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Ammeter Readings
The ammeter indicates the amount of current passing into or out of the battery. Supposing that the dynamo is generating 7 amperes and that some of the side and tail lamps are in use, taking, together with the ignition coil, 3 amperes, then 4 amperes are left for charging the battery. This is the reading given on the ammeter.
With compensated voltage control equipment it must be remembered when noting ammeter readings that normally during daytime running, when the battery is in good condition, the dynamo gives only a trickle charge so that the charge, reading will seldom be more than 3 or 4 amperes.A discharge reading may lie given immediately after switching on the headlamps. This usually happens after a long run when the voltage of the battery is high. After a short time the battery voltage will fall and the regulator will respond, causing the dynamo output to balance the load.When starting from cold the charging current will.rise until it reaches a steady maximum at a speed of, say, 20 miles per hour, after which it will remain fairly high for about 10 minutes, then fall to a steady charge which is most suitable for the particular condition of the battery.

Checking Ammeter Readings
To check the accuracy of the ammeter readings, connect an ammeter in series with it and compare the readings of the two instruments.It must lie remembered that the ammeters used on motor vehicles are not precision instruments, as they are designed to withstand the excessive vibration that is possible under had road conditions. These instruments are, however, sufficiently accurate for checking the normal operation of the equipment.

Ammeter Fails to Indicate
Usually caused by the ammeter being overloaded due to a short circuit in the wiring between the ammeter and the cut-out and fuse unit. Examine the wiring for evidence of damage and fit replacement ammeter.
In the event of an open circuit in the ammeter indicated by the lamps and accessories not operating when switched on, the ammeter can be "shorted" by joining its two terminals by means of a length of wire until a replacement can he fitted.

Switch Units
Occasionally, say when the vehicle is taken down for a general overhaul, the terminals of the switch should be examined and, if necessary, tightened. Remove any stray strands of wire which may cause a short circuit.

Switchboard. (C.A.V. Type No. 47)
This switchboard being only 3.5” (89 mm.) face-plate diameter, is a compact unit for flush fitting into a dashboard or panel. If sufficient slack is allowed in the cables the complete board can he withdrawn from the front of the dashboard by removing the clamp and the two nuts securing it in position at the back.
The board is fitted with a main rotarv switch for the control of the tail, side and tail, head side and tail lamps, together will an additional turn switch fur ignition control. Either magneto or coil may be used, but it is not suitable for dual ignition. Dynamo charging is indicatcd by a red pilot light fitted to the right of the ignition switch.

Copyright Sjoerd van de Wal- Krebs 23-06-2017