportion to the energy capacity and / or maximum discharge currents of the respective main and accessory batteries. For example, if the main battery has X kWh energy storage capacity and the accessory battery has 0.05 *X kWh storage capacity, then the current draw of the accessory battery 106 could be kept to 5% that of the main battery 104 during use in the second mode. A similar scheme could be devised based on maximum discharge currents of the batteries, e.g., if the main battery’s maximum discharge current is Y amps and the and the accessory battery has 0.1 *Y amps maximum discharge current, then the current draw of the accessory battery could be kept to 10% that of the main battery during use in the second mode.

[0024] In many configurations, the main battery has a higher nominal voltage than a corresponding nominal voltage of the accessory battery. A non-limiting example of main battery voltage is 60VDC and 120VDC. There are a wide range of accessory battery voltages, e.g., 12V, 18V, 20V, 24V, 36V, 40V and 60V. The modes described above will generally involve a DC-DC conversion, e.g., at the PDU 109, where the main and accessory bus voltages differ.

[0025] The work vehicle 100 may typically rely on an alternating current (AC) electrical source for charging the main battery 104, such as from a 110V or 220V mains power outlet. This involves rectifying the AC source current to provide a direct current (DC) charge current, which is a well-known and effective means of recharging a smaller work vehicle. Note that in an AC charging mode, the AC charger and / or main battery 104 can also charge the accessory battery 106 should it be installed in the accessory interface 110 during AC charging.

[0026] There are also DC chargers on the market that directly provide a DC current without requiring rectification within an external charging adapter. Local sourcesof DC power may be available for use as a DC charger for a work vehicle fleet, such as solar panels and / or backup batteries attached to or within a storage building. In such a case where a local DC source is available, the vehicle’s power distribution unit 109 could operate in a third mode in which a DC connector (charging connector) 112 is electrically and mechanically coupled to power distribution unit 109, e.g., via the swappable accessory interface 110 and / or via a dedicated connector. In some embodiments, the power distribution unit 109 may be operable in the first, second and third modes, or any two selected from the three modes, e.g., the first and third mode or the second and third mode.

[0027] In the third mode, a DC charger (not shown) charges the main battery 104 via the DC connector 112 coupled the work vehicle. The third mode may operate similarly to the second mode except that any limiting of the current from the DC charger would be for purposes of maximum charge current of the main battery 104 or for other current / power limitations in the electrical system. Another difference between the second and third modes is that the work vehicle 100 (e.g., PDU) may include lockouts in the third mode to prevent actuation / operation of the electric work motor 103 or any other motor that could cause movement that would be problematic with an attached cable. The work vehicle 100 may already include similar motor lockouts when operating in an AC charging mode. Such lockouts would not be needed if the accessory battery 106 was connected in the second mode to the accessory interface 110.

[0028] In FIG. 2, a block diagram illustrates an electric machine 200 according to an example embodiment. While this disclosure may describe the machine 200 as a battery powered work vehicle, the concepts may apply to any battery powered machine that has high power requirements, such as cement mixers, wood chippers, portable saw mills, etc. The machine 200 includes a main battery 202, an electric work motor 204, and a PDU 206 similar to those described in relation to FIG. 1. The PDU 206 is operable in different accessory operating modes 207a-207n as described herein, including first through third modes described above. At least some of the modes 207a-207n are selected by a user interface 209, although some modes (e.g., third DC charging mode) may be automatically selected.

[0029] The machine 200 has one or more charging bays 208 configured for receiving swappable accessory battery packs or accessory batteries 210. The chargingbays 208 include connectors and other features in the previously-described swappable accessory interface. This example shows two charging bays 208 that can be used to simultaneously charge the two battery packs 210 from the main battery 202 in the first mode. The two battery packs 210 can augment the main battery 202 in the second mode.

