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 discussing battery separators, internal resistance, dynamo charging peaks, and output curves for 20 HP and 40/50 models.
| Identifier | ExFiles\Box 54\1\ Scan056 | |
| Date | 27th November 1925 | |
| PETO & RADFORD. CONTINUATION 3. E.{Mr Elliott - Chief Engineer} Fowler Clark Esq., 27th November 1925. With regard to the position of the separators, we are making some tests at the Works to see if our voltage is so much higher than the Exide and when we have got some figures I think Mr. Preston and I will come and see you and look into yours. I certainly thought that in our 40/50 we had ribs on each side of the wood separator, but I have enquired and find you are correct in what you say. Mr. Preston says that an alteration in the manufacture of our plates came in, in the batteries which were manufactured during September this year and since, which was done with a view to lowering the internal resistance, and he asks whether you have taken tests on any of the very latest batteries received or whether all the ones you refer to are some months old. Your suggestion of changing my dynamo is interesting, although it is a bit drastic to have the peak at only 8 amperes. I do not think I suggested quite as drastic a'change as this when I said it was overcharged at the peak because I realise that it must be over-charged to a certain extent then. I will be interested to try the dynamo if you would like it and it would be very interesting to see if it would keep the battery up to the mark. I am rather doubtful whether it would (at an 8 amp. peak) but am quite willing to try the experiment. Why dont you try one as well and get two opinions? You say that my proposal for the 40/50 would amount to reducing the output curve proportionately on the vertical scale from 11 to 8. I am sorry if I gave you this impression and I agree that if you did you probably would have a big outcry. I think if it was reduced one ampere all over from the photostat curve you sent of the 40/50 output that it would be about right and 1 1/2 to 2 amperes reduction on the 20 h.p., but better than this is to have a much lower rate and to have your present output (or a little more) when the head lamps are on. The 20 H.P. battery, both ours and Exide, is 50 ampere hours; normal charging current 5 amperes. It is charged at the peak at 10 amperes. The 40/50 battery of ours and Exide | ||