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 an accumulator manufacturer regarding battery testing procedures and comparative results.
| Identifier | ExFiles\Box 164\3\ img200 | |
| Date | 22th July 1938 | |
| TELEPHONE RAINHAM 34. TELEGRAMS (ESSEX) LONDON OFFICE. 50 GROSVENOR GARDENS, S.W.1 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} 15/JH. OUR REF ESC/7. CHILDS -> 22nd July, 1938. Messrs. Rolls-Royce, Ltd. Experimental Department, DERBY. 6021 Dear Sirs, Further to our letter of the 7th acknowledging your letter of the 5th, we are pleased to note that the experimental 6.HZD11.G battery has given very good results as compared with the other types which you tested. We are arranging to send to you a Dagenite 6.GLK11 battery so that you can test this and compare it with the results obtained from the Lucas 12.TXW11 battery. The 6.GLK11 type is our correct replacement for this Lucas type. With reference to a suitable life test which you can apply to batteries, we appreciate the difficulty you mention of making and calibrating a suitable discharge resistance and automatic switch, and we should much prefer to see the discharges carried out during the day under supervision, leaving the charging to be done at night. A Sangamo ampere-hour meter fitted with an automatic switch would enable the charge to be cut off at the stage when 10 per cent. overcharge had been given, and providing the instrument is occasionally checked for accuracy, the charging could be safely left without supervision and could therefore be done at night. The rate of charge would fall off as the back E.M.F. of the battery rose, but not to any serious extent if the supply voltage is well in excess of the battery voltage. The proposed 7-hour discharge rate would be quite suitable and would conveniently fit into the working day of 9 hours. | ||