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 on battery charging procedures, polarity testing, and completion of charge.
| Identifier | ExFiles\Box 26\2\ Scan367 | |
| Date | 14th June 1920 guessed | |
| -5- Unless one has some familiarity with matters of this kind it is preferable to call in an electrician). If the lamp lights to full brilliancy on one main and not on the other, the main on which it does not light is the one which is earthed, and the battery should be connected to it. If the lamp does not light on either main, or it glows dimly on both mains, neither of the mains is earthed, and it is preferable in these circumstances to connect the battery to the negative main. The polarity of the charging wires to the battery may be tested by dipping their ends in a glass of water to which a teaspoonful of salt has been added. In doing so it is assumed that a charging or limiting resistance, or lamp of "mains" voltage, is already in series so as to avoid trouble from short circuiting (see Fig.3). Bubbles of gas will form on the negative wire. It is necessary to be quite certain that charging current is flowing into the battery in the correct charging direction. Limit the current to the proper rate (about 7 amperes) by varying the lamps or other resistances in series with the battery. Incandescent lamps or radiator elements are convenient for this purpose. (see Fig.2) When charging as above, the watts taken by the lamps or elements connected in parallel (as shown in the diagram), when added together, should be about 700 watts on 100 volt mains, 1400 watts on 200 volt mains. It is, of course, only the current taken by the lamp and not the brightness of the filaments that determines their suitability for use as resistances. (19) Completion of Charge. The charge should be continued until conditions detailed in paragraph (20) are fully complied with. Note paragraph (21) re temperature permissible. Avoid overcharging the battery. {From this point onwards, present paragraphs (22) (23) (24) (25) and (26) will be exactly as at present, their numbers being (20) to (24) respectively. The last paragraph, (27) at present, we suggest should now become as follows :-} | ||