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).
Comparison table of electrical characteristics for Ballast and Primary coil components from Remy and Delco.
| Identifier | ExFiles\Box 52\3\ Scan311 | |
| Date | 4th March 1920 guessed | |
| -2- BALLAST REMY K2. REMY 6. DELCO. Approx. resistance (ohms) cold. .610 .40 .37 Approx. resistance (ohms) (warm) .690 .43 .425 (When carrying current of same heating value as working current at 900 R.P.M. of timer and with platinum gaps set as below under contact breaker). Approx. R.M.S. working curr- ent coil at 900 R.P.M. (amperes) 2.38 1.50 1.60 Approx. average working current (D.C. value) (amps). 1.76 1.3 1.35 PRIMARY & BALLAST. Approx. resistance (ohms) (Ballast cold) .845 1.11 .90 Ditto (ballast warm) .925 1.14 .955 Approx. time constant under working conditions (sec) (ballast warm) .00325 .0066 .0049 Final current at 6 volts assuming working conditions (amperes) 6.49 5.26 6.29 Ratio ballast resistance / primary coil resistance 3.94 1.6 1.8 Contd. | ||