GB1572713A - Connection arrangment for a rechargeable battery - Google Patents

Description

(t1) CONNECTION ARRANGEMENT FOR A RECHARGEABLE BATTERY (71) We. THE HORSTMANN GEAR COMPANY LIMITED, A British Company. of Newbridge Works. Bath BA1 3EF, Somerset, do hereby declare the invention.

for which we pray that a patent may be granted to us, and the method bv which it is to be performed, to be particularly described in and bv the following statement: This invention relates to connection arrangements for rechargeable batteries.

When rechargeable batteries are removably connectible in a power supply arrangement or in an electrical apparatus and are arranged to be rechargeable in situ damage can occur to circuits fed from the arrangement during recharging if the battery becomes disconnected. This invention seeks te reduce the risk of damage tc such circuits upon disconnection of the battery.

According to the invention there is provided a connection arrangement for use with a rechargeable battery for connecting the battery to its load and to a recharging system. comprising a first contact connected to a charging line and a second contact connected to a load connection line. the two contacts being arranged relative to the intended position of the battery such that, when in use with a battery, contact is made between the charging line. the load connection line and a terminal of the battery but when the battery is removed contact between the charging line and the load connection line is broken.

In a preferred version of the invention. a third contact is connected to a second charging line and a fourth contact, spaced from the third contact, is connected to a second load connection the third and fourth contacts being arranged such that, in use. a conductive path between the second charg ing and second load connection lines and a second terminal of the battery is completed onlv when a battery is inserted.

In one advantageous form the contact spacing is arranged such that upon insertion of a battery the contacts are bridged by the terminal(s) of the battery.

In order that the invention and its various other preferred features may be understood more easily. embodiments thereof will now be described, by way of example only, with reference to the drawings, in which: Figure 1 shows a known circuit arrangement for connection of a source of supply to a rechargeable battery and the battery to a load.

Figzo e 2 shows schematically a connection arrangement in accordance with the invention, and Fi,?t!-e 3 shows schematically an alternative connection arrangement in accordance with the invention.

The drawing of Figure 1 shows a conventional battery connection arrangement in which a pair of input lines 10 and 11 are connectible to an alternating current charging source. The line 10 is connected via a diode 12 to one terminal of battery 13. The line 11 is connected directly to another terminal of the battery 13. A load 14 is connected across the terminals of the cell by means of output lines 15 and 16. The battery is removable and if it becomes disconnected no permanent damage is normally done to loads having a large thermal inertia because the heating effect of peaks in the charging voltage can easily be absorbed. However, now that integrated circuits of minute thermal inertia have to be supplied by rechargeable cells. even one half cycle of excess voltage can cause irreparable damage. This excess voltage normally is easily absorbed by the rechargeable battery and only the battery voltage is applied to the load. but if the rechargeable battery becomes disconnected. or has a high resistance connection to the source of supply, the solid state load can be destroved or damaged.

One way of safeguarding the load which is known to us is to put a Zener diode across it which normally carries little current but if the voltage rises it takes so much current that in conjunction with the resistance of the supply circuit it reduces the peak voltages to values which the integrated circuit can tolerate. These Zener diodes are relatively costly.

Figure 2 shows one possible arrangement in accordance with the invention in which the input line 10, which is fed from one side of the secondary winding of a mains transformer 17. is coupled to the positive pole 22 of a battery 13 via a diode 12 and a contact 21. An output line 15 is coupled to the same positive pole 22 of the battery by means of a contact 20 which engages the positive pole but is spaced from the contact 21. A similar arrangement is provided for the input line 11 and output line 16 which are coupled to the negative pole 23 of the battery by means of contacts 24 and 25 respectively which in this case engage the negative pole but are mutually spaced. The output lines 15 and 16 are coupled to loads which in this case are shown to comprise the parallel arrangement of a resistive load 14 and an integrated circuit 26.

The contacts 21. 20. 25 and 25 are resiliently urged into conductive contact with their respective battery terminals and may be formed for example of springy metal strip. It will be appreciated that insertion of the battery effects completion of a conductive path between input and output lines 10/15 and 11/16 and effects contact of these lines to the battery terminals. Disconnection of the battery or a faulty connection. e.g. a high resistance between any one of the contacts and its respective terminal prevents the charging voltage from being developed across the load and prevents damage to the load.

An alternative arrangement is shown in Figure 3. In this arrangement one of the contacts 31/32, 34/35 of each inputloutput line is resiliently urged out of contact with the other contact to provide a spacing therebetween in the absence of a battery 13 but are urged into mutual contact upon insertion of the battery to complete the circuit between input lines 10 and 11 and output lines 15 and 16 respectively and to the respective positive and negative poles 22 and 23 of the battery when the battery is inserted. The contacts again may be formed of springy metal strip. This arrangement is less reliable than that of Figure 2 in that a bad contact between one contact and a terminal of the battery can result in an undesirable voltage reaching the load, however this condition is less likely to arise than the condition where the battery is removed or dislodged and accordingly provides a possible alternative arrangement suitable for some applications.

Although the embodiments described employ two mutually spaced contacts for each battery terminal it will be appreciated that such a contact arrangement could be provided on a single one of the battery terminals.

The main advantages of this arrangement are that it is simpler and hence more reliable than the Zener diode arrangement and of course cheaper.

WHAT WE CLAIM IS: 1. A connection arrangement for use with a rechargeable battery for connecting the battery to its load and to a recharging system, comprising a first contact connected to a charging line and a second contact connected to a load connection line, the two contacts being arranged relative to the intended position of the battery such that, when in use with a battery, contact is made between the charging line, the load connection line and a terminal of the battery but when the battery is removed contact between the charging line and the load connection line is broken.

