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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).
Letter from an accumulator manufacturer discussing battery discharge rates, capacity, and specifications.

Identifier  ExFiles\Box 38\5\  Scan055
Date  14th May 1919
  
X 3398

Manufacturers of P. & R.{Sir Henry Royce} Accumulators. Established 1889.
Victoria & Greville Works, Ashtead, Surrey

THE NEW PETO & RADFORD ACCUMULATOR CO LTD
Electrical Engineers

MANAGING DIRECTORS
WILLIAM PETO M.I.E.E.
G.{Mr Griffiths - Chief Accountant / Mr Gnapp} R.{Sir Henry Royce} N. MINCHIN M.A.

12 HEDDON STREET
REGENT STREET
LONDON W·1
TELEPHONE REGENT 2576
TELEGRAMS "CONCENTRATION REG. LONDON"

REF. M/C.145
14th May. 1919.

Messrs. Rolls-Royce Ltd.,
Nightingale Road,
DERBY.

Dear Sirs,

For the attention of Mr. Fowler Clarke.

In your last letter you referred to the fact that we had discharged our battery at 3 amps for 20 hours, whereas you were more interested in the 10 hour rate.

The 20 hour rate is the S.M.M.T. definition that most of these car accumulator capacities are based on.

We discharged the battery at 6 amperes and it ran for 10.3 hours before the cells were down to 1.8 volts.

We are now discharging it at 150 amperes to see for how long it will maintain this, and when we have got this fugure we will send you the actual curves of these various discharges, or copies of them.

In your specification you do not say down to what voltage you expect to work with the 150 amperes.

The aircraft specifications during the war varied, specifying 9, 8 and 6 volts fora 6 cell battery.

We should be glad to hear your views on the matter.

We should like to explain that with all our standard plates we have these curves etc., but this is a new plate designed in the light of war experience and we have to obtain the figures you ask for as we go along. The 60 ampere hour capacity we gave at the start was estimated.

Yours faithfully,
THE NEW PETO & RADFORD ACCUMULATOR CO. LTD.

G.R.N.Minchin
MANAGING DIRECTOR.
  
  


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