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).
Description of an electrical relay device that controls accumulator charging based on voltage levels.
| Identifier | ExFiles\Box 59\1\ Scan359 | |
| Date | 29th April 1930 guessed | |
| (2) become charged their voltage rises, depending upon the rate of charge and as the rate of charge on all modern electrical equipment is for practical purposes constant, on the average about eight amperes, the voltage rise of the cells denotes the state of charge. Similarly the voltage of the cells under a constant discharge also indicates the state of the cells. Now with my device as soon as the voltage of the accumulator rises to a set voltage, i.e. the voltage of the accumulator when fully charged when receiving a charging current of the dynamo's full output, the relay operates and either switches the charging rate to "Half Charge" or switches off the charge altogether. As soon as the charging rate is lowered, or stopped, the voltage of the cells of course drops to their "idle voltage", but this does not affect the relay as when it operates it automatically "cuts itself out" and does not come into operation again until either (1) the engine speed becomes so low that the dynamo is unable to generate the necessary power to hold the relay closed, or (11) the lights are switched on. In Case No. 1. the relay will naturally automatically work againas soon as the engine speed rises sufficiently to cause the battery voltage to rise to the set voltage. In Case No. 11. the relay would allow the battery to receive full dynamo output as long as the discharge was heavy enough to keep the cells below the set voltage, but a small discharge such as a "Stop" sign light connected to a brake would not be sufficient to switch the dynamo back on to "Full Charge" unless the engine speed was caused to drop as above. | ||