[0030] The existence of two accessory interfaces allows for an adaptation in the third DC charging mode, should it be implemented. In the third mode, a DC charger 212 (e.g., could include one or both of a solar panel(s) or cell(s) 213 or external battery 215) charges the main battery 202 via a DC charging connector 214 coupled to one of the bays 208 in place of one of the accessory battery packs 210. At least one of the charging bays 208 could accept DC current from the DC charger 212 to charge the main battery 202. The other charging bay could hold an accessory battery pack 210, which could be charged together with the main battery 202 via the DC charger 212.

[0031] In one embodiment, the external battery 215 includes an array of batteries 216 similar to the accessory battery packs 210. This could be used as a fixed battery charging station (e.g., in the operator’s garage). In some embodiments, additional or “old” batteries 216 could be utilized as an energy storage bank that could be charged during off-peak hours or through other sustainable methods (e.g., solar, wind, etc.), and then charge the main battery 202 of the machine 200 via the DC charger 212 and PDU 206. In another embodiment, an external battery could include a battery system fixably mounted to a trailer (not shown) that is stored together with the machine 200.

[0032] In order to have an operator effectively utilize the different modes, a user interface or control may be provided that illustrates the general operation of the PDU in the various modes while also facilitating switching between the different modes. In FIGS.3-5, diagrams illustrate a user interface or control 300 that can be implemented via a user interface attached to the vehicle or accessible via a mobile device. In FIG. 3, the example of the first mode is shown, in which a main battery icon 301 is shown charging an accessory battery icon 302 as well as powering a work motor icon 303. The direction of arrows 310, 312 indicate a direction of current flow between the various icons, and the arrows could be animated to indicate current presently flowing. Further the battery icons 301, 302 could indicate respective states of charge, temperature, etc., by using bar graphs, colors, etc. A first (pushbutton) control 304 is shown with bold outline, indicating that it is currently selected. A second (pushbutton) control 306 is shown in dotted outline,indicating it is not currently selected, but is selectable. Both controls 304, 306 include descriptive text indicating their function, and may be implemented using other user interface controls besides touchscreen buttons.

[0033] In FIG. 4, the second control 306 has been selected, causing a change of direction of arrow 312. The direction of arrow 312 indicates the accessory battery icon 302 is assisting the main battery icon 301 as in the second mode described above. Note that these arrows need not be literally how the second mode is implemented (e.g., current may be sent directly in parallel from both batteries to the motor) but may help communicate that the accessory battery is operating in an augmentation mode and not replacing the main battery as an energy source. Alternatively, arrow 312 could instead be directed to a middle part of arrow 310 to indicate parallel discharge of both batteries into the motor in alternate configurations described above.

[0034] As noted above, the third mode, if implemented, could be automatically triggered by detecting a DC charger connector being coupled to the accessory battery interface or by a user selection. This is indicated in FIG. 5, in which a new DC charge icon 500 appears, with arrow 502 indicating charge of the main battery icon 301. The arrows 310, 312 from FIGS. 3 and 4 have disappeared, and the work motor icon 303 is shown in dotted line, indicating it is disabled in this mode. The first and second controls 304, 306 are shown in dotted lines indicating the respective first and second modes are not in operation. In FIG. 5, the first and second controls 304, 306 are also shown with diagonal lines indicating they are not selectable in this mode. There may be many variations on these figures, including cases where more than one accessory battery can be coupled to the work vehicle.

[0035] While the user interface illustrated in FIGS. 3-5 is one example of how to communicate selection of the various modes, other implementations are possible. For example, the accessory interface (charging bays) may have a toggle switch near the receiving port that allows selecting between the different modes. The toggle switch in such an embodiment is electrically coupled to provide an input to the PDU. For embodiments with more than one accessory battery interface (bay) where each bay has a dedicated toggle switch, this could allow a first accessory battery to be in the first mode while a second accessory battery is in the second mode. In other embodiments, a single switch could control the mode of both bays, e.g., both bays may be tied to a same mode.If a DC charger is detected in these embodiments, the toggle switch function could be ignored at the PDU, such that DC charging will occur regardless of the position of the toggle.

