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).
Dynamo battery system, electrical load calculations, and two-rate charging schemes.
| Identifier | WestWitteringFiles\V\October1930-February1931\ Scan153 | |
| Date | 19th December 1930 | |
| E.P.C. FROM E.{Mr Elliott - Chief Engineer} (struck through) C.c. to E.P.C. W.O.R. (struck through) C. to F.H. H.S. E.T. DYNAMO BATTERY SYSTEM TWO RATE CHARGE SWITCHING. X5780 X8780 X6016 Referring to the proposed one inter-connection scheme (EFC1/AD121230.) we feel that the operation of the switches would be difficult for the ordinary chauffeur to understand, and also that we cannot afford to reduce the dynamo output with full load on. This load is made up as follows: Head lamps........... 10.0 amps. Side & tail.......... 1.5 " Ignition............. 1.0 " Screen wiper......... 1.25 " Instrument board..... .5 " ---------------- 14.25 amps. There is nothing that can be left out of this list except the instrument board light. The screen wiper is often required for hours at a time on long wet night journeys when the lights should be at their best. If we abandon the 2 charge scheme as we have it then it will be necessary to reduce the dynamo output, and as, at the moment, its maximum value (at 14 terminal voltage) is only 12 amps. (EFC2/AD91230.) this appears inadmissible. It is desirable on the other hand that the dynamo should show a 'plus' charge with all load on (unless car going slowly) otherwise the headlamps will lose in illuminating power to an extent which can be fully appreciated when driving, and the battery will eventually run down if used for continuous night work in the country. R.{Sir Henry Royce} is not yet convinced that the dynamo itself need be enlarged, and in memo. R1/M13.12.30. makes suggestions for increasing the output. With regard to the lower rate of charge there is no doubt that this must be set quite high to cover the conditions of town driving in the winter and to obtain sufficiently early cutting in. In our original memo. E1/M241229. we advocate that the reduced charge should be three quarters of the then normal charge, and indicated that it would still be necessary to run on 'no charge' at times in summer to avoid overcharging. We note that the latest reduced charge curve No. 3. EFC///26.11.30 shows a maximum value of 10.5 amps. when plotted with relation to schedule terminal volts. We should be interested to see this curve plotted also at 14 terminal voltage. R1/M13.12.30. suggests a scheme to have full charge on for S. and T., as well as H.{Arthur M. Hanbury - Head Complaints} S. and T. Would the dynamo output have to be much reduced? This has the advantage of early cutting in. (1) | ||