How the Lay-electric Can Be Got
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it of Its Rut,
By A. W. Haigh,
A.M.I.Mech.E., A.M.I.A.E.
THE design of the pre-war battery-electric vehicle in this country leaves a lot to be desired. Little thought, in the majority of cases, seems to have been given to layout or weight saving, the general impression imparted being that standard petrol vehicles have been converted' by substituting electric motors, controllers and batteries for engine, clutch, gearbox, accelerator and petrol tank.
Manufacturers mulct entirely be blamed, for nearly every vehicle they produced was specially constructed to the prospective owner's requirements, .whilst, often, so little time was available between the placing of the order and the commencement of production that designers had no opportunity to give their products the thought necessary to turn out the best possible vehicle.
Compare the time allowed in a mass-production automobile drawing office for the design of one model, which varies Min six to 18 months, with that allowed for a battery-electric, which, to the writer's personal knowledge, is sometimes as short as three weeks, and some idea of the lack of thought, rather than concentrated study, which is put into it will be realized.
Bearing of Output on Cost
, So long as a prospective purchaser is allowed to dictate the design of his vehicle, the purchase pricer will remain abnormally high.. It is only through quantity production of a big number of standardized models that initial chassis cost can be reduced. For a large production programme the demand for eleetrics must be increased from the pre-war figure of approximately 1,000 a year to at least 20,000. Then, perhaps, their design would receive as much attention "-as that given to their mass-produced petrol-engined counterparts.
_ The applications of electric vehicles to local delivery w;ork are almost innumerable. Evidence can be produced to a show that practically all municipal utility vehicles and tradesmen's vans and lorries in nearly every town in the country could be run more economically on electricity than petrol; and after the war petrol will be almost unObtain able for same time. It follows, therefore, that petrol vehicles which can be replaced by electrics, and which are showing even now signs of deterioration through long usage and inadequate servicing, will be replaced by them if their price be reduced to a competitive level. .
When an operator has proved for himself that electric
traction really is more economical than petrol, instead of reading columns of figures in the Press which, he is told, establish the fact for him, he will automatically continue to purchase electrics even when petrol. can once mire be
bought as required. .
Assuming, then, that post-war? demands for electric vehicles will be sufficient to justify mass production, cbassis price will be competitive with that for petrol vans, but battery cost must still be borne. A recent statement in the Press, to the effectthat the Q electric-vehicle concern proposes to hire batteries, when It is in full production A24 . after the war, is an obvious solution to the problem.
Batteries are the main, if not the whole, argument against the electric vehicle. Their weight and bulk are a nuisance, whilst their inability"to lift the vehicle out of the localdelivery rut, through lack of powv after 30 miles or so, is exasperating. It is necessary to carry half a ton of batteries on a vehicle of gross weight 24 tons for -a range of 30 miles and a balancing speed of approximately 30 m.p.h. Of this
half ton, less than 20 per, cent. is taken up by. " active " material. the remainder being casipg, plate frames,. water and other essential items.
Battery manufacturers are, no doubt, endeavduring to increase the active-material , to total-batteryweight ratio and we may see revolutionary results after the war, but even if batteries can be produced at half their present weight the range will be only doubled.
Whilst a 60-mile range %%ill undoubtedly increase the sphere of application of the battery-electric, it will not ensure successful competition, in the long-distance delivery class, with the petrol vehicle. Until either fully charged batteries can be substituted fer exhausted units at wayside charging stations, • or a rapid charging system which does not affect capacity, efficiency and plates, can be devised, the battery-electric must remain just a local-delivery vehicle.
Charging time, at present, is eight hours. The aim .of electrical engineers should be to reduce this time to eight minutes or—even better—eight seconds; then electric motors would, quite definitely, he serious competitors to internal-combustion engines in the transport world.
• Charging Rate and Efficiency
Our, modern experts will probably condemn the idea of rapid charging, but they usually condemn all revolutionary ideas on principle. We know that, through rapid charging, active material is loosened in the plates, and capacity is greatly decreased, with a consequent drop in efficiency, but there is ‘a possibility that these, and the many other difficulties, can be overcome to some extent, at least.
