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. Claude Johnson regarding battery capacity and generator performance issues.
| Identifier | ExFiles\Box 48\3\ Scan027 | |
| Date | 7th October 1920 | |
| Oy3 - C71020 Oct. 7, 1920 Mr. Claude Johnson - 3 Our only doubt about this battery is whether the capacity is great enough. We are informed that the S.A.E. standard for a car of our capacity is an 90 ampere hour battery, and it may be that in spite of the less current consumption of our starting system the battery may give trouble this winter. X.30140 X.3878 We have numerous cases on imported cars where the car is brought back to the Service Station within a few weeks of delivery with the battery run down, but this is not the fault of the battery so much as the generator which does not cut in at an early enough speed. In practice we find that it cuts in about 15 or 16 miles an hour when cold and 18 or 20 when hot, and in practice with neglect of the belt it very often does not cut in when hot until 23 miles an hour. The average gear driven American generator cuts in between 8 and 11 miles per hour, and for American traffic conditions something like this is required. It is for this reason that we so strongly recommended the Bijur machine which cuts in earlier and gives a great rush of current to a discharged battery. We did not previously send Mr. Clarke a model of the Exide battery because we understood that it was practically identical with the new type of Chloride. Very truly yours, ROLLS-ROYCE OF AMERICA, Inc. Per M. {Mr Moon / Mr Moore} Olley MO/G | ||