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).
Letter detailing the investigation into battery ignition point failure due to excessive voltage.
| Identifier | ExFiles\Box 70\3\ scan0149 | |
| Date | 27th May 1926 | |
| X8783 (COPY) "Moreton", Holly Place, Hampstead. 27th May, 1926 X8780 X8783 Dear Mr. Northey, I have at last discovered the reason why the contact points of the battery ignition give up the ghost after 1000 miles running. I therefore pass the information on for your consideration as I think the following tests leave no doubt as to the origin of the trouble. Tests on battery terminals made with Weston Voltmeter known to be absolutely O.K. gave the following interesting results :- With charging switch off 12.5 volts With dynamo charging voltage quickly rose within a few minutes to 17.5. volts. Electrolyte was then weakened and also strengthened, results the same. Electrolyte of known spec. gravity 1250 then put into battery after throwing old electrolyte away. Result still this excessive voltage 17.5 at battery terminals immediately charging switch was put on. I then made tests with C.A.V. battery of same capacity known to be in perfect condition with electrolyte at same specific gravity, viz.1250 . Result the same rise of voltage from 12.5 to 17.5 immediately dynamo charged. | ||