GB2412796A

GB2412796A - Power supply with rechargeable cell and voltage booster

Info

Publication number: GB2412796A
Application number: GB0419425A
Authority: GB
Inventors: Sheila Hamilton; Charles Jonathan Kennett
Original assignee: Teknek Electronics Ltd; Teknek Holdings Ltd
Current assignee: Teknek Holdings Ltd
Priority date: 2004-09-02
Filing date: 2004-09-02
Publication date: 2005-10-05
Also published as: GB0419425D0

Abstract

A battery powered device, for example a torch 10, is powered by one or more rechargeable batteries 20 acting through a voltage booster 22 which may be provided within a casing of the same size and shape as a battery. The voltage booster may replace one of the rechargeable batteries such that the device can use one less battery than would normally be required.

Description

24 1 2796 1 Power Suppl_ 3 The present invention relates to a power

supply, and 4 in particular to a method of powering a device, a power supply for a device and a device powered 6 according to the method and by the power supply.

8 Technological developments in the dry cell industry 9 have resulted in the power capacity of standard size dry cells (e.g. AA, AAA) rising many fold in the 11 last 20 years. This increase in charge capacity has 12 been a necessary requirement in the evolution of 13 ever more power hungry mobile devices.

The arrival of the rechargeable dry cell seemed to 16 herald great opportunities for cost saving and 17 enhanced battery life and seemed an entirely logical 18 step at a time when the world was becoming 19 increasingly aware of green issues, including disposal of spent batteries in landfill sites and 21 concern over disposal of heavy metals used in the 22 construction of modern batteries. Given these 1 factors, the transition to the rechargeable battery 2 cell seemed inevitable.

4 However, this has turned out simply not to be the case, for many reasons.

7 Firstly, a typical rechargeable battery actually 8 provides a slightly lower onload voltage than that 9 supplied by a standard battery. Some devices are particularly voltage sensitive, and so some 11 manufacturers advise against attempting to use 12 rechargeables in their devices, particularly when 13 the device needs to be powered by a large number of 14 batteries connected in series.

16 Also, the process of removing a rechargeable battery 17 from a device, inserting it into a charger, and then 18 having to remove it from the charger and re-insert 19 it into the device represents a significant amount of additional effort when compared with simply 21 removing and replacing a spent standard battery.

22 This problem of double handling is further 23 exacerbated by the tight fits between the battery 24 and the holders in the charger and the device.

Furthermore, a user of the device also faces the 26 task of ensuring that the polarity of the battery in 27 the charger is correct.

29 The double handling required when recharging batteries in a charger remote from the device in 31 which they are used only serves to underline the 1 fact that battery management has remained stagnant 2 all this time.

4 Therefore, there exists a need for a method of powering a device with rechargeable batteries that 6 provides an output voltage suitable for powering the 7 device, and for getting around the double handling 8 burden that exists with current rechargeable battery 9 solutions.

11 According to a first aspect of the present 12 invention, there is provided a method of powering a 13 device wherein a power supply included in the device 14 that is designed to hold at least two cells comprises instead at least one rechargeable cell and 16 a voltage booster, such that the power supply 17 produces sufficient voltage to power the device.

19 According to a second aspect of the present invention, there is provided a power supply for 21 powering a device comprising at least one 22 rechargeable cell and a voltage booster, which are 23 operable to supply a voltage to a device that would 24 correspond to that supplied by at least two cells.

26 According to a third aspect of the present 27 invention, there is provided a device powered in 28 accordance with the method of the first aspect, or 29 by a power supply according to the second aspect.

1 Preferably, the voltage produced is equivalent to 2 the voltage that would be produced if the regular 3 number of cells was used to power the device.

Preferably, the number of rechargeable cells 6 provided is one less than the number of cells that 7 the power supply is designed to hold.

9 The use of the voltage booster ensures that, when the device is used, the output voltage remains 11 substantially constant until the energy from the 12 rechargeable cells is completely used up. This is 13 in contrast to normal operation with a plurality of 14 cells, in which case the voltage gradually drops, resulting in a gradual deterioration of the power of 16 the device as the batteries fade.

18 Preferably, the device is further provided with 19 charging interface means adapted for use with charging means to charge the rechargeable cells in 21 situ.

23 The voltage booster may be comprised within a 24 housing that is dimensioned to have a similar size and shape to a rechargeable cell.

27 Preferably, the voltage booster includes a sleep 28 circuit which is adapted to turn the voltage booster 29 off when not required.

1 Embodiments of the invention will now be described, 2 by way of example only, with reference to the 3 drawings, in which: 4 Fig. 1 is a schematic perspective view of a torch forming one embodiment of the invention; 6 Fig. 2 is a circuit diagram for the torch of 7 Fig. 1; and 8 Fig. 3 is a schematic side view of a torch 9 forming an alternative embodiment.

11 There are many mobile devices which use multiples of 12 standard batteries, (e.g. double AA eta) arranged in 13 series so as to provide the required working 14 voltage.

16 For example, a torch operating on standard batteries 17 might use three cells inline to create a total 18 output voltage of 4.5 volts. Simply substituting 19 three commercially available rechargeable batteries in place of the originals would result in an output 21 voltage of only 3.6 volts compared to 4. 5, which 22 would lead to an associated loss of light output.

24 However, by replacing 1 of the cells with a voltage booster and using two rechargeable cells, the same 26 output voltage (4.5 volts) can be easily attained.

