Field of the Invention

The present invention relates to a power interface system for supplying power to a rechargeable battery and/or to a power consuming product.

Background of the Invention

The use of rechargeable batteries is well known, as well as the use of charging stations for charging the rechargeable batteries. Especially, rechargeable batteries used in portable tools, such as work light or handheld tools, are well known.

When using a charging station, the only function of the charging station is to charge rechargeable batteries. A rechargeable battery is often seen as a single unit with predefined size, which can be recharged in a charging station. There are charging stations capable of charging a multiple number of single units in predefined sizes of recharge- able batteries in different sizes. The batteries must fit into a battery housing prepared for the predefined size of the batteries. A rechargeable battery can be an external unit, which can be attached to a powered unit, e.g. a portable or handheld tool. This kind of rechargeable battery can be recharged through a charging station, which is intended for this exact type of rechargeable battery and the charging station follows one charg- ing sequence.

When using for example a portable powered unit, such as a work light or a handheld screwdriver, the work often stops because the rechargeable battery runs out of power while using the powered unit. Then the rechargeable battery needs to be charged. It takes time to charge the rechargeable battery, and another solution for powering the unit must be found, either by using another recharged battery of the same type, or if possible, by another power supply if the powered unit has the ability to be powered by other sources of energy than the rechargeable battery. Otherwise the work cannot continue. Object of the Invention

It is the object of the present invention to provide a power interface system suitable for recharging batteries and suppling power to power consuming products.

The present invention addresses the above mentioned problems and additionally pro- vides a number of further advantages.

Description of the Invention

The present invention addresses this by providing a power interface system for supplying power to different powered units, wherein said power interface system at least comprises a main power unit, a rechargeable unit and a powered unit.

The main power unit has a connection to a main power supply, and said main power unit comprises one or more sets of electrical terminals and first means for positioning and retaining said main power unit in electrical contact with either said rechargeable unit or said powered unit.

The rechargeable unit is provided with a set of electrical terminals and second means for retaining and positioning said rechargeable unit in electrical contact with either said main power unit or said powered unit. The powered unit has a set of electrical terminals and third means for positioning and retaining said powered unit in electrical contact with either said main power unit or said rechargeable unit.

The power interface system provides an agile and intelligent system for powering units. The power interface system consists of at least three units, a main power unit, a rechargeable unit and a powered unit. The main power unit has the double function of both a charging station and a power supply. The main power unit has a connection to a main power supply e.g. a cable. The power interface system can supply power to a powered unit through the main power unit or through the rechargeable unit. The re- chargeable unit can be a rechargeable battery. At the same time the power interface system is providing a system, where the rechargeable battery is charged from the same main power unit, which can also supply power to the powered unit. The main power unit is capable of supplying power to the powered unit through one set of electrical terminals, and charges the rechargeable battery through the same set or another set of electrical terminals simultaneously. The main power unit may also be capable of supplying power to the powered unit through a set of electrical terminals, and charges the rechargeable battery through the same set of electrical terminals. The powered unit may be a work light, a handheld or a portable tool and other electrical units etc.

The units of the power interface system may be provided with sliding parts and a locking mechanism with releasing features, so the units of the power interface system are able to maintain a constant position in relation to each other, and retaining the position during power transfer from one unit to another unit.

The power interface system comprises a main power unit, where the main power unit can operate one or more rechargeable batteries. The rechargeable battery can alternately be used in a wide range of different powered units. The powered units can be many different variants of portable powered products, provided for being powered through a main power unit or at least one rechargeable battery. The rechargeable battery is easily and quickly changed.

In an advantageous embodiment of the invention, the main power unit comprises two sets of electrical terminals, where said first means for positioning and retaining said main power unit in electrical contact is doubled, such that one set of electrical terminals is arranged with retaining and positioning means suitable to engage the rechargeable unit and the second set of electrical terminals is arranged with retaining and positioning means suitable to engage the powered unit.

