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ELECTRICAL SYSTEM—Battery
THE BATTERY
Lucas GTW7A. 12v. 38 amp. hr. at 10 hr. rating.
About once every fortnight (more frequently in hot climates), top up each cell with
distilled water to bring the acid solution (electrolyte) just level with the top of the
separators. Do not use a naked light when examining the condition of the cells and on no
account use tap water when topping up.
Keep the terminals clean and well covered with petroleum jelly. If they are corroded,
scrape them clean, assemble and cover with petroleum jelly. Wipe away all dirt and
moisture from the top of the battery, and make sure that the connections are clean.
THE DYNAMO
The dynamo is of the compensated voltage control type and operates in conjunction with
the regulator unit which is housed alongside the cut-out in the control box.
The regulator unit ensures that the dynamo charges the battery at the rate best suited to its
condition. It automatically provides a large charging current for a discharged battery and a
low trickle charge for a battery in a fully charged state.
When the engine is at rest, or running slowly, the dynamo does not develop sufficient
current to charge the battery, and under these circumstances, the battery would discharge
itself through the dynamo if the cut-out were not fitted. The cut-out is operated by the
dynamo voltage, and when, due to increasing speed, the dynamo develops sufficient
voltage to actuate the cut-out, the points make contact and so allow current to flow from
the dynamo to the battery. In this system, current cannot flow in the reverse direction. The
cut-out requires no attention, it is correctly adjusted by the manufacturers and the sealed
unit must not be tampered with.
The brush gear and commutator on the dynamo will not normally require any attention.
After 50,000 miles (80,000 km.) however, it is advisable to have the unit serviced at a
Lucas depot.
Belt Tightness
See that the belt is sufficiently tight to drive the dynamo. It can be adjusted by slackening
the securing nuts and swinging the dynamo in the desired direction. Re-tighten the nuts
whilst holding the dynamo in the adjusted position. Don't over-tighten the belt as this
would put an undue load on the dynamo and the water pump bearings. The correct tension
is achieved when the belt can be pressed inwards about ¾ " on the longest run, i.e., from
the water pump pulley to the crank pulley.
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