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).
Technical memorandum discussing the voltage rise on the electrical system and its effect on lamps.
| Identifier | ExFiles\Box 163\6\ img161 | |
| Date | 1st November 1931 | |
| Y6016 By.{R.W. Bailey - Chief Engineer} from Hs{Lord Ernest Hives - Chair}/Pgt. Hs{Lord Ernest Hives - Chair}/Pgt.1/ADL.O.11.31. VOLTAGE RISE ON ELECTRICAL SYSTEM. In connection with the point raised by By/RD. as to what margin of safety we have from burning out the side and tail lamps when running with these lamps only on. This is in view of the fact that with the present two-rate charge scheme, the full output comes on with the lamp-switch in the S & T position, and owing to the small load on the battery, the voltage of the system rises higher than is otherwise possible. From tests we have made we can say that the maximum voltage ever likely to be applied to the side and tail lamps is about 16.25 in the case of the 40/50 and 16.5 for the 20/25 chassis. The standard lamps are rated at 12 to 14 volts, so that in the extreme case the lamps would be over-run to the extent of 2.5 volts. In order to arrive at this extreme case the battery would have to be fully charged and gassing, four watt lamps used in the S & T positions, and the car run at a speed corresponding to the peak output of the dynamo, i.e. about 27 m.p.h. and 30 m.p.h. for the 40/50 and 20/25 respectively. 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 think we are safe in assuming that the battery cannot reach such a high state of charge. In addition it is probable that six watt lamps will be fitted and instrument and body lights used more. Hs{Lord Ernest Hives - Chair}/Pgt. | ||