The main power unit has a set of electrical terminals for powering the powered unit, and means for positioning and retaining the main power unit and the powered unit relative to one another. The main power unit also has a set of electrical terminals for charging the rechargeable unit, and means for positioning and retaining the main pow- er unit and the rechargeable unit to one another.

In a further embodiment version, the main power unit may be provided with only one set of electrical terminals prepared to supply power to the powered unit and for charging the rechargeable unit. The main power unit, having one set of electrical terminals, supplies either the powered unit or the rechargeable unit at a time and at the same time provides means for positioning and retaining the units together during the power transfer operation. In a further advantageous embodiment of the invention, the power interface system transfers power to the rechargeable unit and/or the powered unit, by using one or both of the following means: electrical terminals in direct electrical contact or electrical terminals in inductive contact. The electric contact between the main power unit, the powered unit and the rechargeable unit, can be inductive contact. By using an inductive transfer of power from one unit to another, the power is transferred without direct contact between the electrical terminals. The inductive transmission is useful to power electrical units where direct contact between electrical terminals is inconvenient, hazardous or not possible.

When using electrical terminals using direct or wired contact between the main power unit, the powered unit and the rechargeable unit, there will be apertures where the electrical terminals passes through the housing surface of the main power unit, the powered unit and the rechargeable unit. The apertures provide access from the ambi- ent surroundings into the internal electronical circuit inside the main power unit, the powered unit and the rechargeable unit. This provides an access for unwanted dirt, moisture and liquid to penetrate into the internal electronical circuit and in worst case destroy the internal electronical circuit. The surfaces of the main power unit, the powered unit and the rechargeable unit, when using an inductive transmission of power, can be sealed. When sealing the housing surface, the unwanted dirt, moisture and liquid cannot penetrate into the internal electronical circuit and be destructive.

One example may be that the environment wherein the power interface system is used may demand that the housing surface of all the power interface systems' units is easily cleaned, due to hygiene conditions and requirements therefor. The housing surface will be uniform and smooth, and therefore easily cleaned and maintainable.

The environment wherein the power interface system is used may also contain a degree of chemicals, which the power interface system is exposed to. The surface of the main power unit, the powered unit and the rechargeable unit, when using an inductive transmission of power, can be provided in a material where the power interface system has a resistant surface to the chemicals. Still the surfaces of the power interface system can be uniform and smooth, and easy to clean.

In a still further advantageous embodiment of the invention, the electrical terminals of said powered unit are attached directly on/in said powered unit or are connected by means of a wire to said powered unit. The powered unit can be a work light or another portable unit. In situations it may be preferred to have one or more work lights connected by cable or wire to a common main power unit or to one common rechargeable battery.

In a further advantageous embodiment of the invention, the main power unit compris- es a control unit, controlling the electrical settings of the terminals on the main power unit for a predetermined charging setting, used when charging the rechargeable unit, and to a predetermined power setting, used when powering the powered unit.

The internal electronical circuit, which is included in the main power unit, comprises a control unit, controlling the electrical settings of the electronical terminals on the main power unit. The predetermined electrical charging setting and also the charging sequence, used when charging the rechargeable unit, are for example depending on the type of rechargeable battery used in the power interface system. The predetermined power setting, used when powering the powered unit is depending on the chosen work light power consumption and how the power is supplied efficiently.

Also the internal electronical circuits in the powered unit and the rechargeable unit comprise a control unit. The control units in the main power unit, the powered unit and the rechargeable unit respectively are able to detect the other unit that they are connected to, and the communication is provided.

For example, when the main power unit is powering the powered unit as being a work light, the main power unit is in communication with the work light. The communication between the main power unit and the work light may be as follows: level of lumi- nous intensity, grades of viewing angle, working condition in respect to voltage and current, error detection etc. The main power unit can stop the power transferred to the work light if critical error occurs, such as short circuit in either the main power unit or in the work light.

