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).
Investigation into a failed ignition coil on chassis 101-UF, detailing electrical faults and concluding the cause was an open battery circuit.
| Identifier | ExFiles\Box 70\3\ scan0138 | |
| Date | 10th October 1929 | |
| By.{R.W. Bailey - Chief Engineer} from EFC. c. Hm{Capt. W. Hallam - Head Repairs}/AVS. c. N. X8783 cl. EPCI/AD10.10.29. X8710. IGNITION COIL CC.35X. EX CHASSIS 101-UF. With reference to the ignition coil CC.35X. which failed on the above chassis and has been found on dis-assembly to have a charred primary, it is important in this connection for us to know the condition of the ballast resistance which was in use on the car at the time of failure of the coil. Can you obtain this ballast for us for our inspection? From Hm{Capt. W. Hallam - Head Repairs}/AVS/KW7.10.29, which by the way, does not state whether the car is a 20 HP. or a 40/50, it appears to be the case that running of the car has taken place with the battery dis-connected from the system, the following being the points of evidence as given by that memo:- (1) Short circuits have occurred. (2) It was necessary to replace lamp bulbs which presumably had burnt out. (3) Gauge lamp contacts were damaged. (4) Fuses (or fuse) had blown when starting up from cold. This would probably be the field fuse although that is not stated, and this is what would be expected if the battery became dis-connected shortly after starting. N.B. The result of examination for cause of blowing fuses not stated. (5) Battery positive wire to starter main switch and distribution board had to be replaced as if this was damaged by heavy current, which blew emergency fuse. (6) Distributor platinum points were found to be badly pitted as would be the case if the ignition system were subject to an over-voltage. It is fairly clear on the above evidence that the reason of the charring of the coil has been an open battery circuit. It is impossible for the primary winding of the coil to char when everything is right on the system. We have established this by experiments beyond any doubt. | ||