WO1979000617A1

WO1979000617A1 - A battery separator

Info

Publication number: WO1979000617A1
Application number: PCT/SE1978/000050
Authority: WO
Inventors: D Pettersson
Original assignee: D Pettersson
Priority date: 1978-02-13
Filing date: 1978-10-04
Publication date: 1979-09-06
Also published as: GB2036468B; EP0014696A1; SE7908323L; GB2036468A

Abstract

A battery separator for controlling the charging current from a generator (1) to a parallel combination of at least two battery members (2, 3) which are capable of being loaded individually. A sensing element (6) senses the charging current of the generator. A normally open switch is connected in one branch of the parallel combination in series with the battery member (2) of this branch. A control circuit connected to the sensing element closes the switch (7) when the charging current reaches a first predetermined value and opens the switch when the charging current falls below a second predetermined value, respectively. The battery separator permits optimum charging of the batteries of the parallel combination but, as soon as the charging ceases, prevents loading of one battery when the other is being loaded.

Description

A Battery Separator • Technical Field ..

The present invention refers to a battery separator which permits simultaneous charging of at least two storage batteries. When charging is not going on the battery separator has to separate the batteries so that each battery can be loaded separately without the remaining batteries being subjected to loading. Prefer¬ ably, the battery separator is utilized in connection with, for example, recreational boats, caravan-motor car combinations etc. equipped with two separate sto¬ rage batteries.

Background

Battery separators are known. For example, in a recrea¬ tional boat it may be advisable, from a safety point of view, to have two storage batteries separated from each other, one for motor starting and one for the remaining consumptions. Both batteries are to be charged simulta¬ neously by the existing generator. On the other hand, one battery has to be capable of being loaded without the other also being loaded. With the prior battery separator this is effected by means of two diodes which permit the charging current from the generator to pass to the two batteries through one diode each. However, the diodes pre¬ vent current from passing from one battery to the other, or vice versa. The batteries are said to be capable of be¬ ing loaded individually. Yet, this prior solution results in the disadvantage that the charging of the batteries is impaired on account of the unavoidable forward voltage drop in the diodes. Accordingly, the batteries will never have the possibility of being charged to their full capa¬ city.

In earlier types of generators this forward voltage drop

OMPI y_Λ_ WIPO could be compensated by actuating the voltage regulator so that the generator produced a correspondingly higher charging voltage. In to-day's generators, however, the regulator is often built into the generator housing whic complicates and in many cases precludes actuation of the regulator ifself.

Disclosure of Invention

The battery separator according to the present invention is based on a new principle and has a negligible voltage drop and, therefore, permits optimum charging of the bat teries. The battery separator according to the invention is intended for controlling the charging current from a generator to a parallel combination of at least two bat¬ tery members which are capable of being loaded individu- ally. The invention is characterized by a sensing elemen responsive to the charging current of the generator, a normally open switch which in one branch of the parallel combination is connected in series with an associated battery member, -and a control circuit connected to the sensing element for closing and opening, respectively, the switch when the charging current exceeds a first pre determined value and passes below a second predetermined value, respectively.

The battery separator permits optimum charging of the batteries of the parallel combination but prevents, as soon as the charging ceases, loading of one battery when the other is being loaded.

Brief description of Drawings

Figure 1 shows a circuit diagram of a prior battery sepa rator. Figure 2 shows a fundamental circuit diagram of a battery separator according to the present invention, an

"BU

O

' w Figure 3 shows a detailed circuit diagram of the battery separator according to the invention.

Best mode of carrying out the Invention

The prior battery separator mentioned in the introduction is shown in Figure 1 and includes a generator 1 connected in series with a parallel combination of two batteries 2 and 3, respectively. In either branch of the parallel com¬ bination there is connected a diode 4 and 5, respectively, the function of which is to prevent discharge of one bat- tery, for example 2, when the other, i.e. 3, is being dis¬ charged. However, diodes 4 and 5 permit simultaneous charging of both batteries from the generator. The forward voltage drop across either diode is typically 0.7 to 1 volt, which is sufficient for preventing optimum charging of each battery.

