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).
Dynamo operation, battery charging circuits, and the functionality of an auto switch.
| Identifier | ExFiles\Box 59\1\ Scan241 | |
| Date | 31th January 1928 guessed | |
| -2- up and operate when hot. That is only if its original setting is too high. It can always be made to work certainly by keeping the figure down, and incidentally by so doing this will enable it to work more readily when the side lights are on, and so meet the point you mention. It is only a question of adjustment, and I think there is very little disadvantage in the fact that it may not sometimes work when side and tail only are on as in any case it is usually for a comparatively short period, and at most only a fraction of what it is at present. Regarding your last clause, if we make the resistance such that there is a small charging rate when the resistance is inserted, we at once lose to some extent the protection which is given us even at high speeds on open battery circuit. Altogether we now think there can be no question but that it is better to switch off the charge altogether, i.e. to use such an amount of field resistance that no operating speed of the dynamo can put up sufficient voltage to operate the cutout, although the machine is more or less excited. Yours sincerely, P.S.1. Auto switch. The real question at issue is as to whether a battery will gradually lose ground if the circumstances are such that the P.D. across its terminals can never rise above a figure which is determined by the setting of the instrument. When a battery is on charge at a fixed rate, say normal rate, the P.D. remains more or less stationary until towards the end of charge at which it rises, gradually. The functioning of the auto switch depends upon this final rise of voltage. We would like the operating point to be occur in the later stages of this pick-up in order to feel that the battery was getting more nearly what it would get on constant current charge. For safety of operation, however, we cannot do this, but we must choose a point lower down on this final rise of voltage, but not too near the horizontal portion. Is the functioning of the battery up-set to any extent, and if so, to what extent, by cutting it off before the final pick-up of voltage is effected ? That is what we do not know for certain. We think it possible that the battery may Cont.d | ||