WO1990012427A1

WO1990012427A1 - Energy monitor for storage cells

Info

Publication number: WO1990012427A1
Application number: PCT/AU1990/000123
Authority: WO
Inventors: Tellio Joseph Grilli
Original assignee: Tellio Joseph Grilli
Priority date: 1989-03-30
Filing date: 1990-03-30
Publication date: 1990-10-18

Abstract

An energy monitor for a storage cell is located between the cell and a system drawing energy from the cell. The unit monitors parameters such as load, environment, discharge current, charging current which enables the provision of safe residual energy for emergency uses, and to provide safe working conditions for the cell. Preferably, there is a second cut-off point to prevent deep discharge of the cell, thereby maximizing cell life.

Description

TITLE: ENERGY MONITOR FOR STORAGE CELLS

This invention relates to storage cells, such as batteries or accumulators, and in particular relates to the monitoring of energy in relation to such cells.

It is a common occurrence for motorists to 'flatten' the battery (accumulator) of their car, usually by leaving the parking lights on. In order to start the car - if it has automatic transmission or cannot otherwise be 'roll started' - it is necessary to supply electrical energy from another car, using 'jumper leads' or from another source of energy. This involves seeking assistance from a friend or neighbour, or from a motoring service organisation.

It has been proposed to provide - in effect - a 'reserve' electric energy capacity in a battery, by which upon operation of a switch the car's engine may be started. A major disadvantage of this arrangement is the need to purchase a new - and expensive - battery. In one respect, it is an object of this invention to provide an arrangement for overcoming this problem.

The invention provides an energy monitor unit for a storage cell, said unit being adapted to monitor parameters associated with said cell and being adapted to initiate certain action as a result of charges in said parameters.

Conceptually, the energy monitor unit of the present invention monitors and acts upon the energy level, energy output and energy input of a storage cell, in particular a secondary storage cell. It will monitor energy extracted from the cell and energy returned thereto.

The unit will also make decisions based on environmental factors and manufacturers recommendations so as to provide an energy reserve for emergency use (such as that described hereinbefore in relation to a vehicle flat battery) and optimize the service life and safety of the cell. This will increase safety and maximize the economic life of the energy cell in a variety of applications.

Preferably, the unit will monitor the following parameters associated with battery applications:

1. Ambient Temperature

2. Charge Currents

3. Discharge Currents

4. Cell Voltage

Preferably, the unit will monitor the load, environment, discharge and the charging current to provide safe working conditions, and a cut-off point to provide a safe residual energy in the cell. This can then be used to provide an emergency supply (with a manual override to re-connect the cell in the vehicle application) whereby the unit will have a secondary energy cut-off point. This secondary point is designed to provide an optimum life of the cells by avoiding deep discharge as specified by the manufacturer's recommended operating condition for the cells (batteries). By doing so the unit will reduce the likelihood of hydrogen and oxygen gas production that can occur when unchecked charging currents are passed to the cell.

The benefits will be to provide a longer service life of the cells and a safer application by reducing the gas producing conditions. By monitoring the charging system the unit will also assist in providing a safe guard of the charging system. This is done by giving a visual indication of the status of the charging system.

The unit will preferably have switch settings to adapt the cell (battery) characteristics to the application environment:

1. Nominal voltage of battery set

2. Type of battery (sealed or wet)

3. Stationary or mobile application

4. Ampere-Hour capacity of the battery set

5. Ampere rating of the charging or rectifier unit

6. External temperature setting/sensor

7. Average or peak temperature from external sensor

8. Temperature cell voltage compensation

9. Maximum discharge current

10. Recommended maximum charge current

11. Electrolyte type (lead-acid or nickel cadmium)

These variables will enable the unit to be customized to a variety of applications. The sorts of application that the unit can be used in include:

* Automotive Battery Monitoring, as hereinbefore discussed

* Agricultural Battery Monitoring

* Stationary batteries used in commercial areas: - PABXs

- uninterruptable power supplies

- generator using backup batteries

* Electrically powered vehicles

* Remote areas requiring secondary energy sources

* Stationary batteries used in industry and educational areas * Military vehicles

* Larger battery-powered toys

* Mining areas, either above or below ground

* Emergency lighting applications using backup batteries

The unit will preferably also have available a radio link that will enable remote transmission of alarm and status information at a distance. This feature is expected to be most useful in remote or mining areas, and in certain high security areas. An additional option for the unit is the use of a hydrogen gas sensor. This would be useful in confined areas or where the gas may produce a hazardous condition. Such an area could be a battery room in buildings or public exchanges or in underground mining applications, or under the bonnet of the average motor car where a faulty charging system may be detected.

