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).
Instructions for the first charge of a battery, including a specific gravity conversion table and discharge/recharge procedures.
| Identifier | ExFiles\Box 26\2\ Scan090 | |
| Date | 6th August 1919 guessed | |
| -4- contd. During this first charge, watch density of acid in each cell, using a syringe hydrometer, and do not allow it to exceed 1.250. If it does, withdraw some acid and replace with distilled water. In order to facilitate the use of the hydrometer wgen determining the specific gravity of the electolyte we list below the principle readings which will be required:- Specific Gravity. Twaddle's Hydrometer Degrees. Baume Degrees. 1.035 7 5 1.175 35 22 1.200 40 24 1.225 45 27 1.250 50 29 1.835 167 66 The battery should now be allowed to discharge through resistances or lamps to 10.6 volts (current passing) at an ampere value of 1/10 of the rated ampere hour capacity (i.e. 5.5 amperes with a battery of 55 ampere-hours). Then recharge immediately at approximately the same rate as above discharge (or thereabouts) until all plates again gas freely (i.e. for about 15 hours). Now empty acid to waste and renew with acid of correct density (1.250) covering plates by 3/16". Continue charge until all plates again gas freely. | ||