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 detailing battery failure analysis, including issues with wooden separators and ebonite rings.
| Identifier | WestWitteringFiles\D\April1920\ Scan12 | |
| Date | 6th August 1919 | |
| -2- Contd. has exercised sufficient force to enable the wooden separator beyond to be compressed sufficiently to allow the plates to make contact one with another. We may say that we have had one case of this type of failure in the case of one of our standard batteries and that this case was pointed out to your Mr. Greenhalgh during his list visit here, only as we had otherwise damaged this particular block of plates, we decided not to write you about this until another case occurred. We have, however, exercised the greatest care in taking out the two present blocks of plates from their cases not to disturb the plates and separators in any way, and we are now keeping these until you have an opportunity of inspecting these. It would appear that very great care is necessary in the fitting of the wooden separators before placing the block of plates in its box. Although the wood is no doubt an excellent material for separators in many ways, nevertheless it is not so robust that buckling of the plates will not in some instances actually cause contact to be made by the plates squeezing through the wood until they come into contact. Another point we would like to bring to your notice is that in two of the six cells, the screwed ebonite ring at the bottom of the filler hole had come out and so allowed the ring closing and unclosing the vent holes in the sides of the filler channel to drop down as well on to the plates. It would appear necessary to have some means of locking the first mentioned ebonite ring in position. We carefully noted the amount of sediment, and this amount we considered quite reasonable compared with the amount of running the battery had done. As regards the other four cells which were still alright, we took a carefully low rate discharge from these and found the capacity (55 ampere-hours) to be at least equal, if not better than the capacity given before being placed on the car. Would you care for us to despatch to you the two blocks of plates mentioned, or could you arrange for your Engineer to pay us a visit with a view to inspecting these, as we think that it is a fault which may occur on standard batteries, but at the same time may be preventable in the manufacture. Contd. | ||