2. A connection arrangement as claimed in Claim 1, wherein a third contact is connected to a second charging line and a fourth contact spaced from the third contact is connected to a second load connection line, the third and fourth contacts being arranged such that, in use, a conductive path between the second charging and second load connection lines and a second terminal of the battery is only completed when a battery is inserted.

3. A connection arrangement as claimed in Claim 1 or 2, wherein the contact spacing is arranged such that, upon insertion of a battery, the contacts are bridged by the terminal(s) of the battery.

4. A connection arrangement as claimed in Claim 1 or 2, wherein one of the contacts in the or each pair of charging/load lines is resiliently biased into the spaced apart position and is arranged to be urged into contact with the other contact against said bias upon insertion of a battery.

5. A connection arrangement for a rechargeable battery as claimed in any preceding claim including rectifying means in the or each charging line to permit charging of the battery from an alternating current supply.

6. A connection arrangement as claimed in Claim 5 including voltage transforming means feeding the charging line(s) and effective to provide a voltage for rectification by said rectifying means suitable for recharging a battery.

7. A connection arrangement for use with a rechargeable battery and substantially as described herein with reference to Figures 2 or 3 of the drawings.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims (8)

**WARNING** start of CLMS field may overlap end of DESC **. known to us is to put a Zener diode across it which normally carries little current but if the voltage rises it takes so much current that in conjunction with the resistance of the supply circuit it reduces the peak voltages to values which the integrated circuit can tolerate. These Zener diodes are relatively costly. Figure 2 shows one possible arrangement in accordance with the invention in which the input line 10, which is fed from one side of the secondary winding of a mains transformer 17. is coupled to the positive pole 22 of a battery 13 via a diode 12 and a contact 21. An output line 15 is coupled to the same positive pole 22 of the battery by means of a contact 20 which engages the positive pole but is spaced from the contact 21. A similar arrangement is provided for the input line 11 and output line 16 which are coupled to the negative pole 23 of the battery by means of contacts 24 and 25 respectively which in this case engage the negative pole but are mutually spaced. The output lines 15 and 16 are coupled to loads which in this case are shown to comprise the parallel arrangement of a resistive load 14 and an integrated circuit 26. The contacts 21. 20. 25 and 25 are resiliently urged into conductive contact with their respective battery terminals and may be formed for example of springy metal strip. It will be appreciated that insertion of the battery effects completion of a conductive path between input and output lines 10/15 and 11/16 and effects contact of these lines to the battery terminals. Disconnection of the battery or a faulty connection. e.g. a high resistance between any one of the contacts and its respective terminal prevents the charging voltage from being developed across the load and prevents damage to the load. An alternative arrangement is shown in Figure 3. In this arrangement one of the contacts 31/32, 34/35 of each inputloutput line is resiliently urged out of contact with the other contact to provide a spacing therebetween in the absence of a battery 13 but are urged into mutual contact upon insertion of the battery to complete the circuit between input lines 10 and 11 and output lines 15 and 16 respectively and to the respective positive and negative poles 22 and 23 of the battery when the battery is inserted. The contacts again may be formed of springy metal strip. This arrangement is less reliable than that of Figure 2 in that a bad contact between one contact and a terminal of the battery can result in an undesirable voltage reaching the load, however this condition is less likely to arise than the condition where the battery is removed or dislodged and accordingly provides a possible alternative arrangement suitable for some applications. Although the embodiments described employ two mutually spaced contacts for each battery terminal it will be appreciated that such a contact arrangement could be provided on a single one of the battery terminals. The main advantages of this arrangement are that it is simpler and hence more reliable than the Zener diode arrangement and of course cheaper. WHAT WE CLAIM IS:

1. A connection arrangement for use with a rechargeable battery for connecting the battery to its load and to a recharging system, comprising a first contact connected to a charging line and a second contact connected to a load connection line, the two contacts being arranged relative to the intended position of the battery such that, when in use with a battery, contact is made between the charging line, the load connection line and a terminal of the battery but when the battery is removed contact between the charging line and the load connection line is broken.

2. A connection arrangement as claimed in Claim 1, wherein a third contact is connected to a second charging line and a fourth contact spaced from the third contact is connected to a second load connection line, the third and fourth contacts being arranged such that, in use, a conductive path between the second charging and second load connection lines and a second terminal of the battery is only completed when a battery is inserted.

3. A connection arrangement as claimed in Claim 1 or 2, wherein the contact spacing is arranged such that, upon insertion of a battery, the contacts are bridged by the terminal(s) of the battery.

4. A connection arrangement as claimed in Claim 1 or 2, wherein one of the contacts in the or each pair of charging/load lines is resiliently biased into the spaced apart position and is arranged to be urged into contact with the other contact against said bias upon insertion of a battery.

5. A connection arrangement for a rechargeable battery as claimed in any preceding claim including rectifying means in the or each charging line to permit charging of the battery from an alternating current supply.

6. A connection arrangement as claimed in Claim 5 including voltage transforming means feeding the charging line(s) and effective to provide a voltage for rectification by said rectifying means suitable for recharging a battery.

7. A connection arrangement for use with a rechargeable battery and substantially as described herein with reference to Figures 2 or 3 of the drawings.

8. An electrical apparatus operable by a

rechargeable battery and having a battery connection as claimed in any preceding claim.