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 a battery manufacturer discussing charging voltages and characteristics.
| Identifier | ExFiles\Box 54\1\ Scan104 | |
| Date | 6th July 1926 | |
| X4617P Works, Dagenham Dock, Essex. TELEPHONE VICTORIA 3667. 5 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 E.C. GRAHAM MENZIES O.R.N. MINCHIN WILLIAM PETO C.R.D. PRITCHETT T.W. PRITCHETT. YOUR REF. _______ OUR REF. M/5. 6th July 1926. E.{Mr Elliott - Chief Engineer} Fowler Clark Esq., Messrs. Rolls Royce Ltd., DERBY. Dear Fowler Clark, With reference to your note of the 26th June re battery voltages, this has been read by our Works and Mr. Preston says that if you take one of our latest production batteries you will find that they have a P.D. of approximately 2.70 volts per cell when charging at 12 amperes. As regards the effect of a tapering charge with a generator output in accordance with the line Ab on the curve, he considers that such a type of charge would be adequate and efficient and calculated to prolong the life of the batteries. I am still of the opinion that the charging current could be further reduced without any fear of the battery running down. The generator on my car is supposed to have a slightly lower output, I believe, than standard and I find that it is more than enough to keep my battery fully up in spite of the fact that I switch it off for quite considerable periods, which I do not think the ordinary driver ever does. I see that your curves do not go above 12 amperes but the charging current on the car does do so, and the Exide voltage seems to be still on the rise at that point whereas ours is a flatter curve. I am going to take one cell out of my battery and run it on five cells to see what happens. If these systems are really designed for 12 volts, one will get more than 12 volts out of five cells and it may be interesting to see what happens. I spoke of | ||