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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).
Solutions for improving the dynamo output on a 20/25HP model.

Identifier  ExFiles\Box 62\3\  scan0469
Date  5th December 1934
  
46037

Wor.{Arthur Wormald - General Works Manager} From Hs{Lord Ernest Hives - Chair}/Wst.
c. to By.{R.W. Bailey - Chief Engineer}

Hs{Lord Ernest Hives - Chair}/Wst.6/MA.5.12.34.

Re. 20/25HP. DYNAMO OUTPUT.

Referring to your Wor.{Arthur Wormald - General Works Manager}4/R.4.12.34., we agree that we cannot suggest to customers the use of a spare battery or even safely advise them to use a trickle charger.

On the other hand it is extremely difficult to satisfy all types of customers with regard to their dynamo output.

Regarding C's statement that the dynamo does not cut in until 19 M.P.H. we think this is an exaggeration as our figures show this to be 15 M.P.H., in the Winter charge position.

We suggest therefore for special conditions where the car is used extensively in London at night time, that the customer should be supplied with a resistance unit which will give him increased charge in the Winter charge position. We can supply By.{R.W. Bailey - Chief Engineer} with particulars of this in order that some resistances can be made up.

The only difficulty with this suggestion is that if the customer runs his car for any lengthy periods with this new resistance he might get trouble due to side lamps burning out. There is no royal road to success with this third brush dynamo scheme like there is with the constant voltage system, recently standardised on the 20/25.

Alternatively the customer might be provided with a switch to short circuit the resistance when running on Winter charge conditions in Town and thus secure full charge. This scheme however would only be successful when used intelligently and if used indiscriminately might result in dynamos overheating.

Hs{Lord Ernest Hives - Chair}/Wst.
  
  


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