Another example is, when the main power unit is charging the rechargeable unit as being a rechargeable battery, the main power unit is in communication with the rechargeable battery. The communication between the main power unit and the rechargeable battery may be as follows: predetermined charging setting, charging se- quence, working condition in respect to voltage and current, error detection etc. The predetermined charging setting and the charging sequence is for example based on the battery type and how the battery type inside the battery pack is connected. The battery type may be one of the following types: lead acid, nickel-cadmium, nickel-metal- hybrid or lithium-ion etc. The main power supply can differentiate the charging set- ting and the charging sequence depending on the rechargeable battery type and capacity before starting the charging sequence. The main power unit can stop the power transferred to the rechargeable battery if critical error occurs, such as short circuit in either the main power unit or in the rechargeable battery. An example is also when the powered unit being a work light is powered from a rechargeable unit being a rechargeable battery. At the same time the work light and the rechargeable battery are in communication with each other. The communication between the work light and the rechargeable battery may be the following: working condition in respect to voltage and current, critical power level, error detection etc. If the rechargeable battery has reached a critical power level and needs to be recharged, the power transfer from rechargeable battery to the work light is stopped. Also the rechargeable battery can stop the power transferred to the work light if critical error occurs, such as short circuit in either the rechargeable battery or in the work light. One or more sound units can also be provided to the power interface system. A sound unit can add a sound or different sounds if for example the following events occur: rechargeable battery reaches a critical power level and needs to be recharged, or if the work light has a critical error, or if the main power unit has a critical error, or if the main power unit detects a variation in the measured parameter from the work light or the rechargeable battery relation to the pre-settings, etc.

Through electronical communication means, the program and/or setting can be con- trolled and changed from an external computer unit. The main power unit, the powered unit and the rechargeable unit can therefore be reprogrammed and pre-settings can be changed.

In a still further advantageous embodiment of the invention, the main power unit, when the rechargeable unit and the powered unit is attached to the main power unit simultaneously, controls the power supplied from the rechargeable unit and transferring the power from the rechargeable unit to the power consuming product in lack of main power to the main power unit. If the main power unit has two electrical terminals, either electrical terminal with direct electrical contact or by inductive contact, the main power unit is capable of charging a rechargeable unit being a rechargeable battery, and at the same time providing power to a powered unit, such as a work light. If the main power unit is cut off from the main power supply, while the main power unit is charging the rechargeable battery and powering the work light, the main power unit will start powering the working light from the rechargeable battery, until the rechargeable battery reaches a critical power level or until the main power supply is restored.

In an advantageous embodiment of the invention, the main power unit, said rechargeable unit and powered unit are attachable to one another by using one or more of the following means: sliding parts, connecting parts, releasable locking parts. To maintain a constant position and retain the position during the power transfer between the main power unit, the rechargeable unit and the powered unit, sliding parts, connecting parts, releasable locking parts, are means to keep the units of the power interface system firm connected during use. The sliding parts are holding two or more of the units in the power interface system together in a firm grip. By sliding one part located in one unit into another part located in another unit, the electrical terminals are hold tighter and thereby securing that the electrical terminals are proper connected. The power transfer between the two units will be optimal with a high efficiency. This applies also when the transfer is inductive.

The power interface system, when connected, can be moved many times during use e.g. from one location to another. To keep the portable units of the power interface system connected together while using the units, the units must be firm connected or locked together. A locking mechanism with release feature can be provided, where one of the units includes one part of the locking mechanism and the other unit includes another part of the locking mechanisms where the two locking mechanism parts fit together when locked, and can be released. The locking mechanism may be a snap fit locking mechanism or a locking/spring pin. The units will then stay in the position until the locking mechanism is released.

Description of the Drawing

The invention will now be explained with reference to the accompanying drawings in which Fig. 1 : Illustrates a power interface system for supplying power to different units.

Fig. 2: Illustrates a main power unit and a work light, where the main power unit is connectable with the work light.

Fig. 3 : Illustrates a work light connected with a main power unit.

Fig. 4: Illustrates a rechargeable battery comprising two sets of electrical terminals. Fig. 5: Illustrates a main power unit, a rechargeable battery and a work light, where a main power unit is charging a rechargeable battery.

