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).
Car accumulator overcharging and potential methods for automatic control.
| Identifier | ExFiles\Box 59\1\ Scan120 | |
| Date | 1st March 1927 | |
| S/W. To EFC. Copy to R.{Sir Henry Royce} BJ. CWB. Hs.{Lord Ernest Hives - Chair} By.{R.W. Bailey - Chief Engineer} [Handwritten]: X4008 PN{Mr Northey}2/EH.1.3.27. CAR ACCUMULATORS - OVERCHARGING, ETC. AUTOMATIC CONTROL. [Handwritten]: X4008 [crossed out] [Handwritten]: X4009 [Handwritten in right margin, vertically]: over peroxidising the positive plates has Referring to your EFC1/T26.2.27., and R1/M15.2.27., my own feeling has always been, as you are doubtless aware, that we should supply on our instrument board some reasonably good indication as to the state of charge of the battery, in order that undue rises of voltage need not take place, which cause trouble-some conditions for lighting and, worse still, the effect of lowering the level of the acid and, incidentally, make any electrical operative devices of the windscreen wiper type unsatisfactory by reason of the large differences in speed. Probably, from the point of view of hand control, the ideal method would be to bring up a wire from each cell to a multiple volt-meter switch on the dash-board, in order that the P.D. of each cell can be observed, but obviously one does not want more wires and more switches in evidence if it can be avoided. The tests made experimentally in connection with your electrical magnetic switch for reducing the rate of dynamo charge are very interesting, and probably I should prefer to have some such device on my own car every time. But I feel doubtful as to the wisdom of adding to the already complicated nature of our electrical equipment a mechanism which, in the event of it failing to function for any small cause, would never be capable of being put right again other than by one of our own Depots. Also, so far you have still certain features to modify and get right before you can feel fully satisfied as to its reliability. In the absence of any automatic control, a volt-meter on the instrument board should be of considerable assistance as an indication of when charge should or should not take place. The point to decide in this case is whether such instrument should give a reading across the whole battery or merely one of the cells. I think one could take it that the chance of being misled would be greater by taking the reading for the six cells than by taking the reading of one cell only, and, in any case, the battery would, as usual, have to have reasonable inspection and attention. [Handwritten annotation]: well known [Handwritten]: X4010 The meter referred to by R.{Sir Henry Royce}, fitted to 7-EX, is probably continued... | ||