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 charging issues on the 20/25 HP model and proposed solutions, including fitting a larger dynamo and modifying the switchbox.
| Identifier | ExFiles\Box 163\6\ img177 | |
| Date | 29th June 1932 | |
| WST X6016. PN.{Mr Northey}1/WT29.6.32. Saves from PN.{Mr Northey} Copy to E.{Mr Elliott - Chief Engineer} Cop. by Cax Hs{Lord Ernest Hives - Chair}/Wst. Battery Charging 20/25 H.P. Because it is fully realised the margin of dynamo capacity output on this model does not exist, we are hoping that it will be possible to fit the larger dynamo of P.II on both types of car as early as possible. As you are aware this will entail certain modifications to the aluminium crankcase castings on the 25 H.P. Consequently, in order to avoid scrap it is necessary to consider by what means we can best make our charging and lighting scheme on the 25 H.P. immediately better to deal as far as possible with the following considerations which have to be kept in view. (a) The battery must be kept in a condition of charge during the winter at a time when the greatest amount of discharge will be required from it by most owners. (b) The battery must not be allowed to get into a state of habitual overcharge in the winter by those owners who use their cars chiefly about towns and never use their headlights. The battery must be safeguarded as far as possible from being overcharged, also from the point of view of damage to lamp filaments and overheating of dynamo. Both these contingencies are possible if the battery is over-charged, and its pressure is allowed to rise much over 14 volts. (c) It should be possible to maintain the battery in a reasonable condition of charge during the summer period without any lights on. Hs{Lord Ernest Hives - Chair}/Wst. is at the moment plotting out the simplest way of modifying our switchbox in order that the three-charge scheme referred to in E.5/HP.11.6.32 can be put before R.{Sir Henry Royce} in its clearest form, but this comparatively simple modification has been so far considered only in connection with the P.II dynamo, and therefore is not likely to become available until the 25 H.P. crankcases, referred to above, are used up. I suggested to-day to Wst. when here that this proposed modified switchbox should be meanwhile very useful in connection with our existing smaller | ||