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 to Mr. G.R.N. Minchin discussing battery charging rates, peak outputs and enclosed performance curves.
| Identifier | ExFiles\Box 54\1\ Scan048 | |
| Date | 24th November 1925 | |
| EFC2/T. X4617P 24th November, 1925. Mr. G.R.N. Minchin, 50, Grosvenor Gardens, London, S.W.1. X4617P XE780 Dear Mr. Minchin, Yours of yesterday's date. I think it is rather an exaggeration for you to suggest that because the normal charging rate of the battery on continuous charge should not exceed 8 amperes, that our peak output should not exceed this figure. For one thing, usually when the charge is on, the battery ignition is also on. I think I am right in saying that it is generally considered that there is no harm in charging batteries at a considerably higher rate, so long as they are not nearly fully charged, when the gasing does the damage. If the normal continuous charging rate of the battery is 8 amperes, I do not think a peak output of 12 amps, minus B.I. current, falling to 6 amps minus B.I. current at 55 m.p.h., (in accordance with our issued curve) will be at all too high. I enclose two blanks, one for 40/50 and one for 20 HP, containing only a dotted curve of specified output for the warmed up condition. We have a number of these blanks which we use for plotting on experimental curves. The inked-in figures are the approximate m.p.h. chassis speed. These curves were specified a considerable time ago and we have always aimed at making the dynamo output in the warmed up condition just top these curves, the curves purport-ing to represent minimum requirements. As already explained, it is true that our outputs in chassis, at any rate in some cases, considerably exceed these curves, and for reasons which I have already explained Contd | ||