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).
Modification to the 20/25 Dynamo to improve winter battery charging.
| Identifier | ExFiles\Box 62\3\ scan0317 | |
| Date | 10th January 1933 | |
| X6005 E.{Mr Elliott - Chief Engineer} From Hs{Lord Ernest Hives - Chair}/Wst. By.{R.W. Bailey - Chief Engineer} c. Sg.{Arthur F. Sidgreaves - MD} c. Wor.{Arthur Wormald - General Works Manager} c. EP.{G. Eric Platford - Chief Quality Engineer} c. HO. C. MX.{John H Maddocks - Chief Proving Officer} Hs{Lord Ernest Hives - Chair}/Wst.2/KT.10.1.33. PRESENT STANDARD 20/25 DYNAMO. For some time now we have been aware that the charging conditions of the present standard 20/25 have been unsatisfactory for winter running conditions. The trouble has been due to the fact that the amount of charge received by the battery during the daytime is insufficient for winter running conditions to maintain the excessive lamp and starter discharges. In order to meet complaints, and to ensure that the battery remains reasonably charged, we have decided to recommend that the dynamo field resistance be halved, i.e. 11 ins. Reducing the value of the resistance by this amount gives a much better day charging current and also safeguards the dynamo from any damage due to overheating. We attach herewith blueprints shewing the curves of the dynamo with the proposed modification to the field resistance. We recommend that in cases of complaints in the Repair Dept. and elsewhere, customers be supplied with this new resistance, and also for the remaining chassis which have yet to be made at the Works with the two-rate charge scheme fitted, this resistance should also be fitted immediately. It will be remembered that we have standardised the 3 rate charge system for future 20/25 requirements. Hs{Lord Ernest Hives - Chair}/Wst. | ||