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).
Battery conditions and experiments with sulphating and over-charging when using voltage control for dynamo output.
| Identifier | ExFiles\Box 164\3\ img089 | |
| Date | 15th December 1937 | |
| Rm{William Robotham - Chief Engineer}/RC.{R. Childs} 6021 BY.12/G.15.12.37. BATTERY CONDITIONS WHEN USING VOLTAGE CONTROL TO DYNAMO OUTPUT. Referring to Mr. Minchin's letter on the above subject, circulated under cover of Rm.{William Robotham - Chief Engineer}10/R.6.12.37. it will be remembered that I pointed out the danger of sulphating under voltage control of dynamo output, if the control was not set to give a reasonable charge under the minimum charge conditions when the battery was fairly well up. As the result of my statement Hs.{Lord Ernest Hives - Chair} referred the matter back to Electrical Department to ensure this aspect of the matter being fully considered and the control set to meet it. It was pointed out that during the six years I lived at Matlock my house was lit by a small automatic plant; for the first two years I ignored the automatic vibrator control, starting and stopping the dynamo personally, with the result that my battery output remained good but the plates suffered from overcharging, as I well "gassed" the plates on charge before shutting down the engine. I explained to Fowler Clark what I was doing, and mentioned the fact that the plates were suffering, he said it was the result of over-charging and said it would be better to run on the auto control set to show fair "gassing". I did this with the result that the battery capacity in six months almost vanished and the plates were too badly sulphated to be recovered, and this in spite of the fact that I set the cutout higher and higher, but carried on with the experiment to see what it resulted in. This information was put before Mr. West, and was emphatically raised by myself at our Conferences, but was assured it could not occur under our settings and running conditions; it is evident that in Mr. Minchin's case the settings were too low. As a further experiment I replaced my batteries and made a fresh start, still using the auto control, but this time watching the plates carefully and checking the battery capacity by running down on a known lamp load, | ||