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).
Battery charging characteristics, comparing Exide and P & R cells and proposing a specification change.
| Identifier | WestWitteringFiles\N\2October1925-December1925\ Scan218 | |
| Date | 30th November 1925 | |
| EFC1/T30.11.25. -7- Contd. current is not quite so high as is reached a little later on, indicating that the battery actually has a higher resistance during these first few moments. It is an important thing for batteries which have to operate with so-called inherently controlled dynamos, working on a characteristic in which rise of volts and amperes go together, that the internal charging resistance of the battery be kept down as much as possible, otherwise the volts and amperes of the system are put up, and the overcharging effect is still further aggravated. It appears that the Exide cells give least effect in this direction and the P & R cells the most, as extreme cases have been observed, when, with the same charging current, the terminal P.D's on the Exide cells fully charged and gasing were only 2.5, whereas those on the P & R's were 3.0, and in other cases we have observed 2.6 and 2.9 respectively. The matter is being suitably taken up and probably a clause will be added to the battery specification to limit the terminal P.D. on charge at 12 amperes to some suitable figure. Contd. | ||