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 the sustained potential difference of a P&R R.R.11-3 battery charging at various currents.
| Identifier | WestWitteringFiles\Q\February1927-March1927\ 3 | |
| Date | 9th February 1927 guessed | |
| SUSTAINED P.D ON A STANDARD P&R R.R.11-3 BATTERY CHARGING AT VARIOUS CURRENTS. VOLTS AMPERES. 20 16 12 8 4 0 0 2 4 6 8 10 12 | ||