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).
Technical bulletin detailing the condition and maintenance of accumulator (battery) elements.
| Identifier | ExFiles\Box 44\5\ Scan024 | |
| Date | 2nd December 1927 guessed | |
| 1A. ACCUMULATOR ELEMENT CONDITION. Prolonged experience with accumulators of various types has enabled us to arrive at certain conclusions leading to a rather more practical statement than is usually given of what we think an accumulator user should know. The tendency of the positive elements of a cell subject to average treatment is to remain robust electrically but become weak mechanically. The active constituent of this element being a saturated oxide, it does not readily suffer from exposure to the air. Continued overcharging super-peroxidises the plate grids and renders them weak mechanically, and liable to burst, and even to fall to pieces, though still remaining in good active condition electrically. Positive plates which will fall to pieces on dismantling a cell may be quite good electrically, except for the fact of reduced grid conductance. The tendency of the negative elements of a cell subject to average treatment is to remain strong mechanically but become weak electrically. The active element is finely divided metallic lead, which upon exposure to the air, will readily oxidise. It is very important that negative plates be not exposed to the air, particularly when in a fully charged active condition. In a new battery the negative plates do not require more charging than the positive, i.e. they gas profusely as soon as the positives. In an old battery in which (1) The level of the electrolyte has never been allowed to fall below the plates, (2) Freshening charges have been given at intervals not exceeding one month, and (3) The P.D. of the cells has never been allowed to fall below 1.8 volts on discharge or the density below 1150, the same still applies, i.e. the negative and positive plates gas profusely with the same amount of charging and the limit to the life (with slowly diminishing capacity) in this case, apart from faulty separation, is reached when, with the normal amount of charging repeatedly carried out, there has resulted sufficient deposition from the plates to pile up the space underneath the plates and cause a short circuit. Contd. | ||