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 discussing adjustments to dynamo output and potential causes for excessive current.
| Identifier | ExFiles\Box 51\1\ Scan186 | |
| Date | 19th July 1923 guessed | |
| Contd. -2- the output is too large for satisfactory running of the machine, and that in a number of cases the outputs have increased over the settings given by this specification. In view of this we are willing to concede to two-thirds of your request, i.e. to reduce the peak of the curve by 1 ampere, and we are altering and reissuing our specification of production test accordingly, hoping at the same time by reducing the set (production test) output this amount, to overcome the tendency to subsequently increase the output, owing perhaps to development of poor commutation due to too large current density. You will understand that we expect that this reduction of 1 ampere in the specification will make on the average a bigger difference than 1 ampere on the final result on the chassis, and hope to more nearly meet your demand in this way than would seem possible in actual reduction. We think that the cases you have had under your own observation, one of which was mentioned in your first letter, may perhaps have been a case where the output has increased after leaving our production test. Another reason for not conceding to your whole request is to give a little weight to our own opinion that the amount of charging a battery will get on the peak is not a serious proportion of the whole time, so we trust you will be able to agree to our meeting you to this extent. Another possible reason for apparent excessive output, though this would hardly be a likely reason if the whole electrical system on chassis 42-G3 referred to in your letter were under your own observation, might be the low level of electrolyte in the battery, because as you will appreciate, the moment the dynamo is allowed to work at a higher voltage than indicated by our curve in the column 'Operating Voltage', the ampere output will also be increased. Then again, at the moment at which the output was under observation, it is possible that the engine and dynamo were not up to the maximum temperature and we do not think the increased output for the relatively short period of running would ever be sufficient to injure the battery. It is extremely unlikely that on the engine being started, the battery would be in a fully charged condition, even though the starter were not used, there always being a certain amount of leakage during standing, which would first have to be replaced. Warming up Contd. | ||