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 Peto & Radford detailing the comparative test results of an Accu-Slem cell against an R.R.11 cell.
| Identifier | ExFiles\Box 54\1\ Scan015 | |
| Date | 2nd April 1925 | |
| X46171P COPY OF LETTER FROM PETO & RADFORD, 50, GROSVENOR GARDENS, LONDON. S.W.1. M/S. 2nd. April, 1925. Messrs. Rolls-Royce Ltd., DERBY. For the attention of Mr. Fowler Clark. Dear Sirs, X46171P X4558 You will remember you sent us some long time ago a single "accu-Slem" cell which had been in use for 23,000 miles, which was agreed by all to be in very good condition. You then sent us a new cell and asked us to test it against one of our latest R.R.11 cells and the following is what our Works report :- "The Accu-Slem 11-plate cell sent to us from Rolls-Royce, Derby, was tested in series with one of our standard RR.11 (11-plate cells) and given 61 complete discharges before dismantling for examination. The charging rate was 6-8 amperes and the input 50% in excess of the output. At low rate discharges the Accu-Slem gave a maximum output of 70 ampere hours, i.e. 6.5 amperes for 10.8 hours and the R.R.11 gave 83 hours, i.e. 6.5 amperes for 12.8 hours. Discharged at 150 amperes the Accu-Slem gave 7.9 minutes and the R.R.11 10.8 minutes. After 45 discharges the Accu-Slem output fell off to 59 ampere hours discharging at 6.5 amperes and cadmium electrode indicated positive weakness. After 56 discharges the R.R.11 fell off to 64 ampere hours, the cadmium electrode indicating negative weakness. After 61 discharges the Accu-Slem output was 43 ampere hours, cadmium values indicating pronounced positive weakness and a certain amount of negative weakness, whilst the R.R.11 output was 55 ampere hours with cadmium values indicating negative weakness and good positive performance. On examination, the Accu-Slem positives were found badly worn and expanded with some grids cracked on the rim. Positive active material was adhering to the wood separators which were in a rather fragile condition. Contd. | ||