Electricity: battery or capacitor charging or discharging – Serially connected batteries or cells – With discharge of cells or batteries
Patent
1991-01-29
1992-08-18
Stephan, Steven L.
Electricity: battery or capacitor charging or discharging
Serially connected batteries or cells
With discharge of cells or batteries
320 2, 307 107, H02H 718, H02J 704
Patent
active
051402505
DESCRIPTION:
BRIEF SUMMARY
The present invention relates to the protection of a battery-powered engine ignition system against inadvertent discharge of the battery.
The invention is applicable particularly but not exclusively to the engine ignition systems of cars and other motor vehicles. It is not uncommon for a car driver to inadvertently leave the vehicle lights switched on when he parks the car, with the result the car battery is completely discharged when he returns, so that the engine ignition system cannot be used to start the engine. Similar problems can arise in other modes of transport which rely on a battery-powered engine ignition system.
An object of the present invention is to overcome or alleviate such problems.
Accordingly, the invention provides a protective circuit for a battery-powdered engine ignition system, said circuit including first and second terminals for connection in series with a discharge circuit of the battery, and normally ON switching means connected between said terminals, said circuit being arranged to switch said switching means OFF in response to an input signal indicative of partial battery discharge and the switching means being resettable by a user from OFF to ON to enable the engine ignition system to the activated by the battery when it is partially discharged.
The invention also includes within its scope a battery-powered engine ignition system incorporating such a protective circuit with its first and second terminals connected in series with a discharge circuit of the battery.
Such a protective circuit or engine ignition system may be incorporated in any vehicle, boat, aircraft or hovercraft which relies on electric power for starting its engine and accordingly it will be noted that the application of the invention is not restricted to motor vehicles.
Particularly in cases where the battery voltage declines significantly during discharge, the protective circuit is suitably responsive to an input signal in the form of a sensed battery voltage which is below a predetermined level. However, it is envisaged that other means for detecting discharge of the battery may be employed to generate the required input signal; for example, a sensor may be arranged to detect the discharge current of the battery when the engine is switched off and to generate said input signal when the discharge current exceeds a predetermined value for a predetermined time, or a function of discharge current and time reaches a predetermined value which is indicative of significant battery discharge.
Preferably the switching means is resettable by the user from OFF to ON by means of a further input signal which temporarily varies a voltage level within the circuit. This provides sufficient time for the user to energise the ignition system (e.g. by turning the ignition key in the case of a motor vehicle) so that the engine starts. Preferably a control signal is generated, for example, from the voltage on the ignition coil, which overrides said input signal and maintains the switching means ON whilst the ignition system is energised. However, in some cases the battery voltage may rise sufficiently in response to charging of the battery that the switching means remains reset in the ON condition and the above-mentioned control signal is unnecessary.
In accordance with a further preferred feature of the invention, the protective circuit is so arranged that the switching means can be set to the OFF state by a further input signal from the user so as to prevent the ignition being activated until the switching means is reset by the user. This is a useful theft-prevention measure since it prevents an authorised activation of the ignition system. For example, a motor vehicle may be provided with an infrared or ultrasonic receiver on its exterior which is arranged to reset the switching means to the ON state in response to a predetermined infrared or ultrasonic signal generated by a hand-held transmitter operated by the user of the vehicle on returning to the vehicle. Before leaving the vehicle, the user may deactivate the ignitio
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Davidson Ben
Motronix Limited
Stephan Steven L.
LandOfFree
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