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 Peto & Radford detailing the results of a life test on a 6HZDS Dagenite battery for a Bentley engine.
| Identifier | ExFiles\Box 164\2\ img057 | |
| Date | 7th November 1940 | |
| Rm{William Robotham - Chief Engineer}/EC.4/ET. 7th November, 1940. Messrs. Peto & Radford, DAGENHAM DOCK, Essex. Attention of Mr. Clapham. Dear Sirs, With regard to our recent conversation regarding lighter batteries, we estimate that the requisite starting current for the engine in question will be approximately 160 amperes at a temperature of 8°F.{Mr Friese} We are enclosing details of a life test taken on your 6HZDS9 type battery, which was recently carried out in our laboratory. The battery was tested against another well known make, and the results proved yours to be superior. TEST RESULTS: Type - 6HZDS - DAGENITE. Capacity - 49 A.H. Weight - 38 lb. 13 oz. (without lid{A. J. Lidsey} or securing bolts) STARTING ABILITY: In this test the battery was discharged for 5 seconds at 280 amperes, which current, approximately, would be required to turn the Bentley engine in very cold weather (8°F). The terminal voltage at the end of 5 seconds is the measure of the battery's ability to start the engine. It is also an indication of the magnitude of the internal resistance. Normal Temperature 8°F 9.02 volts 7.32 volts STARTING CAPACITY: The object of this test was to ascertain the capacity of the battery, or to what extent it could repeatedly start the engine before failing. This was measured by the number of minutes it could maintain a current of 100 amperes or more, when discharged on a certain constant resistance. The current, at the commencement of discharge, i.e. the maximum current, is also an indication in respect of the internal resistance. Maximum Current Time over 100 Amps. 107.3 7 minutes | ||