Figure 2 shows a fundamental diagram of the battery separa¬ tor according to the present invention. In the same way as in Figure 1 batteries 2 and 3 are included in a parallel combination to be charged by generator 1. A sensing element 6 senses the charging current from the generator. A switch 7 is connected in series with battery 2 in one branch of the parallel combination. A control circuit 8 operates switch 7 in response to the charging current. When the charging current exceeds a first predetermined value, the normally open switch 7 is closed and both batteries are charged in parallel. When the charging current decreases below a second predetermined value, the control circuit 8^' returns switch 7 to its normally open position. Said se¬ cond value is less than the first one and is due to hyste- resis characteristics of the sensing element 6. To prevent a condition of uncontrolled opening and closing of contact 7 and to force the switch, instead, into occupying either the closed or the open condition, this hysteresis characte- ristic of the sensing element is utilized, and besides a break delay may be introduced between the moment at which said second predetermined value is no longer reached and switch 7 opens. The break delay may be of the magnitude of 0.5 to 1 second.

Suppose that generator 1 begins to rotate. The output vo tage of the generator rises so as gradually to reach such a value that battery 3 will begin taking up charge. When the charging current has reached the predetermined first value switch 7 closes whereby battery 2 will also begin taking up charge. It is important to note that the sensing element senses the charging current and not the charging voltage, for if the switch should close when th output voltage from the generator reaches- a certain valu but the charging current has not yet begun flowing, then battery 2 would be connected in parallel with battery 3, battery 2 being loaded in parallel with battery 3 and pe haps in the worst case completely consumed, which in a c se where battery 2 is, for example, the starting battery of a boat while battery 3 is connected to the remaining consumers of the boat makes repeated motor starting impo sible.

Figure 3 shows a detailed circuit diagram of the battery separator according to the present invention. The sensin element 6 consists of two components, viz. a current coi 9 which is connected in series between the generator and the battery parallel combination and which accordingly i applied to the plus pole of the system. The other compo¬ nent of the sensing element consists of a blade element 10 which is arranged centrally within the current coil 9 The blade element 10 which usually includes two magnetic contact blades enclosed in a glass tube is activated and y its contact blades make contact with each other when the magnetic field in the, current coil 9 produced by the

O charging current amounts to the first predetermined va¬ lue which is determined by the product of the charging current and the number of turns of the current coil 9.

The control circuit 8 includes a relay having a relay coil 11 and a normally open make contact which forms the switch 7. In this specification, by a normally open make contact or a normally open switch is meant that the con¬ tact is open when the relay coil is without current. At its one end the relay coil 11 is connected to one end of the current coil 9, at which end also one contact bla¬ de of the blade element 10 is connected. The other end of the relay coil is connected to the collector of a tran¬ sistor 12. The emitter of the transistor is connected to the minus pole of the system. The other contact blade of the blade element is connected via resistors 13 and 14 to the base of the transistor 12. The common point between the resistors 13 and 14 connected in series is connected to one plate of a condenser 15, the other plate of which is connected to the minus pole of the system. The combi- nation of resistor 14 and condenser 15 forms - cut-out time delay network having the time constant 0.5 to 1.0 se¬ conds. A diode 16 is connected in parallel across the re¬ lay coil to protect the transistor against voltage tran¬ sients.

The transistor 12 is normally non-conducting. When the charging current in the current coil 9 rises to the first predetermined value the magnetic field in the current coil increases until the blade element closes, whereby the voltage rises on the base of the transistor and transis- tor 12 begins conducting, current passing through the re¬ lay coil 11. The relay is energized and closes the normal¬ ly open switch 7. Battery 2 is then connected in parallel with battery 3 and is charged together with the latter. When the charging current of the generator subsequently falls below said second predetermined value the magnetic field in the current coil 9 is no longer able to hold .. the contacts of the blade element closed. The blade ele- ment opens and condenser 15 is. discharged through resis¬ tor 14 and the base-emitter junction of transistor 12, and with a certain time delay the transistor cuts off, the relay being de-energized and the switch opening.

