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).
Comparison of P & R and Exide batteries and an analysis of generator output characteristics.
| Identifier | WestWitteringFiles\O\2April1926-June1926\ Scan245 | |
| Date | 26th June 1926 | |
| Contd. -2- EFCl/T26.6.26. P & R batteries are systemmatically higher in P.D. and E.M.F. than the Exide. Messrs. Peto & Radford have, however, recently been working on this problem considerably and have informed us that they have reduced this charging P.D. and E.M.F. to a figure which would appear to correspond almost exactly with that of the Exide. The true internal ohmic resistance of the battery is estimated by taking the volt/ampere slope of the P.D. curve using the E.M.F. curve as a base line. This resistance does not seem to differ to any large extent in the 40/50 batteries, but is clearly a little larger in the case of the 20 HP. batteries. It is particularly interesting to note that the true E.M.F. at the higher rates of charging current may be considerably more than the sustained P.D. at the lower charging rates. On the standard 40/50 P & R.{Sir Henry Royce} RR111 curve a line AB has been drawn representing the volt-ampere output characteristic of an externally controlled generator, controlled electro-magnetically to an output at the distribution board of V + .25A = 17 i.e. to an output which is 17 volts on open circuit with one volt reduction of the voltage of the system for every 4 amperes of current delivered by the generator. As stated the generator output is assumed to be controlled to this characteristic at the distribution board and the ohmic resistance of the wires from the distribution Contd. | ||