When Edison decided to invent an alkaline battery, he paid no attention to the "can't be done" experts. He rolled up his sleeves arid spent 15 years in producing his nickel-iron unit. After 10 years he was sufficiently satisfied with it to start full-scale production, but there were a few complaints of batteries that refused to work. He immediately closed the works and spent another five years on improving the battery before he would again release it for public use. His biographer states that 50,000 combinations_ of materials were tried which produced little or no results before nickel hydrate and iron oxide were hit upon. It is the Edison spirit which will solve the problem of rapid charging!
The very nature of the chemical battery, however, is against ultra-rapid charging of the eight-minute or eight. second order. The eight-hour period will, without doubt, be greatly reduced, but, If the time cannot be reduced sufficiently for waysine. stops to be made while charging is done, a different type of battery from the chemical must be found.
At the present time it is futile to suggest that a condenser could be used to store a sufficient charge to run a vehicle, for even one which could provide a small fraction of the power required would be many times the size of the vehicle -itself. But It would also be futile to suggest that the future cannot produce a small edition of a condenser which would provide enough current, of which discharge could be controlled, which would not leak and which would retain the outstanding advantage of almost instantaneous charging.
A suggestion that a small condenser can be designed, which will store the same energy as a large one is a fair a2d
target for the old quips about quarts into pint pots, bdt the seemingly impossible has been achieved before now.
The General Motors concern in America has a notice posted on its walls to the effect that, according to all the rules of aero-dynamics and wind-tunnel findings, the ordinary bumble bee, because of its 'weight, bulk and inadequate wing span, cannot possibly fly, but the bee. "just ups and flies, anyway." The inference is obvious.
The ideal to be aimed at in the design of battery-electrics is the trolleybus without the trolley. In order to do away with the trolley the. overhead wiresmust be discarded, and in order to discard the Wires and ensure that the Vehicle range may be unrestricted, power must be transmitted in a -similar manner to . that used for our radio _programmes: Radiated power has . been the dream of .scientists for many years,. but few ..people realize that it is an accomplished fact in a
small • way. Demonstrations have been staged to audiences of both highly' technical men and ordinary folk, whereby small electric bulbs, equipped with antennae, have been • lighted, and fractional-horse-power motors have been provided with current by radiation. Whilst these achievements lre far from being practical, and farther still from being commercial, propositions, they -do show that radiated power is no longer a dream.
'When this Utopia arrives, the job of
• the electric-vehicle designer will be
simple Batteries will be. discarded and motors, instead of being kept to minimum dimensions, as is the case now, will be increased in size so that intermediate gearing between them and the road wheels will not be necessary. But, until then, batteries must still be housed and motor and transmission sizes kept down.
Weight reduction is not the complete „answer to good electric-vehicle design, the connections between battery, motor and controller must be given an equal proportion of attention. If every ounce of weight is being saved, then everj,r last fraction of battery capacity. must be used / and lbss of power in transmission must be brought down to the bare minimum.
Assuming that the batteries are carried in the normal pannier position and that the drive is taken through the rear wheels, the obvious way to prevent transmission losses is to use either wheel motors, with -electric balance between off and near sides, ot a Motor mounted directly on the axle with the. orthodox mechanical differential, the former being preferred if. as has been proved possible, motors
are employed which require no re-,(1 cLion in their drive. Electrical connections also would be reduced to minimum lengths by mounting the controller as near the motor or motors as possible and operating it by remote control from the cab; in this way, besides increasing available power, cable weight would be decreased. In view of .the heavy current that has to be required this is a by no means immaterial factor. .
" Many chassis layouts can be devised and many arguments put, forward to support their efficiency, Mit, no matter what the actual positions of units on the chassis, the rules Which must be adhered to ire those which ensure minimum chassis weight and maximum available power. . When these have been achieved the designer can congratulate himself 'on, a good job and wait tor Utopia with the knowledge that the best has been done with the materials that are available to him. '