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).
The physical and electrical properties of battery separators, comparing them to wooden alternatives.
| Identifier | WestWitteringFiles\U\May1930-July1930\ Scan143 | |
| Date | 1st July 1930 | |
| EFCL/ADS.7.30 contd. -3- (3) The speed of percolation of acid through these separators is extremely high, in fact, from 40,000 to 100,000 times (according to porosity) higher than the flow through a wooden separator. This enables the acid of a battery to be constantly mixed. (4) The separators can be made of absolutely uniform porosity giving a uniform current density throughout the whole surface of the electrodes, thereby minimising the tendency of the plates to buckle. (5) The separators are flexible and strong and comparatively incompressible; they absolutely prevent short-circuiting through the separator. They can also stand much higher temperatures than wood, in fact up to 140° to 150° Fahrenheit which is of great value for use in tropical countries or in batteries such as electric traction, when high discharges are required. (6) Once assembled the separators are practically indestructible. (7) The separators can be stored and exported dry and retain their electrical resistance and condition in these circumstances. Electrical Properties. (8) The separators being made with a high porosity give an extremely small resistance which is much less than that of treated wood separators. They also obtain their minimum electrical resistance within a few minutes of their being immersed in the electrolyte. Batteries with these separators can be exported dry-charged, a condition which is almost impossible with wooden separators. (9) By means of unequally subdividing the diaphragm by unequal ribs, automatic circulation is set up which increases the effective ampere hours of discharge at high rates. For this purpose the separators are exceptionally valuable for motor car starter batteries and electric traction batteries. | ||