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 chart recording of a battery performance test.
| Identifier | ExFiles\Box 58\3\ Scan198 | |
| Date | 20th October 1930 | |
| 20-10-30 224 P&R & Exide N.S.1. 75a.h. 111 lbs. Average amperes = 6.41 Hours .9.5 Ampere hours = 60.9 .540 1.80w | ||