JP2731850B2 - How to judge the life of an automotive storage battery - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for judging the life of a storage battery for an automobile, and an object of the present invention is to improve the prediction accuracy of life deterioration.

2. Description of the Related Art Conventional technology and its problems Since a storage battery for an automobile is mainly used for starting an engine, in order to prevent troubles such as an inability to start the engine and engine stalling during traveling, a reduction in the capacity of the storage battery and a deterioration in the life of the storage battery have been required. Various battery condition monitors have been devised for detection purposes.

However, usually, a storage battery for an automobile is configured by integrating six 2V cells in series, and furthermore, its capacity reduction and life deterioration modes are various, and the capacity reduction and life deterioration are quantitatively and accurately determined. It is difficult to do so, and only a rough estimation of the capacity of the storage battery is made based on changes in the storage battery voltage during charging and discharging. In particular, it is difficult to detect the life deterioration in advance, and it is almost impossible to distinguish it from a mere reduction in capacity due to charge / discharge imbalance.

Means for Solving the Problems The present invention has been made for the purpose of solving such a conventional problem, and focuses on the correlation between the terminal voltages of the storage battery before the engine is started and during the start. A mechanism for detecting the terminal voltage of the storage battery and the terminal voltage of the storage battery during engine start, and storing the detection result by the detection mechanism, and storing the terminal voltage of the storage battery before engine start and the terminal of the storage battery during engine start based on the stored contents. A mechanism that approximates the relationship with the voltage as a linear relationship, and increases the alternator charging voltage if the linear relationship obtained by the approximate calculation means, including the detection result at any time, is less than a predetermined reference value. If the number of times the value is less than the reference value is continuously generated for a predetermined number of times or more, the warning display means displays a battery life deterioration warning. A mechanism for detecting the engine block temperature and the outside air temperature has been added. Regarding the detection results of the terminal voltage of the storage battery before and during the start of the engine, the temperature of the outside air temperature and the temperature of the engine block are kept below a certain temperature. The detection result is adopted only when the difference is equal to or less than a predetermined value.

According to the configuration of the present invention as described above, the charge / discharge amp of the state of the storage battery is determined from the terminal voltage of the storage battery before the engine is started and the terminal voltage of the storage battery during the engine start, while considering the history of the storage battery when the engine is started. It is difficult to restart the engine if the charge voltage is increased or the capacity is reduced due to the deterioration of the service life. The warning is given in advance of the possibility that the engine will stall during driving.

FIG. 1 is a circuit block diagram showing an embodiment of the present invention. First, the configuration will be described. A storage battery 1 drives the starter 2 when the engine is started, and is connected in parallel with a load to the alternator 3 after the engine is started, and is charged by the alternator 3.

Reference numeral 4 denotes a shunt resistor for current detection at the time of engine start inserted in series with the storage battery, and its voltage output is input to a voltage / temperature detection circuit 5, and measurement of the electronic voltage Vc of the storage battery during engine start is a predetermined current. It is always done at a value, for example 150A. Reference numeral 14 denotes a temperature measuring element set on the engine block and the vehicle body.

Battery terminal voltage Vb before engine start, battery terminal voltage Vc during engine start, and engine block temperature T
a, the outside air temperature Tc is monitored by the voltage / temperature detection circuit 5 and is input to the storage battery state determination circuit 7 via the A / D conversion circuit 6.

The state determination circuit 7 of the storage battery is constituted by arithmetic means by a microcomputer. Vb and Vc converted into digital signals by the A / D conversion circuit are input to the microcomputer 8. The microcomputer 8 is provided with a CPU 9 as arithmetic means, a RAM 10 for temporarily storing input data, and a ROM 11 for fixedly storing a processing program for forewarning and deteriorating the life of the storage battery. State determination circuit 7 together with the drive circuit 12
Is composed.

Next, the operation of the state determination circuit 7 mainly composed of the CPU 9 will be specifically described with reference to the flowchart of FIG.