Fig. 6: Illustrates a rechargeable battery connected to a work light.

Fig. 7: Illustrates another version of the power interface system

Fig. 8: Illustrates a rechargeable battery used in a configuration according to fig.7. Fig. 9: Illustrates a work light used in a configuration according to fig.7.

Reference numbers:

1. Main power unit 2. Rechargeable battery

3. Work light

4. Main power cable

5. Electrical terminals placed on work light

6. Sliding member placed on work light

7. Sliding member placed on rechargeable battery

8. Electrical terminals placed for rechargeable battery

9. Electrical terminals placed for work light

10. Sliding member placed for work light

11. Sliding member placed for rechargeable battery

12. Electrical terminals for work light on rechargeable battery

13. Locking part

14. Electrical terminals placed on rechargeable battery

15. Stop member for rechargeable battery

16. Stop member for work light

17. Resilient locking part

18. Releasable part

Detailed Description of the Invention

Fig. 1 shows a power interface system for supplying power to different units. The power interface system comprises a main power unit (1), a rechargeable unit such as a rechargeable battery (2) and a powered unit such as work lights (3). The main power unit (1) has a connection to a main power supply through a main power cable (4). The main power unit (1) comprises one or more sets of electrical terminals placed on one side of the main power unit (1), which is not visual on the fig 1. The electrical termi- nals (5) on the work light (3) are provided in order to electrically connect the work light (3), from the main power unit (1) or the rechargeable battery (2).

The main power unit (1) comprises also first means for positioning and retaining the main power unit (1) in electrical contact with either the rechargeable battery (2) or the work light (3). The first means is placed on the same side as the electrical terminals on the main power unit (1). The main power unit (1) comprises a control unit, controlling the electrical settings of the terminals on the main power unit (1). The predetermined charging setting and also the charging sequence used when charging the rechargeable unit are depending on the type of rechargeable battery in use. The predetermined power setting, used when pow- ering the work light (3) is depending on the chosen work light' (3) power consumption, and how the power is supplied efficiently from the main power unit (1) to the work light (3).

Fig. 2 shows a main power unit (1) and a work light (3). The main power unit (1) is connectable with the work light (3). In order for the main power unit (1) to be in electrical contact with the work light (3), the electrical terminals (9) on the main power unit (1) are provided inside the main power unit (1) through slots. The main power cable (4) is attached in one end of the main power unit (1) and the slots containing the electrical terminals (9) are placed in the opposite end of the main power cable (4). The electrical terminals (5) on the work light (3) are provided as spears connectable with the electrical terminals' (9) slots provided on the main power unit.

The electrical terminals' (9) slots provided on the main power unit (1) and the electrical terminals' (5) spears provided on the work light (3) are arranged with retaining and positioning means (6, 10) suitable to engage in a steady position during use.

The electrical terminals (8) provided on the main power unit (1) are used when charging the rechargeable battery (2). The electrical terminals (8) are extended from the surface of the main power unit (1). The retaining and positioning means (11) are used when engaging the rechargeable battery (2).

The retaining and positioning means are sliding members (10, 11). The sliding members (10, 11) are placed parallel to one another. The two sliding members (10) are placed on opposite sides of the electrical terminals (9). The two sliding members (11) are placed on opposite sides of the electrical terminals (8). The sliding members (10) are positioned so that the sliding member (10) may be fitted into sliding members (6) forming a firm grip, pushing the electrical terminals' (9) slots over the electrical terminals' (5) spears, and thereby fixating the main power unit (1) to the work light (3). The main power unit (1) and the work light (3) will maintain a constant position in relation to each other, and retaining the position during power transfer.

Fig 3 shows a work light (3) connected with a main power unit (1). The main power unit (1) is transforming the main power supplied to a constant voltage or constant current, adapted for the use of driving the work light (3). The main power unit (1) is providing the power to the work light (3) through electrical terminals. The position is retained by using provided retaining and positioning means. The retaining and positioning means are keeping the electrical terminals in electrical contact during use, us- ing e.g. a sliding means and releasable locking mechanisms. The main power unit (1) is placed such that the surface of the main power supply flushes the surface of the work light (3).

