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).
Performance specifications for output current at 13.0 volts under cold and hot conditions.
| Identifier | ExFiles\Box 142\1\ scan0019 | |
| Date | 28th October 1937 | |
| -3- Rm{William Robotham - Chief Engineer}/CAP.11/MH.{M. Huckerby}28.10.37. Output Current at 13.0 Volts. Cold. Specified. 14.0 to 16.5 amperes. Lucas unit 10.8 " (Average for whole without compensation. range of speed) Unit with 16.0 " " " " compensation. Output Current at 13.0 Volts. Hot. Specified. 15.0 to 18.5 amperes. Unit without 16.7 " (Average) compensation Unit with 11.5 " " compensation. The difference between, for example, the value 10.8 amperes cold, and the corresponding hot value of 16.7 amperes, due to heating up, is excessive, and indicates we think, undue internal heating of the shunt winding. The effect of the temperature compensating device, is shown in the drop from the value 16.0 amperes cold, to the corresponding value, hot, of 11.5 amperes. Repeated attempts have been made to reduce the amount of compensation, but this apparently, cannot be carried any further without weakening the unit mechanically. (c) Under day-running conditions, when the battery is fully charged, and the ignition and petrol pumps are the only load on the system, the battery charging current should not be more than about 3 amperes. Like the night-running load, this is subject to variation due to rise in temperature, and at present we have to accept a wider range of variation than we like. | ||