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).
Letter from accumulator manufacturers Peto & Radford regarding battery charging rates and efficiency.
| Identifier | ExFiles\Box 61\1\ scan0022 | |
| Date | 27th March 1924 | |
| X265 Works, Dagenham Dock, Essex TELEPHONE VICTORIA 3667. 4 LINES PRIVATE BRANCH EXCHANGE. TELEGRAMS CONCENTRATION, SOWEST, LONDON. Manufacturers of P & R Accumulators. Established 1889 PETO & RADFORD Proprietors :- Pritchett & Gold and E.P.S. Company Ltd. 50 GROSVENOR GARDENS, LONDON, S.W.1. DIRECTORS: SIR ARCHIBALD C. GOLD WILLIAM PETO F.{Mr Friese} C. GRAHAM MENZIES C. R.{Sir Henry Royce} D.{John DeLooze - Company Secretary} PRITCHETT O.{Mr Oldham} R.{Sir Henry Royce} N. MINCHIN T. W. PRITCHETT. YOUR REF OUR REF M/C.273 27th March,1924. Messrs. Rolls-Royce Ltd. Nightingale Road, DERBY. Dear Sirs, For the attention of Mr.E.Fowler Clark. In reply to yours of the 21st inst. EFC1/T. re the 8 cells, we have spoken to our Works and they say that with regard to the Instruction Card which states "never charge at less than the minimum rate specified", our batteries are frequently owned, or operated by people who have little knowledge of electrical matters and less still of batteries, and for this reason our general instructions for the handling of this type of battery are drawn up to ensure, as far as possible, a satisfactory service and freedom from trouble and to protect ourselves should any arise. This instruction is obviously a useful safe-guard against the tendency to insufficient charge when low charging rates are employed. In your case however, where you have skilled attention and know as much about batteries as anybody, the position is different. Your proposal to operate your battery in the same way as a buffer battery with fluctuating falls of charge and discharge will be quite satisfactory, provided the discharge is not taken beyond a safe minimum voltage and the charge will be efficiently performed at from 4 to 40 amperes. The ampere hour efficiency is not appreciably effected by various rates of charge and discharge and may be taken as 90%. The discharge rate effects the watt hour efficiency, which is approximately 75% at the 10 hour rate, and approximately 69% at the one hour rate, when charging rates up to normal are employed. | ||