[0036] In FIG. 6, a schematic diagram shows electrical details of a work vehicle electrical system according to an example embodiment. The diagram shows interconnections between a PDU 600, an accessory battery system 601, a main battery system 602, a battery charging system 603, and a mode selector 604. Note that in addition to energy storage cells, the accessory battery system 601 and main battery system 602 will include other control electronics, such as a battery management unit that manages individual storage cells as well as communications with external devices such as the PDU 600. The charging system 603 will also include a compatible communication interface for communicating using main data bus lines 610, 611. The accessory battery system 601 will be at least in part swappable and / or removable and installable without tools.

[0037] Main power bus lines 606 and 607 represent a DC power bus for the main battery system 602 and charging system 603. Accessory power bus lines 608 and 609 represent a DC power bus for the accessory battery system 601. The main power bus lines 606, 607 and accessory power bus lines 608, 609 will often operate at different voltages. Further, the accessory bus voltage is lower than the main bus voltage in many cases, although the accessory bus may be able to accommodate more than one nominal voltage, e.g., between 24V and 48V.

[0038] Controller area network (CAN) data bus lines 610, 611 manage communications between the PDU 600, the main battery system 602 and the charging system 603. The two CAN data lines 612, 613 manage communications between the PDU 600 and the accessory battery system 601. Other protocols and communications media besides CAN over wire may be used. A proprietary control line (pin) 614 is also shown between the PDU 600 and the accessory battery system 601. The PDU 600 may contain multiple such control lines to handle different connection scenarios and different communication buses (e.g., I2C, RS-232, Ethernet). Generally, the CAN data lines and / or other data lines can provide such information as detecting whether an accessory battery or DC connector cable is coupled to the interface, the type of device, device identifiers (e.g., model / version number), maximum current, temperature sensor data, fault codes, etc.

[0039] The mode selector 604 is tied to a user interface device, such as a switch, controller, or the like. It selects modes that control, among other things, the direction of current between the PDU 600, the accessory battery system 601, and the main battery system 602. This may affect the battery charging system 603 in a third mode, assuming a DC charging capability is added to the electrical system. For example, in an AC charging mode, the battery charging system 603 will receive power from the AC grid / mains (not shown) and directly regulate charging power supplied to the main power bus lines 606, 607. In a DC charging mode where a charger is coupled via or configured as the accessory battery system 601, the battery charging system 603 may indirectly regulate charging power supplied to the main power bus lines 606, 607 via the PDU 600. This may be coordinated via the data communications main data bus lines 610-613.

[0040] In FIG. 7, a flowchart shows a circuit-implemented method according to an example embodiment. The method is operated in a circuit of an electrically-driven work vehicle, e.g., operated via a PDU that includes any combination of power control circuits and logic circuits. The logic circuits include a discrete logic state machine, EEPROM, microprocessors, system on a chip, etc. The method involves detecting 700 an accessory battery installed in a swappable accessory interface of the electrically-driven work vehicle. As stated elsewhere herein, the accessory interface electrically and mechanically couples the accessory battery to the work vehicle. An accessory operating mode is detected or determined 701, e.g., via user selection input, preference, default, etc. In response the accessory operating mode is set to an accessory charge mode 702 (first mode), during which the main battery provides 704 charging energy to the accessory battery, e.g., via circuitry in a PDU or other controller. In response to detecting motor assist mode 703 at block 701 (second mode), the accessory battery provides 705 work energy via the circuitry that augments the driving of the electric work motor driven by the main battery. The electric work motor may include one or more traction (drive) motors, work implement motors, etc.

[0041] The method may optionally involve a DC charge mode (third mode) that may be determined, for example, by block 701 detecting a DC charger being electrically and mechanically coupled to the work vehicle. In response thereto, the work vehicle (e.g., via a PDU or the like) enters a DC charge mode 706 wherein the DC charger charges 707 the main battery via a DC connector of the DC charger coupled to the swappableaccessory interface. While not illustrated in FIG. 7, the method may also include detecting, while operating in the first mode, that a state of charge of the main battery falls below a first threshold and, in response thereto, stopping provision of the charging energy to the accessory battery.

