His trouble was that he did most of his running at night and as he carefully observed the speed laws, consequently the generator did not generate very much extra current and the battery was being recharged at a very low rate and being discharged at a rather high rate. In other words, he was chopping off both ends—burning both ends of his candle. He was using an excessive amount of current and generating less than usual because of running at night, starting often, and running slow to observe the speed laws. Up to a certain point, the amount of current which goes into the battery is increased in proportion to the speed of the car.
Generators are constructed so that they will deliver a normal charge to the battery for normal running; they must not be constructed so they will send out excessive current, or they will overcharge the battery, and that is harmful. The sun sets much earlier in winter and the cool weather makes it necessary to use the starter more. In warm weather one little kick will start the car off; in cold weather it takes often from half a minute to a minute.
Most engines now are equipped with carburetor check and priming devices to facilitate starting when the engine is cold, but even with these more current is consumed in starting the engine than when it is warm.
Then, too, the storage battery drops off in efficiency as the temperature is lowered and will not deliver so much current on a full charge as at a higher temperature. This comes at a time when there is a greater call on the battery, and where a battery fails under such circumstances, it is wise to get an occasional charge to help out the generator.
It is becoming the practice to take all current for lights, ignition, and other purposes direct from the battery, using a generator to recharge it. Inside of a year at the most the bottom of the battery will become filled with a sediment from the plates. This causes an internal short circuit and the battery will discharge itself inside instead of outside. At least once a year a battery should be taken apart and the sediment be cleaned out.
Some generators are constructed so that they can be adjusted to deliver more current on demand; that is, there is one adjustment for summer and one for winter running. Wherever it is possible to do this it should be done. Otherwise, when a battery loses voltage, it can be taken off the car and be charged. It need not be necessary to leave it for a twenty-hour charging period; if taken soon enough it can be charged in six to ten hours, or, when the car is laid up over night. Two nights would be enough at any rate.
As a matter of fact, in self-starter practice, everything is done to the storage battery that formerly was included in the list of battery “don’ts.” On account of the exceptional demands of self-starters, batteries have been improved so that they stand this to some extent; but the improvement has not kept pace with the extra demand put upon the battery.
Some of the old “don’ts” are:
You should not charge the battery at a high rate when completely discharged.
It should not be charged at a high rate when almost fully charged.