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).
Graph showing sustained potential difference (P.D.) during battery charging at various currents.
| Identifier | ExFiles\Box 54\1\ Scan144 | |
| Date | 10th August 1927 guessed | |
| VOLTS. SUSTAINED P.D ON A STANDARD P&R R.R11-3 BATTERY CHARGING AT VARIOUS CURRENTS. AMPERES. | ||