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 inquiring about the differences and proposed alterations to P & R batteries, focusing on charging resistance.
| Identifier | ExFiles\Box 54\1\ Scan080 | |
| Date | 12th January 1926 | |
| x4617 P EFCS/T. 12th January, 1926. Mr. K.{Mr Kilner} Preston, Messrs. Peto & Radford, Dagenham Dock, Romford, Essex. Dear Mr. Preston, Re Standard P & R Batteries for RR. Cars. We gathered from Mr Minchin recently that the very latest batteries which we are receiving already differ slightly from the original standard 40/50 batteries to our specification in a way which gives them less charging resistance. This point arose because you queried whether our table of figures dated 3.12.25 referred in the case of the P & R battery to one of the very latest. We said we did not know but would make sure by obtaining one of the very latest. This we have since done and have confirmed that the charging resistance is slightly, though not a great deal, less than the other one, e.g. our average charging P.D. per cell was about 2.75 on the latest as against 2.88 on that other, the charging amperes being down in approximately the same proportion. What we would like to know is - what exactly is the difference between these later cells and the earlier ones. Further, we should be interested to know the exact still further alterations which you are proposing to make to bring down the charging resistance still more until we get it down to the 2.69 of the Exide. The actual current in each of the two cases quoted of the latest P & R and Exide is 11.05 amperes. I suppose we may take it for granted that in the case of three P & R cells which we have recently obtained | ||