Lesson 2/Learning Event 2
Be careful not to splash electrolyte onto you or the equipment.
Point the tester toward a bright light source. When you look through the eyepiece lens, you will
see a rectangle with two calibrated scales - battery charge readings on the left scale, antifreeze
readings on the right.
The electrolyte sample will divide the rectangle with an area of light and an area of shadow. You
read the scale where they meet.
A full charge is 1.225 specific gravity for tropical electrolyte and 1.280 specific gravity for temperate
If below 1.180 specific gravity for tropical electrolyte and 1.225 specific gravity for temperate
electrolyte, replace the battery with a fully charged one if you cannot charge it in the field.
Battery capacity is greatly reduced by low temperatures because the electrolyte thickens and is less
active. In addition, the engine is harder to crank so the starter motor requires more current. To
perform satisfactorily in cold weather, the battery must be kept in peak condition. So when the
temperature drops, you will have to keep a closer watch on the battery.
In cold weather do not let the specific gravity drop below 1.250 if you expect the vehicles to start.
When the temperature is colder than -20F, the vehicles should be stored inside where it is warm,
if possible. If they must be parked outside, the batteries should be heated during long periods of
standby; otherwise, they will not take a charge or have enough capacity for normal use.
The electrolyte is also subject to freezing; the exact freezing point depends on the specific gravity.
In a fully charged battery, the electrolyte will freeze at -90F. As the specific gravity drops, the
freezing point rises. The following table shows the freezing point for various specific gravities.