Page 68 - Vauxhall 20-60 H.P. (R Type) Chassis Shop Manual

VAUXHALL 20-60 SHOP MANUAL

CHARGING PERIOD

SECTION It is difficult to lay down rigid instructions for the period at which the
356 battery should be charged, as the conditions under which cars are used
vary considerably, and obviously, the amount of charging the battery
will require is directly dependent on the number of starts made and the
extent to which the lamps are used. The following suggestions will serve
as a rough guide:—

1
1 With switch in ‘ / 2 C ’ position, charging rate will be sufficient to maintain
the battery during summer months when lights are infrequently used.
2 Always keep switch in ‘C’ position when lamps are in use.
3 If the car is used for long hours in the day time it is quite unnecessary
to keep the charging switch in the ‘C’ position as this will cause over-
charging of the battery and consequent reduction of acid level.

DYNAMO

SECTION Description — The function of the dynamo is to supply current for the
357 ignition, lighting and other electrical appliances, and to charge the battery.

The ordinary shunt wound dynamo increases its output as its speed
increases. To limit the current generated when the engine is running at
high speeds, the third brush principle of current regulation is employed.
Adjustment of the third brush position is explained in ( Section 359 ).

CHARGING CURRENT

SECTION To prevent the storage battery from discharging through the dynamo at
358 low speeds when the dynamo voltage is below that of the battery a cut-
out is introduced into the charging circuit which automatically breaks the
circuit between the dynamo and battery when the voltage drops below a
certain point.

When more than sufficient current is generated to supply the ignition and
other electrical appliances in use, the surplus flows to the battery and the
amount is indicated on the ‘charge’ side of the ammeter. This is the ‘charging
current’.

When the only current used is for ignition the charging current is the total current
generated less that used for ignition purposes (approximately 2 amperes). At
speeds below approximately ten miles per hour in top gear the cut out is open
and no current is generated.

At such times the ammeter should indicate a discharge of about 2 amperes
used for the ignition if no lights are on, and a larger discharge if the lights
are turned on. The cut out closes at approximately ten miles per hour in
top gear and at this point the dynamo begins to generate current. At a
speed of approximately twelve miles per hour the dynamo output should

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