[0042] While the present disclosure is not so limited, an appreciation of various aspects of the disclosure will be gained through a discussion of the specific illustrative aspects provided below. Various modifications of the illustrative aspects, as well as additional aspects of the disclosure, will become apparent herein.

[0043] Example 1 is a work vehicle comprising: an electric work motor; a main battery operable to drive the electric work motor; a power distribution unit coupled to the main battery; a swappable accessory interface operable to electrically and mechanically couple an accessory battery to the work vehicle, wherein the power distribution unit comprises circuitry operable to change between a first mode and a second mode. The main battery provides charging energy to the accessory battery in the first mode, and the accessory battery provides work energy that augments driving of the electric work motor in the second mode.

[0044] Example 2 includes the work vehicle of example 1, wherein the main battery is fixably mounted to the work vehicle. Example 3 includes the work vehicle of example 1 or 2, wherein the main battery has a higher nominal voltage than a corresponding nominal voltage of the accessory battery.

[0045] Example 4 includes the work vehicle of any one of examples 1-3, wherein the swappable accessory interface is configured to electrically and mechanically couple a direct current (DC) connector to the work vehicle, the circuitry of the power distribution unit operable in a third mode wherein a DC charger charges the main battery via the DC connector coupled to the work vehicle. Example 5 includes the work vehicle of example 4, wherein the DC charger comprises one of both of a solar cell and a battery array. Example 6 includes the work vehicle of example 4 or 5, wherein the power distribution unit is operable in the third mode to prevent actuation of the electric work motor.

[0046] Example 7 includes the work vehicle of any one of examples 1-6, wherein in the second mode, a discharge rate of the accessory battery is limited to less than half of a maximum discharge rate of the accessory battery. Example 8 includes the work vehicle of any one of examples 1-6, wherein in the second mode, a discharge rate or dischargecurrent of the accessory battery is tied to a corresponding discharge rate or corresponding discharge current of the main battery.

[0047] Example 9 includes the work vehicle of any one of examples 1-8, wherein the electric work motor is a traction motor. Example 10 includes the work vehicle of examples 1-8, wherein the electric work motor is a work implement motor. Example 11 includes the work vehicle of any one of examples 1-10, wherein the work vehicle comprises any combination of a tractor, a mower, a front-end loader, a fork lift, a greens roller, a material handier, and a compact utility loader. Example 12 includes the work vehicle of any one of examples 1-11, further comprising a user control that facilitates switching between the first mode and the second mode. Example 13 includes the work vehicle of any previous example, wherein the power distribution unit is operable to detect, while operating in the first mode, that a state of charge of the main battery falls below a first threshold, and in response thereto, stop providing the charging energy to the accessory battery. Example 14 includes the work vehicle of any previous example, wherein the power distribution unit is operable to detect, while operating in the first mode, that a state of charge of the main battery falls below a second threshold, and in response thereto, switch to the second mode. Example 15 includes the work vehicle of any previous example, wherein the accessory battery is operable to power a tool or machine separate from the work vehicle.

[0048] Example 16 is a circuit-implemented method comprising: detecting an accessory battery installed in a swappable accessory interface that electrically and mechanically couples the accessory battery to a work vehicle, the work vehicle comprising an electric work motor and a main battery operable to drive the electric work motor; detecting a user selection between a first mode and a second mode; in response to detecting selection of the first mode, providing charging energy from the main battery to the accessory battery; and in response to detecting selection of the second mode, providing work energy from the accessory battery to augment driving of the electric work motor.

[0049] Example 17 includes the method of example 16, further comprising detecting a direct current (DC) charger electrically and mechanically coupled to the work vehicle, and in response thereto entering a third mode wherein the DC charger charges the main battery via a DC connector of the DC charger coupled to the swappable accessoryinterface. Example 18 includes the method of example 16 or 17, further comprising: detecting, while operating in the first mode, that a state of charge of the main battery falls below a first threshold; and in response thereto, stopping provision of the charging energy to the accessory battery.

