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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).
Report page discussing the reversibility of lead accumulators, temperature effects on batteries, and comparisons with nickel-iron batteries.

Identifier  ExFiles\Box 38\5\  Scan198
Date  2nd February 1922 guessed
  
-2- Contd.

been originally assembled in a partially discharged condition.
On charge this sulphate is driven from the plates into the
electrolyte, a consequent rise of density resulting.

Reversibility of a lead accumulator.

We informed Mr. Preston of our experiment of reversing
a cell, i.e. charging it the wrong way round, and the result
was that we obtained as much capacity one way or the other.
He says that this is quite in order and a cell can be reversed
in this way and an equal ampere-hour capacity obtained. He
pointed out that to reverse a cell and come back to the
original condition would be a far more difficult matter, as
to do this the negative plates would have to be taken out,
washed and dried, before the reversal could be effected.

Temperature effect.

Mr. Preston laid great stress upon the effect of temperature
upon the ampere-hour and watt-hour capacity of a battery.
He thinks a temperature should be specified for all battery
tests carried out with a view to comparison.

He also pointed out to us that the efficiency of the
nickel iron battery is very low as compared with that of the
lead acid accumulator, this also varying greatly with the
temperature of the electrolyte. He pointed out to us that
P & R batteries do not come up to their full capacity until
about the tenth charge and discharge, this being due to the
hardness of the plates which goes to produce longevity of
the battery.

His theory of the frothing of the celluloid cell is
that it is due to camphoric acid being librated by the
  
  


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