Fig. 4 shows a rechargeable battery (2) that comprises two set of electrical terminals (12, 14). One set of the electrical terminals (12) on the rechargeable battery (2) is provided with slots, which are connectable with the spears of the electrical terminals (5) provided on the work light (3), showed in fig. 2. The other set of electrical terminals (14) provided on the rechargeable battery (2) is provided for the use of charging the rechargeable battery (2).

The retaining and positioning means as sliding members (7) are provided on the rechargeable battery (2) near the electrical terminals (14). The two sliding members (7) are placed parallel to one another and placed on opposite sides of the electrical terminals (14). The sliding members (7) are provided in order to keep the rechargeable battery (2) in position in relation to the main power unit (1) or the work light (3), and to retain the position, either when the rechargeable battery (2) is charged by the main power unit (1), or when the rechargeable battery (2) is powering the work light (3). The releasable locking mechanism (13) is provided on the rechargeable battery (2) keeping the rechargeable battery (2) in position during use.

Fig. 5 shows a main power unit (1), a rechargeable battery (2) and a work light (3), where the main power unit (1) is charging the rechargeable battery (2). The main power unit (1) is transforming the main power supplied by main power cable (4) to a constant voltage or constant current in a predetermined charging sequence, adapted for the use of the chosen rechargeable battery (2). The predetermined charging setting and the charging sequence is based on among other the battery type and the battery types inside the battery pack are connected. The battery type may be one of the following types: lead acid, nickel-cadmium, nickel-metal-hybrid or lithium-ion etc. The main power unit (1) is charging the rechargeable battery (2) by transferring power through the electrical terminals.

The position is retained by using the retaining and positioning means (7, 1 1) provided on the main power unit (1) and the rechargeable battery (2) respectively. The retaining and positioning means (7, 11) are keeping the electrical terminals in electrical contact during the charging process, using e.g. a sliding means and releasable locking mechanism. The sliding members (7, 11) are placed parallel to one another. The sliding members (1 1) are positioned so that the sliding member (11) can be fitted into sliding members (7) forming a firm grip and thereby fixating the main power unit (1) to the rechargeable battery (2). The main power unit (1) and the rechargeable battery (2) will maintain a constant position in relation to each other, and retaining the position during power transfer.

Fig. 6 shows a rechargeable battery (2) connected to the work light (3). The recharge- able battery (2) is provided with a set of electrical terminals, which are in electrical contact with the set of electrical terminals (5) of the work light (3), shown in fig 1. The electrical terminals transfer power from the rechargeable battery (2) to the work light (3). The rechargeable battery (2) is also provided with second means as sliding members (7) for positioning and retaining position, when the rechargeable battery (2) is in electrical contact with the work light (3). The sliding members (7) for positioning and retaining position of the rechargeable battery (2) are attachable to the third means being sliding members (6) for positioning and retaining the position of the work light (3). The work lights' (3) sliding members (6) and the rechargeable battery's (2) sliding members (7) are parallel to each other. The sliding members (7) on the rechargeable battery (2) are positioned so that the sliding member (7) may be fitted into sliding members (6) forming a firm grip, pushing the electrical terminals' (9) slots over the electrical terminals' (5) spears, showed in fig. 2, and thereby fixating the rechargeable battery (2) to the work light (3). Fig. 7 shows another version of the power interface system for supplying power to different units. The power interface system comprises a main power unit (1). The power interface system also comprises a rechargeable unit, such as a rechargeable battery (2) showed in fig. 8, and a powered unit, such as work lights (3) showed in fig. 9.

The main power unit (1) has a connection to a main power supply through a main power cable (4). The main power unit (1) comprises one or more sets of electrical terminals (8,9) placed on one side of the main power unit (1). The two sets of electri- cal terminals (8,9) showed on the main power unit (1) are provided in order to electrically connect the main power unit (1) to the rechargeable battery (2) through the electrical terminals (8) and respectively to the work light (3) through the electrical terminals (9). The electrical terminal (8) is placed in the opposite end of the electrical terminal (9).

