# US 4,396,889 A · Nonadjusting battery life detector

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 4,396,889 A
- Document ID: US4396889A
- Status: Granted
- Kind: A
- Application number: 06/213,619
- Filed: 1980-12-05
- Granted: 1983-08-02
- Earliest claimed: 1979-12-22
- Assignees: Kabushiki Kaisha Daini Seikosha
- Inventors: Satoshi Arai
- Web page: https://patentgrep.com/patent/US4396889A

## CPC

- G01R 19/16542: {for batteries (charge condition monitoring in G01R31/36)}
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)

## Abstract

A battery life detector operates by sensing battery voltage. The detector consists of a pair of series combinations of a constant voltage source and a constant current source which are connected to a terminal to which a battery voltage is applied. The constant voltage source outputs are connected to respective inputs of a differential amplifier.

## Claims

### Claim 1

Nonadjusting battery life detector characterized in that a first constant voltage source for generating a constant voltage relative to the ground is connected to a battery in series through a first constant current source, a second constant voltage source for generating a constant voltage is connected to the battery in series through a second constant current source, and the constant output voltages from the first and second constant voltage sources are supplied to the two input terminals of a differential amplifier, respectively.

### Claim 2 (depends on 1)

Nonadjusting battery life detector as claimed in claim 1 characterized in that a first sampling transistor is connected between the second constant current source and the ground, a second sampling transistor is connected between the first constant current source and the battery, and a collector of the second sampling transistor is connected to the battery terminal of the differential amplifier.

### Claim 3

A battery life detector, comprising:
a differential amplifier having a non-inverting input and an inverting input;
a terminal for connection, in use, to a battery for receiving a battery voltage to be detected;
a first constant voltage source having an output terminal connected to the non-inverting input of said differential amplifier for applying a constant voltage to the differential amplifier non-inverting input;
a first constant current source connected in series with said first constant voltage source for applying a constant current to said first constant voltage source;
a second constant voltage source having an output terminal connected to the inverting input of said differential amplifier for applying a constant voltage to the differential amplifier inverting input;
a second constant current source connected in series with said second constant voltage source for applying a constant current to said second constant voltage source; and
means for intermittently connecting the series combination of said first constant voltage source and said first constant current source to said terminal and for intermittently connecting the series combination of said second constant voltage source and said second constant current source to said terminal thereby to operate the battery detector circuit in a sampling operating mode.

### Claim 4 (depends on 3)

A battery life detector according to claim 3, wherein said means for intermittently connecting is comprised of a first transistor having a collector-emitter path connected in series with said second constant current source and ground, and a second transistor having two collectors with a first collector-emitter path connected in series with said first constant current source and said terminal and with a second collector-emitter path connected in series with a power input of said differential amplifier and said terminal.