28 Clearly, by using fewer batteries there is less 29 space required in the device. There is also the 3 0 advantage that there is less weight in the battery 31 packs used for devices and also less batteries are 1 disposed of, thus creating less waste in the 2 environment.

4 The added advantage of using the voltage booster is that the output voltage remains more or less 6 constant until the energy from the rechargeable 7 cells is completely used up. This is in sharp 8 contrast to standard systems whereby the light of 9 the torch will gradually fade as battery voltage falls.

12 A sleep circuit is also included with the voltage 13 booster. The sleep circuit switches the voltage 14 booster off when the device does not require power, such as when the device (such as a torch) is 16 switched off. The switching off of the voltage 17 booster prevents the voltage booster draining the 18 power in the battery when the device is switched 19 off.

21 A voltage booster circuit is small scale, and does 22 not come in any particular size or shape. The 23 voltage booster circuit could be incorporated within 24 a housing having a shape mimicking the size and general dimensions of the cell which it has 26 replaced.

28 Fig. 1 shows an example of such an arrangement. A 29 torch 10 has a casing 12 including a body portion 14 and a head 16. The head 16 contains a bulb and 31 reflector (not shown). The body portion is 32 dimensioned to accept three cells, typically D 1 cells, but in this instance contains two D cells 20 2 and a voltage booster 22 contained in a casing of 3 the same size and shape as a D cell. Fig. 2 shows 4 the equivalent electrical circuit including a bulb 24.

7 This may be the case with all known sizes of 8 standard battery, including button cell or cellphone 9 batteries.

11 Alternatively, the voltage booster circuit is merely 12 connected to the rechargeable battery and is 13 included within the casing of the device (such as a 14 torch).

16 Fig. 3 shows an embodiment of this type. Similar 17 parts to those of Fig. 1 are shown by like reference 18 numerals. The bulb is seen at 24 and the reflector 19 at 26. The voltage booster 22a is formed as a fixed part of the torch body, interposed between the 21 batteries 20 and the head 16.

23 Furthermore, a simple socket could be made in the 24 end of the torch so that the batteries can be recharged without removal from the device, as shown 26 at 28 in Fig. 3..

28 Recharging of the batteries in situ could be carried 29 out by connecting a purpose built charge unit or, if applicable, a typical cell phone charger could be 31 used. This could be done, for example, if the torch 32 was a two cell device, enabling it to be charged by 1 a typical cell phone charger whose output may be 2 anywhere between 4.5 volts and 6.2 volts. The use 3 of non-specific chargers to charge the new device 4 enhances the portability of the product and reduces the cost of the conversion.

7 Low power voltage booster circuits are well known 8 per se and are therefore not described in detail 9 herein. The invention may conveniently use a voltage booster of the type using a high frequency 11 transformer with the input voltage switched to 12 provide a high frequency square wave, the 13 transformer output being rectified and smoothed to 14 provide the dc output voltage.

16 Therefore, a device that hitherto could not operate 17 satisfactorily on rechargeable batteries can not 18 only do so with ease but the batteries can be 19 recharged without removal from the device. Given that the handling of batteries has been a major 21 downside to the changeover to rechargeable 22 batteries, this is considered a major advantage 23 since handling is completely avoided.

Various improvements and modifications can be made 26 to the above without departing from the scope of the 27 invention.

Claims

1 CLAIMS 3 1. A method of powering a device wherein a power 4 supply

included in the device that is designed to hold at least two cells comprises instead at least 6 one rechargeable cell and a voltage booster, such 7 that the power supply produces sufficient voltage to 8 power the device.

2. A method according to claim 1, in which the 11 voltage produced is equivalent to the voltage that 12 would be produced if the regular number of cells was 13 used to power the device.

3. A method according to claim 1 or claim 2, in 16 which the number of rechargeable cells provided is 17 one less than the number of cells that the power 18 supply is designed to hold.

4. A method according to any preceding claim, in 21 which the voltage booster is comprised within a 22 housing that is dimensioned to have a similar size 23 and shape to a rechargeable cell.

5. A power supply for powering a device, 26 comprising at least one rechargeable cell and a 27 voltage booster, which are operable to supply a 28 voltage to a device that would correspond to that 29 supplied by at least two cells.

31

6. A power supply according to claim 5, in which 32 the voltage produced is equivalent to the voltage 1 that would be produced if the regular number of 2 cells was used to power the device.

4

7. A power supply according to claim 5 or claim 6, in which the number of rechargeable cells provided 6 is one less than the number of cells that the power 7 supply is designed to hold.

9

8. A power supply according to any of claims 5 to 7, further provided with charging interface means 11 adapted for use with charging means to charge the 12 rechargeable cells in situ.

14

9. A power supply according to any of claims 5 to 8, in which the voltage booster is comprised within 16 a housing that is dimensioned to have a similar size 17 and shape to a rechargeable cell.

19

10. A power supply according to any of claims 5 to 9, in which the voltage booster includes a sleep 21 circuit which is adapted to turn the voltage booster 22 off when not required.

24

11. A power supply according to any of claims 5 to 10, including charging interface means adapted for 26 use with charging means to charge the rechargeable 27 cells in situ.

29

12. A device powered in accordance with the method of claim 1, or by a power supply according to claim 31 5.

1

13. A method of powering a device, substantially as 2 herein described with reference to the drawings.

4

14. A power supply substantially as herein described with reference to the drawings.