The main power unit (1) comprises also first means for positioning and retaining the main power unit (1) in electrical contact with either the rechargeable battery (2) or the work light (3). The first means is placed on the same side as the electrical terminals on the main power unit (1). The retaining and positioning means are sliding members (10', 10") and the sliding members (Ι , Ι '), and placed on the same side on the main power unit (1) as the electrical terminals (8.9). The sliding members (10', 10") and the sliding members (11 ', 11 ") are placed parallel to one another along two opposite sides of the main power unit (1). The two sliding members (10', 10") are placed on opposite sides of the electrical terminals (8), and the two sliding members (1 1) are placed on opposite sides of the electrical terminals (8).

The shape of the sliding members (1 , 11 ") is formed so that the sliding member (1 , 1 ) can be fitted into sliding members (7', 7") on the rechargeable battery (2) showed on fig. 8. The sliding member (7', 1 ) and the sliding member (7", 11 ") form a firm grip, when pushing the electrical terminals' (8) slots over the electrical terminals' (14) spears placed on the rechargeable battery (2) showed on fig. 8, and thereby positioning and fixating the main power unit (1) to the rechargeable battery (2). Also the shape of the sliding members (10', 10") is formed so that the sliding member (10', 10') can be fitted into sliding members (6',6") on the work light (3) showed on fig. 9. The sliding member (ό', ΙΟ') and the sliding member (6", 10") form a firm grip, when pushing the electrical terminals' (9) spears into the electrical terminals' (5) slots placed on the work light (3) showed on fig. 9, and thereby positioning and fixating the main power unit (1) to the work light (3).

The main power unit (1) comprises a control unit, controlling the electrical settings of the terminals on the main power unit (1). The predetermined charging setting and also the charging sequence, used when charging the rechargeable battery (2), is depending on the type of rechargeable battery in use. The predetermined power setting used when powering the work light (3) is depending on the chosen work light's (3) power consumption, and how the power is supplied efficiently from the main power unit (1) to the work light (3).

Fig. 8 shows a rechargeable battery (2) used in the same power interface system configuration as the main power unit (1) as showed in fig. 7. The rechargeable battery (2) comprises two sets of electrical terminals (12, 14). One set of the electrical terminals (12) on the rechargeable battery (2) is provided with spears, which is connectable with the slots of the electrical terminals (5) provided on the work light (3), showed in fig. 9. The other set of electrical terminals (14) is provided with spears on the rechargeable battery (2), which is connectable with the slots of the electrical terminals (8) provided on the main power unit (1) showed in fig. 7. The rechargeable battery (2) is charged when the connection between the electrical terminals (8) on the main power unit (1) and the electrical terminals (14) on the rechargeable battery (2) is provided and in use.

The retaining and positioning means as sliding members (7', 7") are provided on the rechargeable battery (2) on the same side of the rechargeable battery (2) as the electrical terminals (12, 14). The two sliding members (7',7") are placed parallel to one an- other, and the sliding member (7') and the sliding member (7") are placed on opposite sides of the electrical terminals (14). The sliding members (7',7") are provided in order to keep the rechargeable battery (2) in position in relation to the main power unit (1) or the work light (3), and to retain the position. The position is retained while the rechargeable battery (2) is charged by the main power unit (1), or when the rechargeable battery (2) is powering the work light (3).

A stop member (15) is placed in the opposite end to the electrical terminals (12, 14) on the rechargeable battery (2). When attaching the rechargeable battery (2) to the main power unit (1), the stop member (15) will slide into a connection with the spears of the electrical terminal (9) on the main power unit (1) showed in fig. 7. This will stabilize the position of the rechargeable battery (2) when connected to the main power unit (1). A part of the releasable locking mechanism, a locking part (13), is provid- ed on the rechargeable battery (2) keeping the rechargeable battery (2) in a locked position during use.

