Battery (endurance test)
If a cold vehicle does not want to start in the morning, it makes sense to have the battery tested. Above, an old tester is displayed. A problem with it was that its ballast resistors regularly became dangerously hot when
switched on. But the principle of a load test can be well explained using the old tester. Three sizes of batteries are distinguished. The larger the battery, the more resistances are added, connected in parallel, by
turning the knurled-head screws. You have to press both noses from above solidly on the (disconnected) battery Pole and read the achieved voltage from the display.
|12.24 V correspond to a charge of roughly 50%|
Today such a load test is integrated in almost every workshop battery charger. It takes for a short time a big current from the as much as possible fully charged battery (> 12.66 V) and checks how strongly the tension
drops. Actually, for the inquiry of the test current for low temperatures the battery must have a certain negative temperature, but most often already the test in the warm workshop will do. If the voltage drop is too large,
e.g. to 8 volts, the battery should be renewed. The test is also possible with a blocked starter motor, but already after few seconds it might become too hot. And then you have even more problems, except for the broken
battery. In addition, this test is not possible if your vehicle features a control unit that supervises the starting.
It is nice if the workshop regards the load test as free service, because you should not spend a lot of money, e.g., for a 7 - 8 year-old battery. Maybe it is worthwhile to exchange the battery if you suspect its
malfunctioning, looking at the prices of an average (petrol-driven car) battery, especially as it is recycled anyway.