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).
Continuation sheet discussing battery conditions, charging, and potential issues in new cars.
| Identifier | ExFiles\Box 54\2\ Scan228 | |
| Date | 24th May 1928 guessed | |
| Continuation No.1. When a Battery has been overcharged and is in a very poor condition or the plates are not covered by the correct Acid density specified by the Makers the pointer would not remain stationary after a load equivalent to a low discharge rate is connected across it. The pointer would gradually decline to the discharge position showing whatever condition a Battery may be in the amount of charge is always indicated under actual load conditions over a scale area. Any inflated voltage caused through Back E.M.F. sulphation, separators etc, immediately disappears when a load equivalent to a 10 hour rate is connected across it. From our tests the calibrations vary accord-ing to the Make of Battery. The Hydrometer will only give a true indication of charge when the acid is new and of the same density as specified on the Battery. On an old one it is possible to obtain the correct charged density of acid but the Battery would not contain the full stated capacity. When a Battery has been subjected to a heavy discharge the Instrument would immediately show a drop and then recover slightly in a very short time. This is due to the excessive discharge taken momentarily from the Battery, but if after a short time when the Battery has settled the testing load equivalent to a 10 hour rate is again put across the Battery it will indicate definitely how much charge has been taken from the Battery, and from our observations under actual charge conditions it takes very little time to put back the used charge. This of course depends upon the amount of charge consumed by pressing the Starter Switch and the rate of charge that the dynamo is gen-erating. The owner is able to put exactly the amount of charge in the Battery that has been used previously. We are confident that the damage to Batteries when used on a new car is done during the first 500-1000 miles. In the first place the Battery is fully charged, the owner is not instructed and has nothing to tell him when the Battery is fully charged. In the Instruction Book one is advised after the first 500 miles to have the brushes of the generator cleaned to remove all Carbon Dust. Owing to the Brushes being run into the Commutator of Dynamo, this gives an in-creased charge. Practically no new car owner has this attended to and consequently instead of the Dynamo | ||