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 discussion on battery and starter motor performance, referencing previous reports and tests.
| Identifier | ExFiles\Box 168b\2\ img064 | |
| Date | 13th September 1921 | |
| -4- Contd. EFC1/T13.9.21. any battery it is desired to try need only be connected up, the reading taken immediately and its condition ascertained, the relative condition of the several cells being ascertained if necessary with a cell voltmeter at the time of discharge. Referring to Mr. Olley's note Cy4/G8.4.21, we note in the middle paragraph on the second page that, as suggested in our report EFC5/T8.9.21, the substitution of a motor with windings of higher resistance actually increased the speed at which the engine was turned in the case of a bad volt-ampere characteristic of the supply to the motor. With reference to Mr. Olley's curves of terminal voltages at motor obtained with various batteries and starter cables on the R-R car, we think that the S.A.E. standard motor terminal volt characteristic is a good deal better than would be normally obtained with battery and starter cables of reasonable weight. The curves given by Mr. Olley as representing actual results no doubt represent conditions when the battery is insufficiently charged. The virtual internal resistance of any battery, however, increases materially as the acid density is reduced, and taken allround, we are of the opinion that the testing of the starter motors on this characteristic would make the performance of the motor appear much better on the bench than it is likely to be on the car. We still think our own assumed characteristic Contd. | ||