Temperature and Specific Gravity On Car Battery
IMPACT OF TEMPERATURE On Car Battery
As a chemical device, lead-acid batteries do not store electricity rather they store chemicals capable of producing electricity, and so it is affected by temperature. All chemical changes are assisted by an increase in temperature and retarded by a temperature reduction.
The ability of a fully charged, serviceable battery to give the high current required by the starter motor is reduced by approximately 40% at freezing point (0oC) and by as much as 60% at -18oC when compared with the summer day performance at 27oC.
Also, cold weather makes engines harder to turn, calling for more battery current. This is why a battery that has performed without problems for a year or two usually starts to give trouble during the winter months.
THE IMPACT OF SPECIFIC GRAVITY On Car Battery
The amount of acid in the electrolyte is directly proportional to the state of charge of the battery. It can be measured if a sample of the electrolyte is in effect, weighed and its specific gravity is determined.
That can be achieved using a hydrometer which is a standard instrument for the measuring of density and specific gravity by comparing the weight i.e. density of a sample of an electrolyte with an equal volume of water.
The hydrometer consists of a glass tube with a rubber bulb at one end and a thin rubber tube at the other.
Inside the glass tube, there is a float that is calibrated from 1,100 to 1,300. When the rubber tube of the hydrometer is inserted into the battery cell below the surface of the electrolyte, a sample can be taken by pressing and releasing the rubber bulb.
The float sinks in the sample, and the specific gravity can be read from the point where the float breaks the surface of the electrolyte. Do not use a hydrometer within an hour of topping up because it will show a wrong reading.
