From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Continued discussion on vehicle electrical system requirements, focusing on battery charging and dynamo performance.
| Identifier | ExFiles\Box 31\1\ Scan135 | |
| Date | 3rd November 1922 | |
| Contd. -3- EFCL/T3.11.22. If the battery alone is on circuit, this means that the charging current increases as the battery reaches the end of its charge - a very undesirable condition. The true requirements of the average chassis system are to some extent met by using a dynamo of the type with single field winding and third brush control, because with this arrangement a larger output is produced at moderate speeds than at high speeds, and there is less danger of the battery being excessively overcharged at touring speeds in daylight. The ampere output speed curve should drop away from the maximum to such an extent as to effect at high speeds a satisfactory compromise between daylight conditions and those at night as regards charging and discharging of the battery, and it should not in our opinion be objected to if, under night conditions at high speed, the battery is asked to discharge a small current to assist the dynamo in the lighting. At more moderate speeds the dynamo output would balance the lamp load. What is required, however, is some system which will not merely satisfactorily meet the variations in the average owner's use of the car, but also the extreme variations in the cases of different owners, and in our opinion no system based on the so-called 'inherently controlled' generator can do this. An ordinary shunt wound dynamo whose output is controlled by the application of some form of external Contd. | ||