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 ampere-hour efficiency and density following a visit from Mr. Preston of Peto & Radford Co.
| Identifier | ExFiles\Box 38\5\ Scan197 | |
| Date | 2nd February 1922 | |
| X3398 2.2.22. x664 x3398 RE VISIT OF MR. PRESTON OF THE PETO & RADFORD CO. ON FEBRUARY 1st. 1922. --- Ampere-hour efficiency of a battery. Mr. Preston informed us that the ampere-hour efficiency of a battery when discharged at a 10 hour rate was about 90%, and the watt hour efficiency about 60% at normal working temperatures. This is a much higher value for ampere-hour efficiency than we obtained, our experiments being carried out for a high rate efficiency test. Densities of a battery on first charge. Mr. Preston informed us that the density of any battery on first charge cannot possibly fall below the initial acid density, providing that there is no water already in the battery to dilute the acid. A battery built up with damp separators is, in Mr. Preston's opinion, bad, as if such a battery is kept in stock for any length of time i.e. about 6 months or more, the plates hydrolise and lead hydrate is formed on the plates in the following manner :- PbSO4 + 2H2O <=> Pb(OH)2 + H2SO4. This action is reversible and goes on until a stable point is arrived at. This hydrate will cause the plates to buckle and short when on charge. The reason for the drop in the Chloride densities on first charge is probably due to water in the separators before the battery is first filled. The reason for increase of density when a battery is on its first charge is that the negative plates already contain some sulphate due to the fact that they have | ||