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 manufacturer Peto & Radford concerning battery life testing methodologies.
| Identifier | ExFiles\Box 164\3\ img189 | |
| Date | 17th June 1938 | |
| CHILDS LONDON OFFICE 50 GROSVENOR GARDENS, S.W.1 TELEPHONE RAINHAM 34. (ESSEX) TELEGRAMS Manufacturers of Accumulators for over 50 years. PETO & RADFORD Proprietors - Pritchett & Gold and E.P.S. Company Ltd. WORKS DAGENHAM DOCK ESSEX. YOUR REF Rm {William Robotham - Chief Engineer} /RC {R. Childs} 18/JH. OUR REF. ESC/MH. {M. Huckerby} 17th June 1938. Messrs. Rolls Royce Limited, DERBY. Dear Sirs, We wish to thank you for your letter of the 10th instant, giving us particulars of a series of tests which you propose to carry out with a view to comparing future supplies of batteries, and we note that you will be letting us have a tabulated list of results in due course based on the tests. Referring to the question of an intensive life test on which you ask for our suggestions, this matter has previously been raised in correspondence between us in connection with tests carried out by you about two years ago. On that occasion we expressed some doubt as to the applicability of such tests for assessing the relative performance of batteries of different types, especially where the plate thickness varied from one type to another. It is impossible to devise an intensive life test which does not put undue emphasis upon one or other of the many factors involved in battery working, as the mere fact of speeding up the tests must tend to make them decidedly artificial. For instance, if the discharges are taken at the one-hour rate, as in the tests you were using, the battery does not really receive intensive working on the discharge side, but an attempt is made to compensate for this by giving about 33 1/3% overcharge, and by using a rather high charge rate. A test of this nature largely resolves itself into a test of the ability of the positive plates to withstand excessive charging, and we would stress the undesirability of making this one fact the criterion in selecting batteries for service on cars, especially as the present equipments fitted with voltage control effectively maintain a moderate input. Undue emphasis on this factor is particularly undesirable when comparing batteries of different types, containing | ||