The different applications of the present invention will require the unit to be housed appropriately.

Embodiments of the invention, which may be preferred, will be described in detail hereinafter with reference to the accompanying drawings, in which:-

Fig 1 is a block diagram of a basic energy monitor unit;

Fig 2 is a block diagram of a second - power back-up -embodiment of the energy monitor unit;

Fig 3 is a block diagram of the stationary embodiment of the energy monitor unit; and

Fig 4 is a block diagram of a vehicular embodiment of the energy monitor unit.

Dealing firstly with the basic energy monitor unit of Fig. 1, the Figure shows the unit located between storage cells (batteries) and an operating system which operates from the cells. The system may be a vehicle.

The components of the energy monitor unit are as listed hereunder, although the particular mix of components would depend on situation and/or customer requirements:-

1. Electronic current transducer using magnetic principle

2. D.C. breaker with manual override

3. Battery temperature sensor external

4. Battery temperature sensor internal

5. Hydrogen gas sensor

6. Energy level circuit and indicator

7. Battery energy monitor circuit 8. Voltage and current monitoring circuit

9. Current monitoring circuit

10. Battery preset information

11. Electronic load stabilizer

12. Housing

13. Radio transceiver

14. Remote radio transceiver

15. AC contactor for larger currents

16. A set of software tools to assist in Battery Application and design of backup systems.

The arrangement of Fig. 2 indicates the configuration that the unit may have in domestic, commercial or industrial applications. The monitoring unit will enable a greater degree of safety whenever batteries are used, at the same time providing a degree of protection for the batteries.

As discussed earlier in this specification the monitoring unit of this invention has been conceptualized to provide a unit that is able to monitor and provide a basic set of alarms and corrective actions when batteries are used. Importantly the unit checks that the battery set is not mis-used.

The block diagram of Fig. 3 shows the energy monitor unit in the stationary application form. This form has a few subtle differences when compared to the mobile adaptation of Fig. 4. The principle reason for that is that in the vehicular situation the unit is not or should not be allowed to isolate the alternator, from the battery, otherwise the alternator will be damaged.

To assist in controlling smaller variations of charging voltages, the use of an electronically adjustable load is crucial. This load, will provide a pulse width modulated current draw, to provide a controlled average value of current. The load can either be used in a series connection or in a parallel mode depending on whether the unit is a stationary, or mobile application, respectively.

Fig. 3 shows the stationary application of the unit with a full set of options. The main DC isolating unit is one that uses a high capacity contact system designed to break large DC currents, it is set by the application of a current, reset by either a mechanical lever or automatically. In ceratin circumstances it may be replaced with a commercial AC operated contactor or relay unit, with suitable rated contacts. In this instance the main processing unit will use the DC voltage to generate an AC voltage source, sufficient to operate the coil of the contactor. This allows the unit to use an industry standard AC contactor that has suitable ratings for DC operation. It also isolates any inductive spikes that are generated when operating coils.

The main processing unit may be implemented in either analog or discrete logic modes or using microprocessor technology that may also

incorporate an onboard analog to digital converter. The main functions of the processing system are:

1.0 Battery voltage sensing

2.0 Battery temperature sensing

3.0 Battery current sensing

3.1 Positive current is charge current

3.2 Negative current is discharge current 4.0 Input parameter evaluation

5.0 Rectifier current sensing

6.0 Hydrogen gas sensing

7.0 Battery energy calculation

8.0 Charge voltage compensation

9.0 Maximum current check

10.0 Energy level cut out calculations

11.0 Stabilizing load calculation and control

12.0 Contactor voltage supply, AC or DC

13.0 Energy level indication

14.0 Alarm status evaluation

15.0 External load calculation and control

The unit continually monitors the current to the battery and the temperature around the battery. If the rectifier does not have an input to provide voltage compensation, the unit will respond by:

1. In stationary applications, the electronic load will adjust the resistance path to the battery, excluding the path to the load, so that only the battery charge current is controlled.

