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 discussing the Auto Charge Control Switch, its potential testing, and a comparison of battery charging systems.
| Identifier | ExFiles\Box 43\1\ Scan033 | |
| Date | 28th February 1928 | |
| CY7/R.2.28.28. X 3988 February 28th, 1928. Mr. E.F. Clark, Rolls-Royce Ltd., Derby, England. Dear Mr. Clark Re Auto Charge Control Switch. X.3988. X.4008 Many thanks for your note EFC3/T9.2.28 in which you described the windings adopted for the six volt auto charge switch. We shall be most interested in testing this device at Springfield. The whole question of the necessity of reducing the charging rate to the battery is a thing to which you seem to give more importance in England than we should consider necessary. The Exide 3-XX-21-1 battery which we use, does not appear to come to any harm through charging almost continuously at rates between 10 and 15 amperes. The generator obtains its peak so early and falls off so much after the peak that even after it is set at its maximum charging rate by adjustment of the third brush, the actual charge flowing into the battery is not more than 10 or 12 amps. at speeds above 35 miles an hour. The only disadvantage of this charging rate that we know of is a rather frequent necessity for adding distilled water, but since we carry the battery in a metal case attached to the outside of the frame, it is very accessible and convenient for adding water. As far as I can see, the chief advantage of the auto charge switch is that it will not be necessary to reset the third brush for winter and summer conditions. Very truly yours, M.Olley | ||