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).
Laboratory tests determining the voltage of fully charged and discharged batteries.
| Identifier | ExFiles\Box 164\3\ img015 | |
| Date | 19th March 1937 | |
| To EP.{G. Eric Platford - Chief Quality Engineer} from Rm{William Robotham - Chief Engineer}/Wst. 6021 Rm{William Robotham - Chief Engineer}/Wst.1/AP.19.3.37. With regard to your enquiry as to how far a battery may be discharged, we carried out tests in the lab., obtaining the following results. The voltage in each case being taken across the terminals of the battery Ph.III. Standard Battery. Fully charged 10.55 volts. Fully discharged 7.3 volts. A.M.40.A.H. Battery. Fully charged. 9.4 volts. Fully discharged. 5.1 volts. The tests on these two batteries were carried out under the same conditions, namely, 200 amperes discharge. This is the maximum current taken to start a cold engine. It should be noted that the starter button should not be kept down for more than 10 seconds. Rm{William Robotham - Chief Engineer}/Wst. | ||