[0050] Example 19 is a system comprising: a portable ground maintenance tool or machine powered by a swappable accessory battery; and a work vehicle comprising: an electric work motor; a main battery operable to drive the electric work motor; a power distribution unit coupled to the main battery; and a swappable accessory interface operable to electrically and mechanically couple the accessory battery to the work vehicle, wherein the power distribution unit comprises circuitry operable to provide charging power to the accessory battery in a first mode.

[0051] Example 20 includes the system of example 19, wherein the circuitry of the power distribution unit is further operable to switch between the first mode and a second mode, the power distribution unit providing work energy from the accessory battery to augment driving of the electric work motor in the second mode. Example 21 includes the system of example 19 or 20, wherein the ground maintenance tool or machine is carried in or by the work vehicle during work.

[0052] It is noted that the terms “have,” “include,” “comprises,” and variations thereof, do not have a limiting meaning, and are used in their open-ended sense to generally mean “including, but not limited to,” where the terms appear in the accompanying description and claims. Further, “a,” “an,” “the,” “at least one,” and “one or more” are used interchangeably herein. Moreover, relative terms such as ’’left,” “right,” “front,” “fore,” “forward,” “rear,” “aft,” “rearward,” “top,” “bottom,” “side,” “upper,” “lower,” “above,” “below,” “horizontal,” “vertical,” and the like may be used herein and, if so, are from the perspective shown in the particular figure, or while the machine or vehicle is in an operating configuration. These terms are used only to simplify the description, however, and not to limit the interpretation of any embodiment described. As used herein, the terms “determine” and “estimate" may be used interchangeably depending on the particular context of their use, for example, to determine or estimate a position or pose of a vehicle, boundary, obstacle, etc.

[0053] Further, it is understood that the description of any particular element as being connected to or coupled to another element can be directly connected or coupled, or indirectly coupled / connected via intervening elements.

[0054] Unless otherwise indicated, all numbers expressing feature sizes, amounts, and physical properties used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the foregoing specification and attached claims are approximations that can vary depending upon the desired properties sought to be obtained by those skilled in the art utilizing the teachings disclosed herein. The use of numerical ranges by endpoints includes all numbers within that range (e.g., 1 to 5 includes 1, 1.5, 2, 2.75, 3, 3.80, 4, and 5) and any range within that range.

[0055] The various embodiments described above may be implemented using circuitry, firmware, and / or software modules that interact to provide particular results. One of skill in the art can readily implement such described functionality, either at a modular level or as a whole, using knowledge generally known in the art. For example, the flowcharts and control diagrams illustrated herein may be used to create computer-readable instructions / code for execution by a processor. Such instructions may be stored on a non-transitory computer-readable medium and transferred to the processor for execution as is known in the art. The structures and procedures shown above are only a representative example of embodiments that can be used to provide the functions described hereinabove.

[0056] Note that any components described herein using terms such as “processor,” “controller,” “logic circuit,” “CPU,” or the like may be implemented using a plurality of discrete units operating together. For example, a processor that performs a series of steps or operations may be construed as two or more processors operating cooperatively to perform the steps. Similarly, other processing hardware such as memory and input-output may perform the described functions with multiple discrete units operating cooperatively or being coordinated by another unit, e.g., by a central processor or processors.

[0057] The foregoing description of the example embodiments has been presented for the purposes of illustration and description. It is not intended to be exhaustive or to limit the embodiments to the precise form disclosed. Many modifications and variationsare possible in light of the above teaching. Any or all features of the disclosed embodiments can be applied individually or in any combination and are not meant to be limiting, but purely illustrative. It is intended that the scope of the invention be limited not with this detailed description, but rather determined by the claims appended hereto and equivalents thereof.

Claims

CLAIMSWhat is claimed is:

1. A work vehicle comprising:an electric work motor;a main battery operable to drive the electric work motor;a power distribution unit coupled to the main battery;a swappable accessory interface operable to electrically and mechanically couple an accessory battery to the work vehicle, wherein the power distribution unit comprises circuitry operable to change between a first mode and a second mode,the main battery providing charging energy to the accessory battery in the first mode, andthe accessory battery providing work energy that augments driving of the electric work motor in the second mode.

