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).
Listing the weights of various batteries and the capacity of the De Martis battery.
| Identifier | ExFiles\Box 49\5\ Scan271 | |
| Date | 7th March 1921 | |
| Contd. -6- EFC {E. Fowler Clarke - Electrical Engineer} 3/T7.3.21. The weights of these batteries are as follows :- Improved British Exide - 79 1/2 lbs. R.R. Tudor. - 90 lbs. U.S.A. Exide. - 85 1/2 lbs. De Martis. - 76 1/2 lbs. The rated capacity of the De Martis is 70 ampere-hours. Those of the others are not given. Particulars of the costs of these batteries will be sent within a day or two. EFC. {E. Fowler Clarke - Electrical Engineer} | ||