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).
Weighing the pros and cons of magneto ignition versus double battery ignition.
| Identifier | ExFiles\Box 32\5\ Scan090 | |
| Date | 7th January 1931 | |
| X6096 R.{Sir Henry Royce} from E.{Mr Elliott - Chief Engineer} c. Sg.{Arthur F. Sidgreaves - MD} Wor.{Arthur Wormald - General Works Manager} c. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} E2/M1 7.1.31. X.6096/7/9. MAGNETO IGNITION+ X.6105. Referring to Hsl/MJL4.1.31 we have at WW. for some time past been weighing up the pros and cons of magneto ignition. It has always been supposed that in the event of a failure of the battery ignition (not the battery) it would be possible to start the car and run as before on the magneto, which must have proved to be the case in connection with the failure of the ignition coil we experienced previous to the recent improvement of this component. The same advantage, however, is secured by the use of double battery ignition as it is not likely that both coils would fail simultaneously, and this applies also to the other components of the ignition material. We do not think it is practicable to duplicate the system to the extent of having two batteries, so this brings us down to the point that we should be dependent on one battery. There is no doubt that the battery will run on the ignition and lights even when it is in a very bad state and unable to start the engine. Ignition coils are expected to operate on a low potential to cover the voltage drop when electrical starting, and this enables a certain hand start to be obtained when the P.D. of the battery is a long way below normal. The owner is, therefore, not likely to get stranded and will have time to arrange for replacements and repairs. The magneto on the other hand demands some special device such as an impulse starter to get a big engine going by hand, and is also an awkward unit to instal and drive. Moreover it assists in rendering the production of a left hand chassis more difficult. E.{Mr Elliott - Chief Engineer} | ||