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).
Charging and discharging cycle for a 6HZD11.S battery for a life test.
| Identifier | ExFiles\Box 164\3\ img195 | |
| Date | 5th July 1938 | |
| -3- Rm {William Robotham - Chief Engineer} /RC. {R. Childs} 15/JH. 5th July. 1938. Taking the 6HZD11.S. battery with a 10 hour rate capacity of 61 amp. hours, it would be more convenient to discharge the battery during the night, and recharge during the day. The time available for charging during the day is 9 hours. If normal charging current is 7 amperes (6.1 amps. + 10%) then input on charge will be 63 amp. hours. We estimate that at the 7 hour discharge rate the capacity will be 92.4% of that corresponding to the 10 hour rate, that is, the output will be approx. 56.3 amp. hours. Allowing 10% additional charge then the input on recharge must be about 62 amp. hours. We could thus carry out one cycle in 24 hours. The difficulty appears to lie in making and calibrating a suitable discharge resistance and automatic switch, the later to open the circuit when the volts have dropped to 10.8 during the night. Another point is that the battery would have to stand in a fully discharged condition for 7 or 8 hours before charging commenced. We think, on the whole, however, that this together with the intervening series of high rate discharge tests would constitute a simple and reasonable life test. Yours faithfully, FOR ROLLS-ROYCE LTD. | ||