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).
Issues with the 20/25 HP dynamo output, cutting-in speed, and half-charge scheme.
| Identifier | ExFiles\Box 60\4\ Scan152 | |
| Date | 22th April 1932 | |
| AH 22/4/32 BY.{R.W. Bailey - Chief Engineer} Hs{Lord Ernest Hives - Chair}/Wst. WST x6099. EP{G. Eric Platford - Chief Quality Engineer}3/H22.4.32. re. 20/25 HP. DYNAMO OUTPUT.HALF-CHARGE SCHEME. With further reference to Mr7/T21.4.32. and Sg{Arthur F. Sidgreaves - MD}10/E19.4.32. I do not agree that there has been any discrepancy in regard to the characteristic of the above on production cars, as compared with Experimental Department specification. I was able to demonstrate to our people in London on Thursday on two 25-HP. cars tested . in one case cutting in actually took place at 16 m.p.h. and in the other at 17 m.p.h. I fear that some confusion has been caused by the description of the cutting in condition. It is true that no definite "charge" takes place until 19 or 20 m.p.h. is reached due to the current taken by the battery ignition absorbing the output from the dynamo between 17 and 20 m.p.h. I was able to explain this to Sg.{Arthur F. Sidgreaves - MD} and Pn.{Mr Northey} who I met at Brooklands track on Thursday. We were not satisfied with the output and "cutting in" condition on the first production cars of this type, and discussing it with the Experimental Dept. it was realised that to obtain an earlier cutting in speed was a very difficult point, and that the specification now carried out was one which had been tested out on the last 10,000 miles test and approved by Sales Dept. It is,however, considered that something should be done to improve this condition, as it is pointed out that one can drive one of these cars continually round London for the whole day without any charge going into the batteries. Again, it must be realised that there is the other extreme, and which is now giving trouble, i.e. that when the side lamps only are on, the increased output is such that the voltage to the lamp is too high,causing burnt out filaments, and although it is pointed out that higher voltage lamps should be used,these are not generally available, and if this point is pressed it will be necessary to arrange for the standard makes of these lamps to have such high voltage lamps always available. EP.{G. Eric Platford - Chief Quality Engineer} | ||