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).
Letter discussing vehicle electrical systems, specifically charging rates, automatic switches, tail lamp indicators, and ignition points.
| Identifier | ExFiles\Box 59\1\ Scan138 | |
| Date | 28th April 1927 guessed | |
| -2- Contd. considered as a switch for switching off the system when not in use. Apparently you consider that even with the automatically reduced rate of charge it would still be desirable to switch off all charge while running. I think we sent you a curve of the reduced rate of charge as reduced by the insertion of the automatic switch (we also sent you a curve of reduced rate of charge as given by your special dynamo), and in view of the fact that the battery ignition has always to be subtracted from this, it can scarcely be considered that the nett charging current of the battery would be so large as to make it desirable to switch it off. In any case it would be possible, by the introduction of still more resistance, to reduce the charge still further. I think that if it was considered still necessary to switch off the charge, we should be losing one of the advantages of relieving the driver of the onus of keeping in mind the necessity of this operation. Actually, on our two experimental cars fitted with auto switch, it is noted that the thing is working on reduced rate of charge nearly the whole of the time, which supports your observation that the demand on the system is a good deal smaller than that supplied by the dynamo with the standard arrangement. As regards what Mr. Royce thinks of the whole thing, I think he must come round to it eventually, but at the moment he is suggesting other arrangements, one being that the electro-magnet coil operates an 'on' switch for a green light, so that the automatic operation is transferred to the human element. I do not like that idea. With regard to the tail lamp indicator, what I thought you would say was that it would be a definite advantage to utilise the tail lamp relay as a buzzer in the daytime, when the thermometer contacts close, at which time the red lamp would not be so easily seen, and that therefore the arrangement as depicted in Fig.1 was precisely what was required, and it is quite true that this could be probably satisfactorily arranged to act in this way. In regard to your last paragraph, we are asking Mr. Whitehead to enquire if Messrs. Lucas would be willing to fit their special points to one or two of our battery ignition contact breaker levers and screws. It is interesting that your Lucas magneto continues to operate as satisfactorily as you state. Yours sincerely, | ||