Suppose that during the driving of the vehicle battery 3 is being charged to an optimum. If battery 2 is poorly charged charging current will still pass through switch 7 until battery 2 is charged to an optimum and the sum of the charging currents through the batteries is below said second value, the relay being de-energized and the switch opening.

In figure 3 the common point between the relay coil 11 an one contact blade of the blade element 10 is shown to be_. connected to one end of the current coil 9. Said common point may just as well be connected to the other side of the current coil 9.

The following list shows the component values of the bat¬ tery separator according to the invention:

1. Generator; charging voltage about 14 Volt

2,3. 12 V batteries of the lead accumulator type 9. about 20 turns of 2.5 mm enamel coated copper wi

10. . Blade element which closes at about 30 ampere- turns and breaks at about 20 ampere-turns

11, 7 Relay for 12 Volts voltage and maximum 50 Am¬ pere breaking current 12. . Transistor, e.g. BC 337/25 or an equivalent 13. Resistor 47-T , 1/4 Watt 14. Resistor 33 k _Λ- , 1/4 Watt

15. Condenser 47 i , 40 Volt

16. Diode 1N4003 or an equivalent

Although it has not been shown in the drawings, it is to be understood that in parallel across either battery any desired number of consumers may be connected.

Furthermore, it is apparent that in the case where relay 11 has an additional normally open make contact, marked by dashed lines with the reference numeral 17 in Figure 3, the battery separator may be utilized for connecting an additional battery group, marked by the reference nume¬ ral 18, simultaneously with the connection of the batte-. ry group 2. The battery group 18 may, for example, consist of an extra reserve battery.

Industrial applicability

The battery separator may advantageously be utilized in caravan-motor car combinations and in boats equipped with several batteries to secure a high starting preparedness. ^•In the case of caravan-motor car combinations battery 3 preferably is the motor car battery while battery 2 is the battery of the caravan. In the .case of boats, batte¬ ry 2 preferably is the starting battery while battery 3 is used for the remaining consumers.

The above-described embodiment of the invention may be modified and varied in many ways within the scope of the basic conception of the invention.

Claims

- Claims

1. A battery separator for controlling the charging cur¬ rent from a generator (1) to a parallel combination of at least two battery members (2,3) which are capable of being loaded individually, characterized by a sensing element (6) responsive to the charging current of the generator, a normally open switch (7) which in one branc of the parallel combination is connected in series with an associated battery member (2) , and a control circuit (8). connected to the sensing element for closing and opening, respectively, the switch (7) when the charging current exceeds a first predetermined value and passes below a second predetermined value, respectively.

2. A battery separator according to claim 1, characteriz by the fact that the sensing element includes a current coil (9) connected in series between the generator (1) and the parallel combination (2,3) and a blade element (10) provided in the current coil (9) .

3. A battery separator according to claim 1 and/or 2, characterized by the fact that the control circuit (8) i cludes a relay having a coil (11) , the operating current of which is controlled by the sensing element, and also having a< normally open- make contact which consists of said switch (7) .

4. A battery separator according to claim 3, characteriz by a controlled amplifier member (12) having a control electrode connected to the output of the sensing element a first electrode (e.g. collector) connected to one end of the relay coil (11) and a second electrode (e.g. emit ter) connected to the minus pole of the parallel combina tion, the other end of the relay coil being connected to one end of the current coil (9) , to which end the input the sensing element is also connected.

5. A battery separator according to claim 4, characterized by a cut-out delay circuit (14,15) connected between the control electrode and said minus pole for delaying the ^• cut-out of the amplifier member counted in relation to the time when the charging current from the generator falls below the second predetermined value.