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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).
Performance issues and testing results for a two-rate dynamo charge scheme.

Identifier  ExFiles\Box 163\6\  img112
Date  31th December 1930
  
S/W
X6016
X.8780
To EFC. from Sg.{Arthur F. Sidgreaves - MD}
X.6016
re Dynamo - Two Rate Charge Scheme.
Sg{Arthur F. Sidgreaves - MD}21/E31.12.30
Copy to R.{Sir Henry Royce} Wor.{Arthur Wormald - General Works Manager} E.{Mr Elliott - Chief Engineer}
By.{R.W. Bailey - Chief Engineer} Hs.{Lord Ernest Hives - Chair} BN.{W.O. Bentley / Mr Barrington}

Referring to R2/M23.12.30 I should be very much interested to know how you account for the dynamo on 18-EX cutting in at 13 m.p.h. and charging constantly at 10 amps at slow road speeds if, as I assume, it is one of the new two rate charge dynamos such as was fitted to 58-GN.

In the last paragraph of R's memo. he suggests that the reports regarding results from the machine fitted to my car were incorrect but it was because I was anxious that there should be no misunderstanding about these results that you came specially to London to see them for yourself.

The dynamo as originally fitted up did not cut in until approximately 25 m.p.h. and then at a very low rate of charge.

With the lower resistance it cut in at 17 and gave

5 amps. @ 20
10 " " 25
14 " " 30

After three weeks' running results showed that even with the car doing a certain amount of work outside London it was unable to keep the battery adequately charged and we have now had to remove the resistance altogether.

I hope that whilst E.{Mr Elliott - Chief Engineer} is at Derby it will be possible to come to some definite conclusions as very soon production chassis will be coming through with these half charge dynamos on and it is most important that they should go out to the customers correct.

Sg.{Arthur F. Sidgreaves - MD}
  
  


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