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).
Battery test chart for a B.A.V. Willard 12XR3 battery from chassis 57.S4.
| Identifier | ExFiles\Box 47\4\ Scan042 | |
| Date | 6th January 1925 | |
| X4414V B.A.V. Willard 12XR3 Battery from Chassis 57.S4. 6-1-25 66 lbs. 47.5 a.h. REGD TRADE MARK Average amperes = 5.3 Hours = 2.38 Ampere hours = 12.4 788. 2.3kw. 03 82 x4414V | ||