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 discussing modifications to battery plates and experiments with ebonite and wood separators.
| Identifier | ExFiles\Box 54\1\ Scan085 | |
| Date | 2nd February 1926 | |
| X4617P COPY OF LETTER FROM:- PETO & RADFORD, DAGENHAM DOCK, ROMFORD, ESSEX. KP/4. 2nd. February, 1926. E.{Mr Elliott - Chief Engineer} Fowler Clark Esq., Messrs. Rolls-Royce Ltd., DERBY. LL655 Dear Mr. Fowler Clark, X.4617P. X.3839. I am pleased to inform you that by adopting certain modifications in the method of producing the active material in our plates, we are now able to supply you with batteries for the 40/50 R.R. which give a P.D. of approximately 2.70 volts per cell when charging at 12 amperes. During the course of our investigations relative to the reduction of internal resistance on charge I have also borne in mind the importance of maintaining a low internal resistance on discharge. In this connection I find that the .6 mm. perforated ebonite and 2 mm. wood separation ribbed one side (standardised in November last) appreciably increases the internal resistance at high discharge rates as demonstrated by the lower P.D. As you are aware, our former practice was to assemble R.R. 11 batteries with .4 mm. perforated ebonite and 2.5 mm. wood separation. When this matter of increasing the thickness of the ebonite was being discussed I expressed the opinion that .4 mm. was sufficiently thick and if it did wear thin in places as observed in your intensive Laboratory tests, the wood separation would continue to function satisfactorily. On enquiry at our Repair Depot I find that RR.11 batteries are never faulty by reason of failure of the separation and most of the ebonite separators are used again in the reconditioned cells. Our experiments have also shown that wood separators ribbed on both sides give a better performance at high discharge rates than separators only ribbed one side. The enclosed curves indicate that the best performance is given with .4 mm. ebonite and wood separators ribbed both sides. The Exide performance was obtained on a loan battery which has had a fair amount of service; I am obtaining a new Exide which may show better results. Contd. | ||