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).
Chart recording of an electrical test, showing amperage over time.
| Identifier | ExFiles\Box 58\3\ Scan175 | |
| Date | 2nd February 1931 | |
| 2-2-31 226 P&RTBD7E-16 50 a.h. 81 lbs. Average amperes : 5.0 Hours = 11.2 Ampere hours = 56.0 .691 2.34 | ||