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).
Usefulness of a battery charge indicator instrument compared to a green lamp system.
| Identifier | ExFiles\Box 54\2\ Scan238 | |
| Date | 23th July 1928 guessed | |
| -2- It does, however, appear that by arranging the sensitiveness of the instrument to be not quite so great, it can be made to be quite a useful indicator when actually applied to an electrical system. It is a question of making a suitable compromise in the relation of the indication to the existing voltage of the system in the varying circumstances. The instrument is supposed to be set for one of our standard Phantom batteries, and it is on such a battery that it has been tried. The instrument resistance is of the order of 1200 ohms so that when left on circuit, as intended, the drain from the battery is about 10 ma. We are still of our previous opinion that the indications of this instrument are of less value than those given by our green lamp system which can be set to a nicety to tell when to switch off the charge, which we consider is all that is really required. knowing the amount existing in the battery, itxis does not enable one to replace the defficiency any quicker. You will I think agree that all it is necessary to know is whether the battery may be considered to have received a full charge. EFC. {E. Fowler Clarke - Electrical Engineer} Letter returned for EX/Cgh. {W Clough} ✓ instrument to Roy. {Sir Henry Royce} | ||