2. In mobile application, the electronic load will provide an additional load across the battery to reduce the charge voltage. The unit will also have the option to exclude this feature or provide access to the headlights to assist in reducing the system load voltage by converting the extra energy to light.

An alarm indication is preferably given in the form of an LED display. If the unit senses the maximum charge current to the battery, then the electronic load will be applied to reduce the charging current. Should the stationary application will also isolate the battery for a calculated time.

This allows the battery to recompense for the gases produced before allowing the charge current to be re-applied. This action reduces dramatically the amount of gases produced, extends the life of the battery plates and reduces the internal pressure of the battery under charging conditions.

In mobile applications, the battery cannot be disconnected, so the electronic load is used to divert some of the current. This comprise is necessary to avoid damage to the alternator system. The unit preferably also incorporates transient suppression devices, as the alternator can generate excessive voltage spikes for short durations. The suppression will give added protection to any accessory equipment connected to the power system, or with the EFI (electronic fuel injection) systems, it will add an extra element of protection.

The alarm processing may also include a radio security link. The unit may be programmed to follow a power-on sequence, under adverse conditions, or if the vehicle wiring is tampered with the unit will send an alert signal to the receiver and inhibit the power source of the car. The unit in this configuration will preferably have an internal backup battery with which to power the radio link. The unit can also incorporate a vehicle alarm system with the battery energy monitor. This gives an integrated unit.

Elements of the unit will be described in detail under the following paragraphs 1.0 to 15.0. 1.0 Battery Voltage Sensing

The circuit will sense the current voltage of the cell. The unit will compare the voltage that has been programmed with that which is measured. Action is taken to ensure that the voltage remains in tolerance. This is done by using the electronic load. If the correction does not bring the voltage back, then an alarm is activated. The unit also translates the temperature of the cells, calculates the voltage necessary and corrects to this new value. Should the voltage applied to the battery set be outside the maximum level calculated, the battery set will be isolated in stationary application, or sets the electronic load to maximum, at the same time alerting the operators to the misuse. 2.0 Battery Temperature Sensing

The circuit measures the temperature of the application environment and produces a correction value to maintain the correct voltage. The sensor may be either internal or an optional external sensor that may be placed strategically near the battery. 3.0 Battery Current Sensing

The level of current flowing into and out of the battery is continually monitored. Action is taken to make sure that the charge current is within the maximum limit and with the battery voltage is used to calculate the energy level drawn from or passed to the battery. This energy level is also used to provide a measure to check when the battery is to be isolated

whenever the main power source us lost. The preset value will be calculated from the normal current use.

For mobile sets, the nominal current for starting is used to determine the cutoff energy that will give a reserve of a minimum number of attempts, when the cut-out has been activated for the first time. 4.0 Input Parameter Evaluation

The switch settings for the unit will provide the necessary default values for the operation of the unit. The parameters are:

Nominal voltage for battery

Maximum charge current

Ampere-hour value of battery

Maximum discharge current for battery

Sealed or wet battery types

Temperature compensation, volts per degree Kelvin

Lead acid or nickel cadmium battery type

Maximum current from the rectifier

Maximum load current

Internal or external temperature sensing

Internal or external electronic load

AC or DC supply for the isolators

Hydrogen gas sensor 5.0 Rectifier Current Sensing

The maximum current for the unit is set into the system. If the rectifier current exceeds this value, or if the combined battery and rectifier currents are in excess of the maximum load current, the unit will isolate the load. This action will reduce the likelihood of damaging currents from flowing, set the overload status and protect the equipment and operators from excessive harm. 6.0 Hydrogen Gas Sensing

