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).
The examination and testing of a 40/50 Exide battery from chassis 25-MC for Lord Rochdale.
| Identifier | ExFiles\Box 70\3\ scan0071 | |
| Date | 15th December 1926 | |
| X8783B To Hm{Capt. W. Hallam - Head Repairs}/FHA. from EFC. EFC3/T15.12.26. 40/50 EXIDE BATTERY EX CHASSIS 25-MC. LORD ROCHDALE. With reference to Hm{Capt. W. Hallam - Head Repairs}/FHA1/WW3.12.26, we have re-examined and tested this battery. The battery as received by us required considerable topping up, the acid being approximately 1" below the tops of the plates. Cells Nos. 1, 5 & 6, reckoned from the negative end, were low in voltage and shewed negative weakness on the cadmium test. This is indicative of the battery having stood for a considerable time either in a practically discharged condition or with low electrolyte. In other words, the battery has not been fairly treated in respect of charging and level. Batteries which are fairly treated do not shew negative weakness, but always positive, at the end of low rate discharge. When fully charged we found the specific gravity to be correct. On low rate discharge it gave 40 ampere-hours. This is too low; and the same three cells shewed negative weakness at the end of the discharge. Again charged and given a high rate discharge, some improvement was noticed due to the thorough charging, but the same three cells shewed negative weakness and their voltage dropped very quickly, due to the negative elements in these cells being at fault. Negative weakness on high rate discharge generally occurs even in a good battery, but does not come on so readily as in the case of these three cells. You will see that there is sufficient evidence of unfair treatment of the battery which may have been due to the unsatisfactory exposure of the negative plates to the atmosphere by the level being low. Two essential rules about battery treatment are as follows, and as given by us very definitely in the Instruction Book:- (1) It is most important that the battery should not be allowed to stand with its terminal voltage below 10.8. (i.e. below 1.8 volts each cell) as this will shorten its life. (2) It is of even greater importance to keep all plates always will covered with electrolyte. We could probably put this battery in better condition by special treatment (low density charging) if you so desire, or we can give you instructions as to how to carry out this process in your own Dept. In any case Contd. | ||