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 'Half-Charge Scheme' on 20/25 HP models, detailing the risks of modifying the dynamo field resistance.
| Identifier | ExFiles\Box 163\6\ img254 | |
| Date | 3rd January 1933 | |
| WST see X6266 Hs{Lord Ernest Hives - Chair} c - Hs.{Lord Ernest Hives - Chair} BY/RD2/W.3-1-33 Re :- Half-Charge Scheme on 20/25 H.P. (Hd{Mr Hayward/Mr Huddy}/SB{Mr Bull/Mr Bannister}7/MW.21-12-32) Dealing with the question of dynamos used with the half-charge scheme, we are of the opinion that if the field resistance is definitely short circuited, it is possible for the condition to arise whereby the dynamo fully charges the battery and would then be a danger to itself because it may "throw its solder". In cases of complaint of under-charging, we recommend that our smaller field resistance, of which you have already had several, should be fitted and at the same time we think it advisable to notify the customer that with the greater charge rate which is now provided there is much more liklihood of over-charging taking place during long runs, with the resultant "topping up" of the batteries being more frequently required. Summing up, therefore, we say that :- (a) short circuiting the resistance will most likely damage the dynamo. (b) the smaller resistance will merely provide the customer with the inconvenience of having to pay more attention to his batteries in the summer time, or on long runs, but will not endanger the dynamo. BY/RD. | ||