The CPU constantly monitors the start of the engine, and reads the terminal voltage Vb of the storage battery, the engine block temperature Ta, and the outside air temperature Tc before the engine is started in step 15 based on the key switch ON signal. Subsequently, the current during startup is monitored by the output voltage of the shunt resistor 4, and the terminal voltage Vc of the storage battery is read within a predetermined current value, for example, 0.2 seconds 0.1 seconds within a predetermined time range of 150 A, for example. Read voltage Vb, V
c is the storage battery voltage Vb, V only when the engine block temperature Ta is equal to or lower than the predetermined temperature Tb and the temperature difference between the outside air temperature and the engine block temperature is equal to or lower than the predetermined temperature Td.
It is determined that the influence of the previous traveling history is small in c, and the operation of the CPU stores the state data of the storage battery in the RAM 10 in step 16. The correlation between the battery voltage before starting the engine and the battery voltage during starting of the engine is unstable immediately after the vehicle stops, and accurate correlation data must be stored in a state where there is no history of vehicle travel in the storage battery. It is desirable to collect. As an indicator that the influence of the history is decreasing, it is effective to confirm the decrease in the engine block temperature and to confirm the temperature difference between the outside air temperature and the engine block temperature, and the data reliability can be improved. The state data of the storage battery is accumulated up to ten times in the past, and when the latest data of Vb and Vc is read, general old data is deleted.

Subsequently, the CPU performs an approximate calculation on the basis of the accumulated data including the latest data in step 17 on the basis of the data of 10 times, assuming that Vb and Vc are linear relationships, and obtains the relationship of Vc = A × Vb + C. , A, C are stored in the RAM 10.

The CPU performs the above-described linear approximation calculation based on the accumulated data including the latest data every time the engine is started and the data of Vb and Vc are updated.
Update the values of A and C.

In the storage battery, the values of Vb and Vc decrease as the capacity decreases.
FIG. 3 shows this relationship, and there is a linear relationship between Vb and Vc.

However, when the capacity of the storage battery is reduced due to deterioration of the service life, a thread occurs in the correlation between Vb and Vc, and Vb
Is high, the value of Vc is not so high. This relationship is shown in the straight-line graph of the new product and the product whose life has deteriorated in FIG. This means that in the above relational expressions, the coefficients A and C decrease and the Vc decreases, and the degree of deviation of the values of A and C from the reference value and the degree of decrease of the Vc are used to evaluate the life deterioration degree of the storage battery. be able to.

In steps 18 to 20, the CPU stores the updated values A, C, and Vc in ROM 9
, For example, A ₀ = 1, C ₀ = −3.5 V, Vc ₀
If the updated values are less than these values compared to 9.8 V, the charging voltage is increased in step 22 to recover the capacity of the storage battery. After running for a certain period of time in this state, the CPU repeats the state determination from step 15 again at the next engine start. In step 21, the number of times less than the reference value of A, C, and Vc is counted. Activate the storage battery life deterioration warning display device 13
Displays a warning of life deterioration.

Effect of the Invention As described above, according to the present invention, the state of life degradation of a storage battery is determined from a change in terminal voltage of the storage battery at the time of engine start, and a highly reliable life degradation alarm is issued with a margin before traveling. As a result, troubles such as engine inability to start due to life deterioration and engine stall during running can be greatly reduced, and the reliability of the storage battery can be improved.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram showing an embodiment of the life determining method of the present invention, FIG. 2 is a calculation flowchart showing the operation of a state determining circuit, and FIG. 5 is a characteristic graph showing a relationship between the storage battery and the terminal voltage Vc. DESCRIPTION OF SYMBOLS 1 ... Storage battery 2 ... Starter 3 ... Alternator 4 ... Shunt resistance 5 ... Temperature detection circuit 6 ... A / D conversion circuit 7 ... State determination circuit 8 ... Microcomputer 9 ... CPU 10… RAM 11… ROM, 12… Drive circuit 13… Battery life degradation warning display 14 …… Engine block temperature and outside temperature

Claims (2)

(57) [Claims] 1. A mechanism for detecting a terminal voltage of a storage battery before and during engine start and a detection result stored by the detection mechanism. A mechanism for approximating the relationship is provided, and when the linear relationship obtained by the approximation calculating means including the detection result at an arbitrary time is less than a predetermined reference value, the charging voltage of the alternator is increased to satisfy the reference value. A method for determining the life of a storage battery for an automobile, wherein the warning display means displays a warning indicating that the life of the storage battery has deteriorated when the occurrence of the failure does not occur continuously more than a predetermined number of times. 2. A mechanism for detecting an engine block temperature and an outside air temperature is added, and the detection results of the terminal voltage of the storage battery before and during the engine start are set so that the engine block temperature is equal to or lower than a predetermined temperature and the outside air temperature and the engine block The method according to claim 1, wherein the detection result is adopted only when the temperature difference from the temperature is equal to or less than a predetermined value.
3. The method for judging the life of a storage battery for an automobile according to the above item.