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).
Letter detailing the advantages and applications of a patented relay device for controlling battery charging.
| Identifier | ExFiles\Box 59\1\ Scan360 | |
| Date | 30th April 1930 guessed | |
| (3) One other great advantage of my device is that as well as switching the charging rate from "Full Charge" to "Half Charge" or "Off", in the former case where it is used to switch on to "Half Charge" it protects the accumulators from too heavy a charge when they are "Well up" and "Cold". As you know, when a cell is "cold" it will not stand as heavy a charge as when it has been on charge for some time and become "warmed up" on account of the voltage rising more when they are cold. In the case of a "well up" cell this voltage rise is often sufficient to cause the same effect as over charging the cell, but my device protects them from this by switching them on to "Half Charge" which would be the best for them in the case of a long run, and in the case of a short one, as soon as the engine was slowed up or stopped and started again, the relay would allow "Full Charge" till the voltage rose to the set value again. The great advantage of my relay is that it is practically immune to road shocks and engine vibration and will only work at the set voltage, neither above nor below. If it was used to control accumulators for house lighting, etc., it could be made very easily to operate both for stopping and starting the charging unit when the voltage of the battery rose above a set value and when it fell below another value owing to a load being put on partially discharged cells. If you are interested in my device I would be pleased to hear from you. I can let you see the model I have made working very satisfactorily on my own car if you wish. I would say that the device is provisionally patented. Yours truly, Eric H.{Arthur M. Hanbury - Head Complaints} Taylor | ||