JPS6081779A - Prevention of car battery overdischarge - Google Patents

Abstract

PURPOSE:To prevent the overdischarge of a car battery by cutting off at least a part of the battery load considering the result of: detecting the specific gravity and temperature of a battery electrolyte, converting these detected values by use of their functions, and comparing these converted values. CONSTITUTION:With the use of an electrolyte temperature sensor 3, an electrolyte surface sensor 4, an electrolyte specific gravity sensor 5, a surface compensation circuit 6 for the electrolyte specific gravity, an electrolyte specific gravity- discharge depth conversion circuit 7, and an electrolyte temperature-discharge depth conversion circuit 8, the discharge depth Q is obtained as a function of the electrolyte specific gravity, and the discharge depth set value Qs, which indicates the limit to be capable of maintaining the start performance, is gained as a function of the electrolyte temperature; and these two values are compared by a comparison circuit 9. When Q>alphaQs, the load unnecessary for safe driving is cut off by a magnet switch 2, where alpha is a safety margin for which 0.6-0.8 is appropriate. In this way, such a kind of trouble that a car battery may be overdischarged, leading to a failure to restart an engine, can be avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing overdischarge of an automobile battery.

To keep the batteries used in cars in good condition,
A proper balance between discharge amount and charge amount is essential. Under normal usage conditions, the charge/discharge balance is maintained sufficiently, but if additional equipment or accessories such as the cooler, stay A, and poppy device are added, the charge/discharge balance may be maintained at night or in the rain. Under driving conditions where the electrical load required by the machine is large, or under conditions where the battery is charged, such as when driving at low speeds or short distances, the amount of charge may be insufficient compared to the amount of discharge, and the state of discharge may become deeper and deeper during driving. It's becoming. Finally, the required performance of the battery exceeds the limit that can be maintained, and it becomes impossible to move the baby again after stopping.

In order to prevent the above-mentioned troubles, the present invention detects the depth of discharge (Q) of the battery and sets it to the set ta (Qs).
9. A method for preventing overdischarge of an automobile battery, which cuts off electrical loads that are not necessary for the safe operation of a vehicle to stop the discharge from deepening, or reduces the speed at which the discharge deepens.
That is, the electrolyte specific gravity d5 and electrolyte temperature of batteries used in automobiles are detected, each detected value is converted using a function, these converted values are compared, and the battery load is adjusted according to the comparison value. Provided is a method for preventing overdischarge of an automobile battery, which prevents overdischarge of the battery by blocking at least a portion of the battery.
It is something that This will be explained in detail below.

For detecting the depth of discharge of a battery, it is appropriate to use the electrolyte specific gravity, which decreases in proportion to the amount of discharge. Specific gravity when fully charged is 1
．． 280, for a battery with specific gravity i, ioo at full discharge, if the detected electrolyte specific gravity value is Sp, the detected depth of discharge is (1>
It is shown by the formula.

Detection depth of discharge Q-bu (Sp) = detection electrolyte specific gravity decrease/total discharge electrolyte specific gravity decrease - (1,28 (1-8t))/
< 1,280-1.100)... Equation (1) On the other hand, the set value (QS) corresponds to the limit depth of discharge at which starting performance can be maintained, and it changes depending on the temperature of the battery or electrolyte. . Figure 1 shows an example of the experimental results of the relationship between the electrolyte temperature and the maximum depth of discharge that can maintain starting performance. As is clear from Fig. 1, the set value (QS)
is a function of temperature t.

QS = f<t>...Equation (2) Therefore, the discharge depth Q, which is a function of electrolyte specific gravity in equation (1), is compared with the set value Qs, which is a function of humidity in equation 2). ,
Loads unnecessary for safe driving may be cut off under the following conditions. Here, α is the safety factor, and 0.6 to 0.8 is appropriate. In the above, the electrolyte temperature did not affect the electrolyte specific gravity, so the effect was ignored, but in practice it is necessary to correct it. The detected electrolyte specific gravity value SO in equation (1) is generally a value at 20°C. And the detection electrolyte specific gravity 3t which is a3 at the electrolyte temperature 1 is practically <3
The discharge depth Q is a function of both the detected electrolyte specific gravity value 3j and the electrolyte temperature t.

