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).
Trade-offs of using higher output dynamos, including charging rates and battery life concerns.
| Identifier | ExFiles\Box 60\3\ Scan108 | |
| Date | 1st February 1929 | |
| To R.{Sir Henry Royce} from EFC. c. E.{Mr Elliott - Chief Engineer} Da.{Bernard Day - Chassis Design} c. SG.{Arthur F. Sidgreaves - MD} CWB. c. PN.{Mr Northey} WD.{Mr Wood/Mr Whitehead} DYNAMO OUTPUT. The higher output dynamos (20 H.P. and 40/50) as at present arranged give a very considerable increase of output over the standard, and moreover their output does not fall so much relatively at the high speeds. At the same time their cutting in speed is materially increased, i.e. 35 to 40% higher. This latter would to some extent be counteracted by the 10% increase in engine speed in relation to the road speed. Standard peak charging rates are - 40/50 H.P. 12 amperes at 24 m.p.h. 20 H.P. 11 amperes at 23 m.p.h. and higher output rates are - 40/50 H.P. 15 amperes at 35 m.p.h. 20 H.P. 15 amperes at 30 m.p.h. We should say that we could not satisfactorily adopt as standard the higher output dynamos as at present arranged without considerable danger of premature deterioration of batteries. Batteries are now a good deal better on overcharging at normal rates, but we are of the opinion that a considerable reduction of life would result from uncontrolled charging with the higher output machines and we feel sure the battery makers would not approve. It is readily possible to reduce the output of the higher output machine to half way between the standard curve and the higher output curve, but we should not realise any decrease in cutting in speed by so doing. | ||