Page 298 - 05. Subyek Teknik Mesin - Automobile Mechanical and Electrical Systems Automotive Technology Vehicle Maintenance and Repair (Vehicle Maintenance Repr Nv2) by Tom Denton

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Electrical systems 281

Figure 3.50 Flat posts

Figure 3.51 Correct polarity is important: red cables are used for the positive connection

There are two ways of charging batteries in the workshop; one is a slow or
Key fact
trickle charge and the other a fast charge. These require two different types of
charger. Most batteries can be fast charged, but this should only be carried out Smart Charger: A recent ‘plug play’
infrequently. If a high charge is used this can cause some deterioration of the development, this device will revive,
charge, condition and maintain
battery’s active materials.
lead-acid batteries. It determines
A slow charger or bench charger uses mains electricity. Inside is fi tted a a battery’s charge and then sets
transformer to reduce the voltage to 6, 12 or 24 V, to suit the battery or batteries the appropriate rate. Intended for
unsupervised use they are spark
on charge. Also fi tted is a rectifi er to change the a.c. volts of the mains supply
proof and reverse-polarity protected.
to the d.c. volts needed for charging batteries. The charger is connected to the
The clean voltage and current
battery terminals with the correct polarity ( Fig. 3.51 ). After setting the control supplied means they are safe to use
switches, the charger is then turned on at the main switch. on a battery, which is still connected
to the vehicle. The charger can
There are several different types of charger and these should be used in
be left attached to a battery for an
accordance with the manufacturers’ instructions. The recommended charge rate
indefi nite time without risk of damage.
for a battery is one-tenth of the ampere-hour capacity. A 40 Ah battery should be
charged at 4 A. If the ampere-hour capacity is not known, set the rate to one-
sixteenth of the reserve capacity. Where the charge current can be adjusted, this
facility should be used to set the rate.