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).
Methodology for a special battery efficiency test under starter motor conditions.
| Identifier | WestWitteringFiles\H\January1922\ Scan45 | |
| Date | 31th January 1928 | |
| To E.{Mr Elliott - Chief Engineer} from EFC. c.c. CJ. & PN.{Mr Northey} c.c. Ry. & EP.{G. Eric Platford - Chief Quality Engineer} c.c. Rg.{Mr Rowledge} & Ds. c. Hw. ORIGINAL RE SPECIAL BATTERY TEST. <664 We think Mr. Royce might be interested in a special battery test we have carried out over a period of time to discover the efficiency of the battery under starter motor operating conditions, or put in another way, what number of ampere-minutes of current must be given to the battery after taking out so many ampere-minutes on a high rate starter motor discharge. For this purpose we started off with a fully charged standard battery of capacity about 50 ampere-hours, and proceeded as follows :- The battery was first allowed to discharge through our invariable high rate discharge resistance of .100 ohm for 2 minutes, and a curve plotted at the time of discharge, the amperes being in the neighbourhood of 100 but, of course, gradually falling. A graphical integration of this curve gave the number of ampere minutes discharge from the battery. The battery was then charged for half an hour at such a current (in the neighbourhood of 6 amperes) as would give the battery exactly this number of ampere-minutes. (The time of charge was fixed as being a simpler way than fixing the rate of charge, and using a corresponding time). Contd. | ||