This unit is optional and would be used to detect the presence of hydrogen gas from the batteries. The unit will isolate or reduce the charging current and an alarm set to indicate the presence of a potentially explosive gas mix. The unit may operate strategically placed fans to dilute the gas mix. Under larger concentration, the unit will isolate the rectifiers and set the alarm. 8.0 Charge Voltage Compensation

The value is set from the input switch settings. The correction voltage is either sent to the rectifier or to the electronic load in an attempt to bring the voltage into line. Should the corrective action be

outside the circuits ability to correct, the alarm is set to indicate an over or under charging condition. 9.0 Maximum Current Check

The maximum currents that can occur are continually monitored and sent to the electronic load or the isolator. The action will be determined according to values and the direction of the current flow. There is a maximum fault current for the batteries, which is used as a basis for isolating the battery and rectifier from the load. 10.0 Energy Level Cut Out Calculation

Information from the current sensors and the voltage sensor, is used to determine the level of energy that must remain in the battery after the first cut out condition. This level is determined by sensing and recording of the normal current and voltage, and setting an appropriate level to allow the unit to hold 40% of the energy. This value will be a function of the application and programmed into the unit's main memory. 11.0 Stabilizing Load Control

The electronic load is used to bring the battery condition into line. The load has either internal or external dissipation. It will be a pulse width modulated action providing an average action. It will also provide a feedback to allow determination on the effectiveness of the control. If the unit cannot bring the condition into line, then the load will be set to maximum and action taken to minimize the offending condition. 12.0 Contactor or Isolator Voltage

The unit will provide an isolated AC supply, as an option or in stationary applications, to allow AC operated contactors of 24v AC rating coils to be used. This is switch selected. 13.0 Energy Level Indication

Information from the energy cut out is used on a continuous basis to display the energy level of the battery. This is only an indication. It is stated by certain manufacturers that batteries need to be cycled in float conditions in order to develop the capacity of the battery. The majority of the batteries do not have 100% capacity when manufactured, due in part to the chemistry of the cell. 14.0 Alarm Status Indication

This unit will interpret the individual alarm conditions and present the information in LED form. It also has the option of a radio link to allow information to be transferred to the operator in remote or high security applications. The radio link provides a two way link so that certain control may be had remotely. 15.0 External Load Calculation and Control

The external unit is switch selected. The amount of dissipated current is measured so that the effect of the electronic load can be calculated.

The mobile application arrangement of Fig. 4 has some differences from that of Fig. 3.

The main differences are in the functional blocks "Alternator stabilizing load" and "Suppression and smoothing circuit". The other difference is in the wiring between the blocks, as the alternator cannot be disconnected directly from the battery. Isolation in this case is achieved by cutting off the main isolator. This will cut out the voltage supply to the regulator, which will stop the alternator output.

The residual energy level will in this case be the supply of a current for a predetermined time. The alarm status and radio link will function as per the stationary application.

The operation of the unit is principally active during the starting phase of the vehicle. During normal running the unit will be acting as a charging system monitor. In this mode, alarm status is given when any faults occur, with the electronic load being used in an attempt to correct over-charging conditions. Isolation will only occur during start up phase, not, generally speaking, during the running phase.

Claims

CLAIMS:

1. An energy monitor unit for a storage cell, said unit being adapted to monitor parameters associated with said cell and being adapted to initiate certain action as a result of charges in said parameters.

2. A unit according to claim 1, wherein the parameters include load environment, discharge current, and charging current, and one action said unit is adapted to take is to cut off energy discharge to leave safe residual energy in said cell for emergency applications.

3. A unit according to claim 2, wherein said environment parameter is ambient temperature and said load parameter is cell voltage.

4. A unit according to claim 2 or claim 3, further including a second cut off facility so that when emergency energy is discharged, deep discharge is prevented.

5. A unit according to any preceding claim, further including radio transmission facilities to enable remote communication of cell status and alarm information.

6. A unit according to any preceding claim, further including a hydrogen and/or oxygen gas sensor.

7. A unit according to any preceding claim wherein the unit is adapted for stationary applications.

8. A unit according to any one of claims 1 to 6, wherein the unit is adapted for vehicular applications.