Adjusting Generator Outputs
The repairman should be very slow in adjusting generator outputs. Most cases of insufficient or excessive charging current are due to the troubles enumerated in the foregoing paragraphs, and not due to incorrect adjustment of the regulating device. Before changing the adjustment of any generator, therefore, be sure that everything is in good condition. The third brush generator, for instance, will have an excessive output if the brushes are dirty, loose, or not well seated on the commutator. The use of a third brush which is too wide, for instance, will change the output considerably. A high resistance third brush will decrease the output, while a low resistance brush will increase the output. On the other hand, an increase in the resistance of the charging circuit will cause an increase in the output of a third brush generator, which is just the opposite to what is ordinarily expected. Such an increase in resistance may be due to loose or dirty connections, dirty cutout contact points, corroded battery terminals and so on. Remember also that the third brush generator sends a higher current into a fully charged battery than it sends into a discharged battery. It is, therefore, essential that a fully charged battery be on the car when the output of a third brush generator is adjusted.
There are two things which determine whether any change should be made in the charging rate on the car, viz: Driving, Conditions and the Season of the Year.
Driving Conditions. A car which makes short runs, with numerous stops, requires that the starting motor be used frequently. This tends to run the battery down very quickly. Moreover, such a car usually does not have its engine running long enough to give the generator an opportunity to keep the battery charged, and to accomplish this, the charging rate should be increased.
A car which is used mostly at night may need a higher charging rate, especially if short runs are made, and if the car stands at the curb with its lights burning. Long night runs will generally call for only a normal charging rate, since the long charging periods are offset by the continuous use of the lamps.
A car used on long daylight runs should generally have the charging rate reduced, because the battery is charged throughout such runs with no discharge into lamps or starting of motor to offset the continued charge. If the lamps are kept lighted during such runs, the normal charge rate will be satisfactory, because the lamp current will automatically reduce the current sent into the battery.
In the winter time, engines must be cranked for a longer time before they will start, the battery is less efficient than in warm weather, and lights are burning for a greater length of time than in summer. Such conditions require an increase in the charging rate, especially if the car is used on short runs. Oil long runs in the winter time, the normal charging rate will generally be satisfactory because the long charging period will offset the longer cranking period.
In the summer time, engines start more easily than in winter, and hence require less cranking. The lamps are used for only short periods and the battery is more efficient than in winter. A lower charging rate will, therefore, keep the battery charged. Long tours in the summer time are especially likely to result in overcharged, overheated batteries, and a reduced charging rate is called for.