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).
The development of a dynamo and half-charge resistance scheme for the vehicle's electrical system.
| Identifier | ExFiles\Box 163\6\ img081 | |
| Date | 1st December 1930 | |
| EFCl/ADL.12.30. contd. -2- in developing a machine capable of "high" output in order to balance the heavy head lamp currents for night running at high speeds, some loss of cutting in was inevitable in our present size and weight of dynamo. For Town running with the half charge scheme, it was concluded that the half charge resistance could be no greater than the 6" and even then there might be some doubt as to whether the charge of the system would be maintained. It was arranged, however, that the car 58-GN would continue to run with this resistance starting with the battery in a reasonably well charged condition to find out whether the system would maintain itself. This will be valuable evidence to us here of a kind that we practically cannot get on the experimental cars at Derby. Further, it was agreed that there would have to be more than one value of resistance for different circumstances of running but it was not thought that any one owner should be provided with more then one such resistance. In view of the existence of some doubt in the matter of maintenance of the system in town running, it was suggested that R.{Sir Henry Royce} might be approached as to the possibility of increasing the length of the dynamo by say 1/2" or 3/4" as, it will be remembered, was done at our suggestion in the case of the starter motor to enable us to get suitable characteristics. It may not, however, be such a good proposition in the case of the dynamo in view of the continuous running of this unit. We have, from time to time, suggested that a larger machine is needed. To increase the diameter, probably, is impracticable both as regards present design and as regards the high speed at which the dynamo armature has to run. PN.{Mr Northey} himself is inclined to the feeling that for town running circumstances the half charge scheme is not necessary i.e. that full charge should always be available. He, however, agrees as to the suitability of this in the other extreme cases. From the point of view of standardisation therefore, it would appear that this half charge scheme is still the best we can do at the moment subject to supplying different values of the resistance (one resistance only per car) to suit different average circumstances of running. | ||