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).
Half-charge switching idea for managing dynamo output and battery overcharging.
| Identifier | ExFiles\Box 165\6\ img250 | |
| Date | 27th December 1929 | |
| -2- EFC3/AD27.12.29 contd. In our EFC5/T26.7.28 we referred to the half charge switching idea, which is now again to the fore, in the following terms :- "One other point - many people advocate the use of a dynamo field resistance unit incorporated in the headlamp switch in such a way that at no time when the headlamps are not in use can the dynamo give more than half its normal output. When the headlamps are put on, this field resistance is short circuited and full output is given. There appears to be a good deal to say for this method of controlling the overcharging and I think it is one which the battery makers themselves would favour We do not know to what extent you have considered this means. The disadvantage would appear to be the non- availability of the full output for quickly charging up the battery in circumstances when this is necessary." This would be a half measure in that it would not cater for (1) above, and would only half cater for (2) and (3). It is considered that it would be in this case, possible to increase the output at moderately high speeds by say 10% on account of the improbability of any driver leaving the switch on the full charge rate for any considerable time. An onus would be on the driver not to forget his half charge rate because if he did there would be some risk of dynamo overheating. As previously pointed out with automatic control a full 20% more than at present would be permissible. You will gather from these remarks and what we have quoted above, that we are in favour of this suggestion as a partial measure. It would however, mean a considerable change of design in the switching system and connections, particulars of which I shall | ||