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).
Criticizing the performance of a new type dynamo due to its inadequate charging rate at low speeds.
| Identifier | ExFiles\Box 163\6\ img073 | |
| Date | 25th November 1920 | |
| S/W EFC X6016. To Wor.{Arthur Wormald - General Works Manager} from Sg.{Arthur F. Sidgreaves - MD} re New Type Dynamo Sg{Arthur F. Sidgreaves - MD}14/E25.11.20 Copy to EFC. BY.{R.W. Bailey - Chief Engineer} referred to as the Hs{Lord Ernest Hives - Chair}/Rm.{William Robotham - Chief Engineer} PH. E.{Mr Elliott - Chief Engineer} "Half Charge" Scheme. X8780. When 58-GN, the car I am using, was last at Derby, Hs{Lord Ernest Hives - Chair}/Rm{William Robotham - Chief Engineer} fitted one of the new type dynamos which I understand it is proposed to standardise on the American chassis and on N.2. If the characteristics of the dynamo fitted to 58-GN are the same as it is proposed to fit as standard, then I am sorry to say that it is a failure and will, if adopted, lead us into a great deal of trouble and expense. The chief characteristic to which I refer is that it does not commence to charge until between 25 and 30 miles per hour and then at a comparatively low rate, i.e. about 4 or 5 amps. At night with just the side, tail and dashboard lamps on there is a continuous discharge below speeds of 30 miles per hour and at 30 only about 2 or 3 amps charge. Experience over the short time that it has been fitted shows the charging rate is quite inadequate for the purpose of keeping the battery charged on a car used chiefly for town work. My recollection is that the criticism which caused us to make the change was the one that for night driving in the country the dynamo was incapable of providing the necessary current, i.e. there was a discharge taking place the whole time of about 8 amps. Our dynamos have always been rather good on the point of providing a good charging rate at low speeds and if, as I mentioned above, the characteristics of the dynamo on 58-GN/ are the proposed new standard, I do not know why this big alteration has been made at low speeds. Possibly you would like EFC to come to town in order actually to try 58-GN. Meanwhile I feel that it would be as well to hold up any work in connection with [STAMP] EB RECEIVED 26 AUG 1920 | ||