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 recorder graph displaying the results of an electrical test, including average amperes and ampere-hours.
| Identifier | ExFiles\Box 58\3\ Scan199 | |
| Date | 19th June 1930 | |
| 19-6-30 213/4 P4RRRN11-192 114 lbs 75 a.h. Average amperes = 6.48 Hours = 6.5 Ampere hours = 42.2 -37/ 1.80w | ||