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).
Proposal for chassis wiring to protect batteries against over-discharge using a master switch system.
| Identifier | ExFiles\Box 179\2\ img214 | |
| Date | 2nd February 1932 | |
| To R.{Sir Henry Royce} from Hs{Lord Ernest Hives - Chair}/ust. c. Cox. Sg.{Arthur F. Sidgreaves - MD} c. E.{Mr Elliott - Chief Engineer} De. c. R.{Sir Henry Royce} Cx.{Major Len W. Cox - Advertising Manager} ORIGINAL. Hs{Lord Ernest Hives - Chair}/ust.1/ADO.2.32. X6082 X7741b R.R. CHASSIS WIRING. We are sending you herewith a diagram showing a suggestion we have in mind for the protection of our chassis batteries against overdischarge which must be avoided at all costs where battery ignition alone is relied upon Firstly we would propose the complete isolation of all electrical accessories on the chassis by means of a master switch on the instrument board. This switch would control four circuits through four fuses on the distribution board. These four circuits as per A's suggestion would then be distributed to two junction boxes one at the front of the chassis and one at the rear for the purposes and convenience of coachbuilders when electrical accessories are required on the car. One wire to each junction box would be for heavy current circuits such as starter motor tester and relay circuits, cigar lighters, body heaters, electric petrol pumps etc. and the other wire for light current circuits such as would be required for horns, windscreen wipers, direction indicators, stop lamps, instrument board lights and body lights etc. All the electric circuits, however, would come through fuses located on the one distribution board thus considerably simplifying trouble diagnosis and allowing us to dispense with accessory distribution boards. So that this master switch shall always be switched off along with the ignition switch when leaving the car, we propose that it be coupled up to the same red warning lamp as will be used to indicate when the ignition switch has been left on. This would necessitate two contacts which would normally be opened when the engine is running but would make contact to a common contact plate connected to the warning lamp when the engine is at rest. These contacts could, of course, be operated on the back of the cut-out but we suggest that if they were operated by a small diaphragm connected up to engine oil pressure, the cut-out and regulator unit (on J.S) would be simplified and the warning lamp would also serve to indicate a failure of oil pressure. | ||