Exide Farm lighting Batteries are made with sealed gla.s.s jars, open gla.s.s jars, and sealed rubber jars, each of which will be described.

Batteries with Sealed Gla.s.s Jars.

Two types with sealed gla.s.s jars are made, these being the Delco Light Type, and the Exide type.

1. Delco-Light Type. This type is shown in Fig. 294. The cell shown is a pilot cell, there being two of these in each battery as explained below.

These cells are made in two sizes, the KXG-7, 7 plate, 80 ampere hour cell, and the KXG-13, a 13 plate, 160 ampere hour cell. These cells are a.s.sembled into a 32 volt, 16 cell battery, or a 110 volt, 56 cell battery.

The plate groups are supported from the cover, the weight being carried by the wooden cover supports as shown in Fig. 294. The strap posts are threaded, and are clamped to the cover and supports by means of alloy nuts, just as is the case in Exide automobile batteries.

A hard rubber supporting rod or lock pin extending across the bottoms of the plates holds the separators in position and prevents the plates from flaring out at the bottom. A soft rubber b.u.mper fastened on each end of the rod acts as a cushion to prevent jar breakage in shipping.

The hard rubber cover overlaps the f.l.a.n.g.ed top of the jar, to which it is sealed with special compound.

Battery Gauges and Instruments for Testing.

Every set of Delco-Light batteries has either one or two cells equipped with a pilot ball. Such a cell is known as a PILOT CELL. Fig.

294.

Pilot Cells are used to indicate to the USER the approximate state of charge or discharge of the battery.

The pilot ball is a battery gauge which is UP or DOWN, depending upon the state of charge of the battery.

Very high temperature affects the operation of the pilot ball. This accounts for-the fact that occasionally a battery will be charged and the pilot ball will be at the bottom of the pocket. A few hours later, after the electrolyte has cooled, the pilot ball will rise to the top.

We urge that the user be made to feel that the pilot ball is an excellent gauge and a good signal to watch in connection with the care and operation of his Delco-Light plant and battery. (Further mention will be made of the pilot ball in connection with the subject of proper operation.)

It is necessary that the maximum specific gravity of pilot cells be as near 1.220 as possible. Any great variation higher or lower will affect the operation of the pilot b.a.l.l.s. Therefore, every effort should be made to adjust the maximum specific gravity of pilot cells to 1.220 when placed in service.

Batteries equipped with one pilot cell contain a white pilot ball which will be up when the specific gravity of the electrolyte is approximately 1.185. This ball will drop DOWN when the specific gravity falls a little below 1.185.

In other words, the pilot ball will float at a specific gravity of 1:185 or higher, and will sink at a specific gravity lower than 1.185.

Therefore, when the pilot ball is UP, the battery is more than half charged. When the pilot ball is DOWN, the battery is more than half discharged.

Batteries equipped with two pilot cells have one cell which contains a white ball and the other cell a white ball with a blue band.

The plain white ball will be UP when the specific gravity is approximately 1.175. The blue band ball will be UP when the specific gravity is approximately 1.205.

When both b.a.l.l.s are UP, the battery is charged. When DOWN, the battery is discharged. The blue band ball will drop soon after the battery starts on discharge, or, in other words, when the specific gravity falls below 1.205. The white ball will remain UP until the specific gravity falls below 1.175.

The Ampere-Hour Meter

The ampere-hour meter, Fig. 304, is an instrument for indicating to the user the state of charge of the battery at all times and serves to-stop the plant automatically so equipped, when the battery is charged. (Further mention will be made of the ampere hour meter on page 471.)

In order to check the speed of the ampere-hour meter, use the following rule: On charge, the armature disc should give 16 revolutions in 30 seconds, with a charging rate of 15 amperes; on discharge, the armature disc should give 20 revolutions in 30 seconds, with a discharging rate of 15 amperes.

[Fig. 304 Delco-Light Ampere-Hour Meter]

Hydrometers

The standard hydrometer for service men is known as the Type V-2B.

A special type hydrometer showing three colored bands in place of numbers has been designed for users.

The bands are red, green and black. When the hydrometer test shows the bottom of the red band in the electrolyte, the battery, whether in gla.s.s or rubber jar, is discharged. When the top of the green band is out of the electrolyte, the gla.s.s jar battery is charged. The top of the black band out of the electrolyte indicates the rubber jar battery is charged.

When and How to Charge Battery

Plants with Average Loads

Loads of legs than ten (10) amperes can be taken directly from the battery, until:

1. The large hand on the ampere-hour meter reaches 12, or

2. Both pilot b.a.l.l.s are down, or

3. Hydrometer test shows bottom of red band in the electrolyte.

If any or all of the three gauges listed above show the battery discharged, the plant should be started and operated continuously until the battery is charged, as indicated by:

1. Ampere-hour meter hand at FULL, or

2. Both pilot b.a.l.l.s UP, or

3. Hydrometer test shows top of FULL band out of electrolyte.

(NOTE: Any one or all of the above three items may indicate battery charged. Meter hand at FULL would necessitate both b.a.l.l.s UP. If both b.a.l.l.s are not up, set hand back and charge to bring them up; then set hand at FULL.)

Should the user be operating for two or three hours with a seven or eight-ampere load, it would be more efficient to run the plant to carry this load. This only applies for those cases where the battery is partly discharged.

Carry Heavy Loads Greater Than 10 Amperes.

If there is a constant load of 10 amperes or more, the plant should be started up when the heavy load comes on. When the heavy load is off, the plant may be stopped, but it would be entirely satisfactory to allow the plant to continue to run until "Charged," as indicated by: