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).
The performance and adjustments made to a 12-volt dynamo system, focusing on contact sparking and circuit resistance.
| Identifier | ExFiles\Box 38\3\ Scan015 | |
| Date | 14th May 1920 | |
| Contd. -2- 18 EFC2/T14.5.20 performance on 12 volts with the added resistances is quite as good as on 6, there seems to be a tendency to rather greater sparking on the vibrator contacts, especially when the speed is only just above the speed at which these contacts begin to operate, namely, about 1200 R.P.M. at higher speeds of about 1450 R.P.M. however, this sparking appears to be quite reasonable. We have arranged the driving pulley for the engine shaft so that the dynamo will be driven at about 1400 to 1500 R.P.M. which we think will be O.K. It will be noticed that we have shown on the diagram a small resistance in the battery circuit to improve the operation of the regulator. We have found this is rather necessary on 12 volts with the other resistances in their variouscircuits, because if we do not have it, and unless the leads have some little appreciable resistance, the battery charging current rises to about double or even more than its normal value when the contacts are operating, before the contacts begin to operate. (We are sending the resistance). This slight resistance just puts this matter right because it allows a bigger voltage variation at the dynamo end, and therefore a reduced sensibility in the adjustment of the vibrator contacts. We have had made a little key (which we send) by which both the adjustment of the vibrator contacts and of the cut-in contacts may be made. We have left these adjustments, as we think, about right for charging a 12 volt battery, but it will be a simple matters | ||