JPH0367180A - Battery-down detecting method - Google Patents

Abstract

PURPOSE:To let the user of a system know the proper replacement period of a battery by sampling the voltage of the battery at constant intervals of time and finding the voltage-loss characteristics of the battery according to the result. CONSTITUTION:An H/W2 for battery voltage measurement is arranged in the circuit of the battery which backs up a nonvolatile memory 3. Then the H/W2 is accessed at constant intervals of time to sample the voltage value of the battery 1. The voltage-loss characteristic is found by using a specific expression according to the result to predict a voltage value after the period of the measurement and the time when the voltage becomes lower than the limit value of a backup voltage is judged to inform the user of the system of the proper replacement period of the battery.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a battery-down detection method for detecting a voltage drop in a battery that banks up a non-volatile memory that stores system information and the like.

[Conventional technology]

In the conventional battery-down detection method, it is detected that the battery voltage has fallen below a certain value VA (backup voltage limit value VB+margin), and the system user is notified of this detection result.

[Problem to be solved by the invention]

However, in the conventional puff battery down detection method described above, the time required for the battery voltage to change from VA to VB is not uniform due to variations in battery loss characteristics due to the characteristics of the battery, backup memory, etc. There was a problem in which the timing of battery replacement was unclear. [Means for solving the problem] The present invention was made to solve this problem. The voltage loss characteristics of the battery are predicted based on the sampling results, and the appropriate time to replace the battery is notified based on the predicted voltage loss characteristics.

[Effect]

Therefore, according to the present invention, the user of the system is notified of the appropriate time to replace the buff battery based on the predicted voltage loss characteristics.

〔Example〕

Hereinafter, the puff tissue down detection method according to the present invention will be explained in detail.

FIG. 2 is a circuit configuration diagram to which this battery-down detection method is applied, in which 1 is a battery, 2 is a battery voltage measurement H/W, and 3 is a nonvolatile memory.

In such a configuration, the battery voltage measurement H/W2
By accessing , you can sample the voltage value of battery 1, and by doing this at regular intervals,
Voltage loss characteristics as shown in FIG. 3 can be obtained.

In addition, in FIG. 3, vO is the initial voltage value of the battery 1, and VB is the limit value of the bank-up voltage.

FIG. 1 shows an enlarged view of the line AA' in FIG. 3. Observation time 1. The voltage difference between and t2 is ΔV1, the same < tz
and t, the voltage difference between t, ΔV2, t, and t4, ΔV3, t4 and t.

Let the voltage difference between the two be Δ■4. Now, when the values of ΔV1 and Δv2 are sampled, Δv3 can be approximated by the following formula.

ΔV3=Δ■2+(Δ■2−ΔVl) =2*ΔV2−Δv1 Similarly, the voltage difference ΔvN between tN++ and 1N is Δ
VN=(N-1)*ΔV2-(N-2)*ΔV1...(1) It is expressed as follows. From equation (1), the voltage value VN at tN is V
N=V1-(ΔV1+Δ■2+ΔV3+ΔV4+ΔV5
+...ΔVN) =V1-Σ(ΔVi) =V1-N* (2*Δv1-ΔV2)-N* (N+
1) *(ΔV2−Δvl)/2·(2) It can be expressed as follows.

This allows the AI function to predict the voltage value after the observation time. Since the time T during which the VNO value falls below the limit value VB of the backup voltage can be determined by N* (sampling period), it becomes possible to notify the system user of a more appropriate time to replace the battery.

〔Effect of the invention〕

As explained above, according to the battery down detection method according to the present invention, the voltage of the battery is sampled at regular intervals, the voltage loss characteristics of the battery are predicted based on the sampling results, and the battery is properly adjusted based on the predicted voltage loss characteristics. Since the appropriate time to replace the battery is notified, the user of the system is notified of the appropriate time to replace the battery, and the time to replace the battery becomes clear.

[Brief explanation of drawings]

Figure 1 is an enlarged view between A-A' in Figure 3, Figure 2 is a circuit configuration diagram to which the battery-down detection method according to the present invention is applied, and Figure 3 is an access to the battery voltage measurement H/W. FIG. 2 is a diagram showing voltage loss characteristics of a battery obtained by 1... Battery, 2... H/W for measuring battery voltage
, 3...Nonvolatile memory. Figure 1 Figure 2 Figure 3

Claims (1)

[Claims] In a battery down detection method for detecting a voltage drop in a battery that backs up non-volatile memory, the voltage of the battery is sampled at regular intervals, the voltage loss characteristics of the battery are predicted based on the sampling results, and the predicted voltage loss is A dead battery detection method that notifies an appropriate time to replace the battery based on characteristics.