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 battery performance in a 40/50 system, noting internal resistance and voltage figures.
| Identifier | ExFiles\Box 57\1\ Scan021 | |
| Date | 15th January 1926 guessed | |
| -22 Contd. Again the P & R battery showed the highest internal resistance, the resulting voltage being higher than that found in the 40/50 system. The Exide voltages also exceed the 40/50 Exide figures. FJA. | ||