S p= S L -1-0,0007(1-2(1)
...Formula (3) Furthermore, since the specific gravity of the electrolyte changes depending on the height of the electrolyte, it is necessary to correct it. Under usage conditions where over-discharge is a concern, the liquid level does not decrease drastically, and with proper maintenance, the specific gravity level can be compensated.
Although F is unnecessary, the case where correction is made is as follows.

The liquid level corrected electrolyte specific gravity value Spa is calculated by equation (4).

5IlO = 20℃ (specific gravity measurement value + compensation coefficient x detection liquid level height -8p → -KX (let-kt) (ht:
Detected liquid level height, k: temperature coefficient)...Kawa (4) formula If this liquid level corrected electrolyte specific gravity value spo is used in place of the detected electrolyte specific gravity 1ifl S p in formula (1), the discharge depth Q Gamaru. Since the positive value spo of the liquid level corrected electrolyte + is a linear function of the detected electrolyte specific gravity value st, the detected liquid level height 1+t, and the detected electrolyte temperature t, it is the depth of discharge. The comparison of the setting fK1Qs results in a comparison of the functions of the detected electrolyte specific gravity, the detected liquid level height, and the electrolyte temperature.

For J3 above, the specific gravity of the electrolyte, the height of the electrolyte level,
We have described a method of controlling the depth of discharge by detecting the electrolyte temperature and determining the depth of discharge of the battery, and cutting off the excess load accordingly.In order to further improve the effect of this method, it is necessary to set the depth of discharge. It is desirable to issue a warning to the driver at the same time when the excess load is cut off when the value exceeds the limit, and to urge caution to drive in a manner that is likely to lead to overcharging.

Based on the method described above, the electrolyte specific gravity, electrolyte M liquid level height J
Figure 2 shows a type 1 circuit configuration of a device that detects the electrolyte temperature and electrolyte temperature, cuts off excess load, and issues an alarm. In Figure 2, δ3 is shown, 1 is the battery, 2 is the magnet 1~
3 is an electrolyte preparation lens, 1 is an electrolyte liquid level lens, 55 is an electrolyte specific gravity sensor 4 NO, 6 is a liquid level correction circuit for electrolyte specific gravity, 7 is an electrolyte specific gravity-discharge depth conversion circuit, 8 is An electrolyte depletion/depletion depth conversion circuit, 9 a comparison circuit, 10 a magnet switch drive circuit, and 11 an alarm lamp are connected as shown in the figure. All the circuits are made using publicly known circuits.

As described above, according to the present invention, it is possible to prevent over-discharging of an automobile battery by cutting off electrical loads that are not necessary for safe driving in an automatic vehicle, and therefore it is possible to over-discharge the battery and restart the vehicle. This will help prevent problems such as not being able to do it.

[Brief explanation of drawings]

Figure 1 is a characteristic diagram showing an example of the relationship between the electrolyte temperature applied to an automobile battery and the maximum depth of discharge that can maintain starting performance, and Figure 2 is a method for preventing overdischarge of an automobile battery according to the present invention. This is a circuit diagram showing an example of a device using the following. 150 1. Indication of the matter A'1 Show 1
Title of Invention Law for Preventing Over-Discharge of Automotive Batteries Representative Mori 01 Masatoshi's [Detailed Description of the Invention] column of the specification. 6. Contents of amendment (1) rsp10t< on page 5, line 5 to line 6 of the specification
X (ht - kt) (1 + t: detected oil level height, 1 curse:) B degree coefficient)
+) (h: Detected oil level height, g: Temperature system number, t: Detected fff melted liquid temperature) Corrected to 1. (2) “Detected oil level height 111” on page 5, line 10 of the specification
Correct ``detected oil level height 11'' by 31. 1 sou 1

Claims (1)

[Claims] 1) Detecting the electrolyte specific gravity and electrolyte temperature of an rFX cell used in an automobile, converting each detected value using a function, comparing the converted values, and comparing the detected values. A method for preventing over-discharge of an automobile battery, which prevents over-discharge of a battery by cutting off at least a portion of a battery load in accordance with the above. 2> The method for preventing overdischarge of an automobile battery according to claim 1, wherein the detected value of the electrolyte specific gravity is corrected according to the electrolyte level height. 3) A method for preventing overdischarge of an automobile battery according to claim 1) or 2), wherein an overdischarge alarm is issued in conjunction with load cutoff.