Fig. 9 shows a work light (3) used in the same power interface system configuration as the main power unit (1) as showed in fig. 7 and the rechargeable battery showed in fig. 8. The electrical terminals (5) and the third means for positioning and retaining the work light (3) in electrical contact with either the main power unit (1) showed on fig. 7 or the rechargeable battery (2) showed on fig. 8, are provided on the back side of the work light (3). At the front side the light is emitting from the work light's (3) integrated light source.

The work light (3) comprises a set of electrical terminals (5). The electrical terminals (12) on the work light (3) are provided with slots. The electrical terminals (12) are connectable with the electrical terminals (9) provided on the main power unit (1), showed in fig. 7 and the electrical terminals (12) provided on the rechargeable battery (2). The work light (3) is powered directly from the main power unit (1) when the connection between the electrical terminals (9) on the main power unit (1) and the electrical terminals (5) on the work light (3) is provided.

The work light (3) is powered directly from the rechargeable battery (2), when the connection between the electrical terminals (12) on the rechargeable battery (2) and the electrical terminals (5) on the work light (3) is provided.

The retaining and positioning means as sliding members (6', 6") are provided on the work light (3) on the back side of the work light (3), which is the same side as the electrical terminals (5). The two sliding members (6',6") are placed parallel to one another, and the sliding member (6') and the sliding member (6") are placed on opposite sides of the electrical terminals (5). The sliding members (6',6") are provided in order to keep the work light (3) in a position in relation to the main power unit (1) or the work light (3), and to retain the position during use. The position is retained while the work light (3) is powered by the main power unit (1) or powered by the rechargeable battery (2).

When sliding the rechargeable battery (2) into the fixated position in relation to the work light (3), the shape of the sliding members (6',6") is formed so that the sliding member (6',6') can be fitted together with the sliding members (7',7") on the rechargeable battery (2) showed on fig. 8. The sliding member (6',7') and the sliding member (6", 7") form a firm grip, when pushing the electrical terminals' (12) spears into the electrical terminals' (5) slots placed on the work light (3) thereby positioning and fixating the rechargeable battery (2) to the work light (3).

The shape of the sliding members (10', 10") placed on the main power unit (1), showed on fig. 7, is formed so that the sliding member (10', 10') can be fitted into sliding members (6',6") on the work light (3). The sliding member (ό', ΙΟ') and the slid- ing member (6", 10") form a firm grip, when pushing the main power unit's (1) electrical terminals' (9) spears, showed in fig. 7, into the electrical terminals' (5) slots on the work light (3), and thereby positioning and fixating the main power unit (1) to the work light (3). A stop member (16) is placed in a predefined distance to the electrical terminals (5) on the back side of the work light (3). When attaching the rechargeable battery (2) or the main power unit (1) to the work light (3), the stop member (16) will act as a backstop. The spears on the main power unit's (1) electrical terminals (9) or the rechargeable battery's (2) stop member (15) connect with the stop member (16) of the work light (3). When using the sliding members and the stop members when attaching two units together, the units are in a firm fixation and keep the position during use.

Furthermore, when attaching two units from the power interface system, a releasable locking mechanism is preferred, keeping the units together until the lock is unlocked. The work light (3) comprises a resilient locking part (17) and a release mechanism (18). When attaching the rechargeable battery (2) or the main power unit (1) to the work light (3), the resilient locking part (17) on the work light (3) is clicking into the locking part (13) of the rechargeable battery (2), showed in fig. 8, or the locking part (13) of the main power unit (1), showed in fig. 7. When the rechargeable battery (2) or the main power unit (1) is in a locked position on the back side of the work light (3), the rechargeable battery (2) or the main power unit (1) cannot be removed from the locked position. If the rechargeable battery (2) or the main power unit (1) is to be removed from the locked position, the locking mechanism must be unlocked by releas- ing the resilient locking part (17) from the locking part (13). The releasable part (18) is a button. When the button is pressed down, the resilient locking part (17) moves downwards and thereby is released from the locking part (13). The attached units can then be removed from each other.