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 comparison of P&R and Exide battery components including negative plates, separators, and cell covers.
| Identifier | ExFiles\Box 168b\3\ img022 | |
| Date | 2nd September 1929 guessed | |
| -2- P & R negatives. No. of plates 6 Active and whole surface same as positives. Thickness .130". The P & R plates have the apices of the grid bars facing inwards, whilst the Exide are the opposite. In my opinion the P & R is the best method of keying in the active material. The plates also have the advantage of being less wide, thus better allowing for the stretching of the positive plates which will facilitate removal of the plates and also save the bulging out of the case to such a great extent. Both types of plate have the same active area of 24 sq. in. though the P & R may lose a little of this with their type of grid. Separators. The wood separators in both cases are larger than the plates and reach up to the plate straps, and down to the bottom of the feet which is a good point. Both Exide and P & R are ribbed on both sides. Exide. The wood separators are .085" (2.15 mm.) thick, the flesh being .042" (1.07 mm.) thick. The ebonite separators are .019" (.48 mm.) thick, and perforated with circular holes .066" dia. P & R.{Sir Henry Royce} The wood separators are .096" (2.45 mm.) thick, the flesh being .038" (.96 mm.). The ebonite separators are .014" (.36 mm.) thick, and perforated with circular holes .055" dia. The Exide used to fit ebonite separators of a thinner type (about .4 mm.) but perforated with slots. The circular holes in the P & R ebonite separators are smaller than those in the Exide as will be seen by the above. Cell Covers. The Exide cover is of ebonite with a screw vent plug also of ebonite. A sealing joint for the terminal posts is provided by a soft rubber gasket washer on each post, over which is placed the cover and this being tightened down by a lead gland nut on a special four start thread. | ||