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).
Comparative analysis of C.A.V. and R.R. engine starting systems, focusing on battery performance and virtual resistance.
| Identifier | ExFiles\Box 50\2\ Scan107 | |
| Date | 13th February 1922 | |
| Con'd. {John DeLooze - Company Secretary} -2- EFC {E. Fowler Clarke - Electrical Engineer} 2/T13.2.22. Both engines were then started and allowed to warm up. Owing to the greater starter speed of the C.A.V. system, it was possible to start the engine on the magneto without the battery ignition being switched on. The figures for the hot condition with the water at 80°C were now, for the C.A.V. system (average of two starts):- Volts Battery 10.71 Motor 10.43 Amperes, 86 Engine revs. 95 r.p.m. Motor revs. 1040 For the R.R. system (84°C) on 1 EX :- Volts Battery 10.11 Motor 9.55 Amperes, 62 Engine revs. 60 Motor revs. 1400 The virtual battery resistances reckoned on the loss of battery volts from 12 volts, are, in the C.A.V. case .014 ohm cold and .015 ohm hot. These figures are just nicely within our suggested limit for battery resistance, .015 ohm, reckoned as the loss of volts from 12.00 volts per ampere. In the R.R. case, the figures for the virtual battery resistance are .021 ohm (cold) and .030 ohm (hot). It is evident from these figures that the P & R. {Sir Henry Royce} B.L.11 battery was not really in a suitable state of charge for the comparative test, therefore the figures show up too advant- ageously in favour of the C.A.V. We know, for instance, from bench tests (see curves) that the P & R. {Sir Henry Royce} B.L.11 battery is capable of delivering this number of amperes for 6 minutes with a virtual resistance within our limit (.015 ohm) if in a fully charged condition. Contd. | ||