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).
Dynamo output curves and premature battery failures, particularly Exide batteries, due to over-charging.
| Identifier | ExFiles\Box 54\1\ Scan049 | |
| Date | 24th November 1925 guessed | |
| -2- Contd. to you, and I am quite prepared to reduce the outputs of the dynamos on the chassis, so long as I do not reduce them below these curves. But I cannot do this, owing to the known variations which occur from chassis to chassis, until I am sure that in making the reduction we shall not be reducing some of the chassis outputs below these curves. I am endeavouring to get from our Test Dept. an analysis of outputs as observed by them and to what extent they are affected by whether the chassis has an Exide or a P & R battery. I cannot believe that the shapes of these curves do not meet the two extremes in which our chassis may be used in a better way than a curve like the old Lucas curve, which starts late and then maintains a high output. That brings me to a consideration of your two statements :- (1) "We have had a good many batteries back, both of our make and Exide, and the condition of all of them is always the same, namely the paste coming out through over-charging and bringing the battery to an end." (2) "We get lots of Exide batteries back here off Rolls Royce cars. Owners come to us to buy a P & R battery as replacement thinking, perhaps, that the Exide has not lasted as long as it ought to have done, and they will try the other make and I have no doubt that Exide get just the same with people replacing our batteries with an Exide. We always open up these Exide batteries and have always found them done to death with over-charging." We should like to know how it is that you get Exide batteries, unless these batteries have given a normal life and the customer prefers to have a P & R battery the next time, and just leaves it with you to be scrapped. Our official arrangement is that cases of premature failure should be brought jointly to the notice of ourselves and the maker of the battery. Consequently it is rather disconcerting from our point of view to hear that you have "a good many batteries back" and also that you have "lots of Exide batteries back". But at the same time that it is disconcerting in this way, it also emphasizes the necessity for the change we have made in our present output curve as compared with the Lucas output curve, because one can scarcely suppose that any of these batteries of which you speak can, at the present stage, have [Handwritten in left margin:] + at least in the Instruction Book, we technically ask a customer to do this. | ||