2. The work vehicle of claim 1, wherein the main battery is fixably mounted to the work vehicle.

3. The work vehicle of claim 1, wherein the main battery has a higher nominal voltage than a corresponding nominal voltage of the accessory battery.

4. The work vehicle of claim 1, wherein the swappable accessory interface is configured to electrically and mechanically couple a direct current (DC) connector to the work vehicle, the circuitry of the power distribution unit operable in a third mode wherein a DC charger charges the main battery via the DC connector coupled to the work vehicle.

5. The work vehicle of claim 4, wherein the DC charger comprises one of both of a solar cell and a battery array.

6. The work vehicle of claim 4, wherein the power distribution unit is operable in the third mode to prevent actuation of the electric work motor.

7. The work vehicle of any one of claims 1-6, wherein in the second mode, a discharge rate of the accessory battery is limited to less than half of a maximum discharge rate of the accessory battery.

8. The work vehicle of any one of claims 1-6, wherein in the second mode, a discharge rate or discharge current of the accessory battery is tied to a corresponding discharge rate or corresponding discharge current of the main battery.

9. The work vehicle of any one of claims 1-6, wherein the electric work motor is a traction motor.

10. The work vehicle of any one of claims 1-6, wherein the electric work motor is a work implement motor.

11. The work vehicle of any one of claims 1-6, wherein the work vehicle comprises any combination of a tractor, a mower, a front-end loader, fork lift, a greens roller, a material handler, and a compact utility loader.

12. The work vehicle of any one of claims 1-6, further comprising a user control that facilitates switching between the first mode and the second mode.

13. The work vehicle of any one of claims 1-6, wherein the power distribution unit is operable to detect, while operating in the first mode, that a state of charge of the main battery falls below a first threshold, and in response thereto, stop providing the charging energy to the accessory battery.

14. The work vehicle of claim 13, wherein the power distribution unit is operable to detect, while operating in the first mode, that a state of charge of the main battery falls below a second threshold, and in response thereto, switch to the second mode.

15. The work vehicle of any one of claims 1-6, wherein the accessory battery is operable to power a tool or machine separate from the work vehicle.

16. A circuit-implemented method comprising:detecting an accessory battery installed in a swappable accessory interface that electrically and mechanically couples the accessory battery to a work vehicle, the work vehicle comprising an electric work motor and a main battery operable to drive the electric work motor;detecting a user selection between a first mode and a second mode;in response to detecting selection of the first mode, providing charging energy from the main battery to the accessory battery; andin response to detecting selection of the second mode, providing work energy from the accessory battery to augment driving of the electric work motor.

17. The circuit-implemented method of claim 16, further comprising detecting a direct current (DC) charger electrically and mechanically coupled to the work vehicle, and in response thereto entering a third mode wherein the DC charger charges the main battery via a DC connector of the DC charger coupled to the swappable accessory interface.

18. The circuit-implemented method of claim 16, further comprising:detecting, while operating in the first mode, that a state of charge of the main battery falls below a first threshold; andin response thereto, stopping provision of the charging energy to the accessory battery'.

19. A system comprising:a portable ground maintenance tool or machine powered by a swappable accessory battery'; anda work vehicle comprising:an electric work motor;a main battery operable to drive the electric work motor;a power distribution unit coupled to the main battery; anda swappable accessory interface operable to electrically and mechanically couple the accessory battery to the work vehicle, wherein the power distributionunit comprises circuitry operable to provide charging energy to the accessory battery in a first mode.

20. The system of claim 19, wherein the circuitry of the power distribution unit is further operable to switch between the first mode and a second mode, the power distribution unit providing work energy from the accessory battery to augment driving of the electric work motor in the second mode.

21. The system of claim 19, wherein the portable ground maintenance tool or machine is carried in or by the work vehicle during work.

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