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).
Analysis of the green lamp indicator for the battery charging system and its operational characteristics.
| Identifier | WestWitteringFiles\T\2January1929-June1929\ Scan228 | |
| Date | 8th May 1929 | |
| Contd. -2- EFC5/T8.5.29. of the green lamp switch unit to what we considered to be a suitable value, it had been stated that if the indications of the green lamp unit were followed consistently, the battery would not be maintained in a charged condition. We can now appreciate that in a general way this statement would be correct, i.e. on the assumption that the charging switch is not put on again during each non-stop run after once having been put off. If the green lamp switch is set to switch on at a reasonable voltage, i.e. a voltage indicating a suitably fully charged condition of the battery when the battery is warm, this voltage is a figure which appears, in general, to be on the low side. Were we to make the figure higher, then the green lamp would never become lit in ordinary warm running conditions. The result of the lower setting is that when starting up from cold and particularly due to the fact that the dynamo output is somewhat greater at that time, it may be expected to occur, and actually does occur, that the green lamp lights up very soon after the car has been started - moreover, this is the case in spite of the fact that what appears to be a considerable discharge may have been taken from the battery to operate the starter before a start has been effected. In view of the above, it appears to us that satisfactory control of a system, utilising the green lamp scheme, stilll requires intelligent control on the part of the driver as in the case when the green lamp arrangement is not there. | ||