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).
Over-voltage issues causing side lamp bulb filaments to burn out on trials cars.
| Identifier | ExFiles\Box 166\4\ img133 | |
| Date | 2nd April 1932 | |
| JLE.{J. Lee Evans - Chassis Test Manager} from Hs{Lord Ernest Hives - Chair}/Wst. c. EP.{G. Eric Platford - Chief Quality Engineer} c. MX.{John H Maddocks - Chief Proving Officer} X6089 Hs{Lord Ernest Hives - Chair}/Wst.1/ADL 2.4.32. SIDE LAMP BULBS With reference to LEG/C/7.4.32 regarding the side lamp bulbs on trials cars giving trouble due to the filaments burning out, we would confirm that this is probably due to over-voltage. We have carried out some tests some time ago when we standardised the half charge system and we showed that with the dynamo charging at its peak output and the battery fully charged with the switch in the SMT position, it was possible to get a voltage of 16.5 in the case of the 20/25 chassis and 16.25 in the case of the 40/50 chassis at the side lamp bulb terminals. These voltages were obtained with 4 watt side lamp and tail lamp bulbs. In the case of the standard recommended 6 watt bulbs, obviously the voltage will be lower. Since it is only in Town work that these lamps are likely to be used alone and under conditions of frequent stopping and starting, standing with lights on and periods of idling and slow running, we considered at the time that we were safe in assuming that the battery would never reach such a high rate of charge in cases where the side lamps would be used. It would appear, however, from your note that the voltage is still rather on the high side and we will arrange to carry out further tests if you consider it necessary, in this direction. At present our lamps are rated 12 to 14 volts and it might be possible to raise the voltage of these from 14 to 16 volts if necessary. We should like to have your further comments on the matter. Hs{Lord Ernest Hives - Chair}/Wst. | ||