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).
Technical discussion on dynamo specifications and the problematic, inaccessible placement of accumulators on car chassis.
| Identifier | ExFiles\Box 46\3\ Scan291 | |
| Date | 23th August 1923 guessed | |
| -2- Contd. dynamo or higher speed of some other make of electrical equipment. The dynamo I suggest should be the bi-compound type, with a rated supply of 18 amperes at 12 volts under full load running condition, and should begin to generate, saye at 350 - 400 r.p.m. with the usual Compensator or cutout between the dynamo and accumulators, then, if the accumulator requires recharging, the dash meter should show 12 amperes, which should fall to 4 or 5 amperes, when the battery has been brought up to charge again. If the machine is bi-compound wound, this arrangement should ensure automatically an increase of current as soon as the headlights are switched on. For the time being, what can be suggested to alter the arrangement on the cars, with us already ? Another matter, which is of extreme importance to your Firm, is for them to arrange a suitable place for the accumulator and not leave it for the coachbuilders to place them in inaccessible positions and I cite the instance of the last two cars supplied to us, viz:- Closed Cabriolet by Messrs. Barker & Hooper. Open touring by Messrs. Hooper & Co. The accumulator casings are slung on a cross tube under the back floorboards by U shaped brackets and it is an impossible task to remove this arrangement under one hour on the road and the help of a second man is also required. The accumulator casing has a sliding opening at one end, but is useless; for on trying to slide the accumulator out, it strikes the back axle casing and cannot be removed unless the whole is taken down. I am afraid the Home people do not realise the importance of the necessity to enable an easy inspection and removal of this important adjunct, in fact, it would be far better to secure the spare wheels under the chassis with chains and locks (as tyres do not give the trouble now-a-days), and place the accumulators where the spare wheels are. I mean to infer that they are the most important accessory as far as India is concerned and must be easily got at. I draw your attention to the method employed in the Minerva cars, which have the accumulator partly inside the valances and pull out on to the running board with ease. | ||