| 摘要 |
<p>A typical motor vehicle has an electrical storage battery (BT) to power its electrical facilities (L), including facilities which normally consume current when the vehicle is left unattended. A control system (CU) for the electrical supply system comprises means for generating a first relatively low reference voltage (VR1) and a second relatively high reference voltage (VR2), each selected to conform to a pre-selected battery condition; a first timing means (T1) operable for a relatively short period and a second timing means (T2) operable for a relatively long period. The timers operate from the time when the driver leaves the vehicle. A first voltage comparator (C1) is arranged to compare the actual battery voltage with the first reference voltage after said relatively short period and thereafter to provide a low battery signal if the actual voltage is below the first reference voltage. Similarly a second voltage comparator (C2) is arranged to compare actual battery voltage with the second reference voltage after said relatively long period and thereafter to provide a low battery signal if the actual voltage is below the first reference voltage. The battery is isolated from the electrical system (at master switch MS) in response to either low battery signal to preserve some battery charge and is reconnected by the driver on return to the vehicle, for example in response operation of an ignition switch (IS).</p> |
