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).
Differences between 48 and 60 watt bulbs in relation to the dynamo's output and battery charging.
| Identifier | ExFiles\Box 166\4\ img087 | |
| Date | 7th January 1931 | |
| X6089. PN.{Mr Northey}4/PH.7.1.31. EFC. ✓ Copy E.{Mr Elliott - Chief Engineer} Dy.{F R Danby} WOr.{Arthur Wormald - General Works Manager} Sg.{Arthur F. Sidgreaves - MD} X.6004 EFC1/AD/6.1.31. X.6089 [STAMP: RECEIVED 8 JAN 1931] Would you remind me please what there is in the 48 coil medium output dynamo which enables cutting in earlier; are there more turns? The point made at the end of your memo as to the relative desirability of the 48 watt bulbs or 60 watt bulbs is quite worth consideration. It is, of course, most unfortunate, that the difference in PD with a fully charged battery - a.{Mr Adams} when it is being charged, b. when it is just discharging, is so great. It would appear that in the case of our using the 60 watt bulb when giving a good light they would be mostly running at a too high voltage for long lighting. PN.{Mr Northey} PH | ||