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 output and battery charging on 10,000-mile test cars.
| Identifier | ExFiles\Box 163\6\ img162 | |
| Date | 19th November 1931 | |
| X6016 G.W.Hancock from Hs{Lord Ernest Hives - Chair}/Wst. Hotel de France, Chateauroux, Indre. France. Hs{Lord Ernest Hives - Chair}/Wst.1/AD19.1131 X6016 X6106 DYNAMO OUTPUT ON 10,000 TEST CARS. Referring to your report of 16.11.31, we hope you are not using the discharge resistance too much during the daytime as it will be impossible for the battery to remain charged using the 60 watt headlamps for night running as no doubt you are doing. Owing to the reduced rate of charge during daytime running it is intended that the battery shall receive as much charge as possible during the day if there is any prolonged night running as there must be this time of the year. This is more especially the case where 60 watt head lamp bulbs are used. The whole idea of the half charge is to give reduced charge during the day and increased charge when it is most needed at night. We note from the daily reports of 19-GIV that 36 watt lamp bulbs were used so that there can be no comparison with this car as regards maintaining the battery. The dynamo fitted to 18-GIV is, with the exception of the grade of brushes, identical with that on 19-GIV, both machines having been built by production to the latest design. On our bench tests the 19-GIV dynamo had a lower cutting in speed than the 18-GIV machine but the former was considered to be better than the average (based on a number of similar dynamos we have tested). In return, however, 18-GIV dynamo gave a higher output at high speeds. Another point is that as you are keeping the battery volts low during the day the dynamo day charging rate is correspondingly reduced. In any case it is rather difficult to read the ammeter accurately at high speeds, and to alter the control brush will spoil the test as representative of T. series production. Hs{Lord Ernest Hives - Chair}/Wst. | ||