Comparing the performance of Peto & Radford batteries against competitors like Exide.
| Identifier | ExFiles\Box 38\5\ Scan124 | |
| Date | 25th August 1921 | |
| W/S. {Derby Works / Sales} EFC {E. Fowler Clarke - Electrical Engineer} 1/T25.8.21. To PN. {Mr Northey} from EFC. {E. Fowler Clarke - Electrical Engineer} c. R. {Sir Henry Royce} c. CJ. X.3398 - PETO & RADFORD BATTERIES. I have your PN {Mr Northey} 1/DN24.8.21. I must confess to having used the terminal "electrical efficiency" in perhaps a rather loose way, but I think I had in mind at the time more particularly the ampere-hour discharge capacity in relation to the weight of the complete battery. I certainly did not mean to use the term "electrical efficiency" in the sense of output divided by input, as this quantity does not concern us in this class of work. On our tests of earlier P & R batteries we experienced low rate discharge ampere-hour capacities and ampere-hour capacity weight efficiencies distinctly less than for C.A.V., Lucas and Exide batteries, but more on a par with some of the - in our opinion less good batteries, e.g. Fuller, early Tudor, Premier, etc. In the case of the third P & R battery received, i.e. the one you have at present on your car, we could not, do what we would with the battery, get it into a condition in which it would give more than 50 ampere-hours on the 10 hour rate, though its rated ampere-hour capacity was 60. Exide batteries on the other hand consistently gave equal or considerably more than their rated capacity, and doubly more in proportion to their weight, consequently. On the last P & R battery received of the high rate discharge type, we did succeed in obtaining the full rated capacity on the 10 hour rate. This battery is at present on the demonstration car. The internal resistance of all the batteries has seemed quite O.K., so that on the high rate discharge tests, each battery has started off giving a good current (though a given resistance). Excepting the case of the last one received (the high rate discharge type) the high rate discharge was not maintained so well as that of Exides. This point, however, does not seem to affect matters in practice materially. Contd. | ||
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).