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 comparing the sustained potential difference of P&R and Exide 6-volt batteries during charging.
| Identifier | ExFiles\Box 168b\3\ img076 | |
| Date | 22th January 1930 | |
| TERMINAL P.D. TIME (HOURS) P&R EXIDE CURVES OF THE SUSTAINED P.D. ON A 6 VOLT P&R BRNII BATTERY AND A 6 VOLT EXIDE 3BR5-IEL BATTERY WHILST CHARGING AT 10 AMPERES WITH THE BATTERY FULLY CHARGED AND THE TEMPERATURE RISING FROM 50°F TO 110°F.{Mr Friese} H.J. | ||