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).
Cold starting tests comparing different batteries and ignition coils on various chassis, concluding with a recommendation.
| Identifier | ExFiles\Box 151\3\ scan0364 | |
| Date | 4th February 1938 | |
| -4- Rm {William Robotham - Chief Engineer} /Gym.1/MH. {M. Huckerby} 4.2.38. With the Wraith battery fitted the engine would not start, the Bentley battery started it after 10 secs., the P.III 4 secs. and the 25/30 H.P. in 4 secs. A test was then taken with the 25/30 H.P. battery and R.R. 20,000 turn coil and resistance. A fairly satisfactory start was made after 7 secs., but not so convincing as with the Delco coil. On a check test with the 25/30 battery and R.R. coil and resistance on 25.G.VI we had to fit the Delco coil before a start was made. The extra weight and cost of the 25/30 battery are points against its use, but we consider with the present lay out of the Wraith, it is necessary along with the Delco coil to give a satisfactory start at 8°F. {Mr Friese} We have also carried out comparative cold starting tests with 28.G.VI and two present standard 30 H.P. chassis. Standard 30 H.P. batteries were used for the tests. 28.G.VI would fire but not continue to run using R.R. 20,000 turn coil, plug gaps .030". A good start, however, was obtained by fitting the Delco coil. On the first 25/30 H.P. chassis tried, the engine would not fire although turning over at 60 R.P.M., but the second chassis fired almost immediately and continued to run after several attempts. This shows a decided variation in the starting of two production chassis. From all the tests taken we recommend the fitting of the 25/30 H.P. battery in conjunction with the Delco coil for cold starting. This battery is better than either the Bentley or the previously proposed Wraith as shown by the figures, and is on a par with the P.III with the advantage of approx. 13 lbs. less weight. Rm {William Robotham - Chief Engineer} /W.Brazier. | ||