Battery Charger

An engine mounted alternator to charge the batteries during operation is an available option. Standby gensets require a solid state battery charger that is connected to utility power so the battery is charged continuously while the genset is not running. The battery charger should be connected to the emergency circuit. The batteries on prime power gensets are charged by the engine mounted alternator, if equipped.

Harmonic wave forms from solid state battery charges and belt driven alternators can cause the electronic governor on the engine to act erratically. To avoid this, the output of the battery charger or the belt driven alternator must be connected directly to the battery or to the battery terminals on the starter. Make control connections to the genset control using a conduit with a flexible section at the genset to avoid damage due to genset vibrations.

Battery Cables

The wire size (wire gauge) of the cables connecting the starter to the batteries must be large enough to ensure the resistance of the cranking circuit is less than the “Maximum Allowable Resistance of the Cranking Circuit” as shown on the Engine–Generator Set Data Sheet. The total cranking circuit resistance includes the resistance of the cables from the starting motor to the battery and the resistance of all relays, solenoids, switches, and connections. The resistance of various sizes of cables is shown in Figure 2-19. For purposes of calculating cranking circuit resistance to select cable size, the resistance of each connection can be taken as .00001 ohms and the resistance of each relay, solenoid, and switch can be taken as .0002 ohms. Figure 2-19 illustrates an example of a typical cranking circuit resistance calculation.

Figure 2-19 Typical Battery Cable Calculations

MN2408

General Information 2-21

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Baldor GLC125, GLC35, GLC80, GLC50 manual Battery Charger, Battery Cables