COLD WEATHER CARE

ELECTRICAL

at a low rate until fully charged. Batteries may be safely

ALTERNATOR (Fig. 3)

slow-charged at a rate in amperes equal to 7% of the

battery's ampere-hour capacity. This is called the

A. GENERAL

"normal" charge rate. The battery is fully charged when

specific gravity readings taken at hourly intervals show

The major parts of the alternator are the stator

no increase during three consecutive readings.

assembly, the rotor assembly and the two end frame

assemblies.

2. A very low rate - not more than one-half the

normal charging rate - should be used for charging a

sulfated battery. In the case of badly sulfated batteries,

as much as 100 hours of charging time may be required

before the battery becomes fully charged.

Badly

sulfated batteries may require a continuous slow charge

for 48 hours or more before a rise in gravity reading

occurs. If the specific gravity reading of any cell fails to

reach 1.250 (corrected to 80 .) or if there is a variation

of more than 25 gravity points between cells after

thorough slow charging, replace the battery.

3. Although

the

slow-charge

method

recommended for charging all batteries, discharged

batteries in otherwise good condition may be given a

boost with a quick charger if time does not permit

complete slow charging. When using a quick charger, it

must be remembered that the battery is only receiving a

partial charge and that the battery electrolyte

temperature must not be allowed to exceed 130 . If

the battery heats up excessively, quick charging must

Figure 3.

be discontinued.

The stator assembly (Fig. 4) is made up of a laminated

D. COLD WEATHER CARE

iron frame and a stator or output winding which is wound

into slots of the frame.

A battery operated in an undercharged condition may

freeze during severe winter weather. The freezing point

The stator assembly is sandwiched between two

of the electrolyte varies with specific gravity. A fully

stationary end frames.

charged battery with 1.285 specific gravity corrected to

80 . will not freeze at minus 80 .

The rotor assembly contains a doughnut-shaped field

coil mounted between two iron segments with several

interlacing fingers which are called "poles". It is held

together by a press fit on the shaft. The rotor turns

inside the stator assembly.

The rotor shaft is supported by prelubricated bearings in

each end frame, a ball bearing in the drive end frame

and a roller bearing in the opposite end frame. (Fig. 5)

B-57