Instruments and Controls Identification button is used to select the engine operating speed. See Chapter 7 for complete instructions. Battery Boost Push Button and Optional Battery Isolator System Ether Start Push Button, Optional A battery isolator system has two or three regular batteries to turn the starter motor, and one or two gel cell batteries to provide power for cab and sleeper accessories when the engine is off. The system uses an isolator relay, which is normally open. The relay isolates the engine-starting batteries while the engine is not running, so that the engine can still be started even if the gel cell battery has been used to the point of complete discharge.
For cold weather starting, the vehicle may be equipped with one of several manual-control, ether start systems. To start the engine in cold weather, push the ether button ( Fig. 2.7 ), then start the en- gine. See the engine operating instructions in Chap- ter 7 for additional information. When all four batteries have a charge, the engine can be started in the normal manner, by turning the ignition key to the "Start" position and pressing the starter push button. 1 2 To start the engine when the gel cell battery is drained, press and hold the BATT BOOST push but- ton ( Fig. 2.6 ) while pressing the starter push button.
This will temporarily close the isolator relay, and con- nect the engine-starting batteries to the ignition switch for engine starting. 01/18/95 f600648a 1. Ether Start Push Button 2. Battery Boost Push Button Fig. 2.7, Ether Start and Battery Boost Controls, Optional Low Voltage Disconnect, Optional The isolator relay is closed only while the engine is running or the BATT BOOST push button is de- pressed. With the engine running, all four batteries are connected in parallel, allowing the alternator to charge them all, in addition to supplying power for all vehicle loads.
The optional Sure Power Low Voltage Disconnect (LVD) system monitors battery power when accesso- ries are being used when the engine is shut down. The system automatically turns off cab and sleeper accessories when voltage drops to 12.3 volts to en- sure that there is enough battery power to start the vehicle. An alarm sounds for one minute before ac- cessories are turned off. If no action is taken within that minute, the LVD module will shut off power to predetermined cab and sleeper circuits, and illumi- nate an LED indicator on the LVD module, located inside the baggage compartment.
These circuits will remain off until the LVD measures 13.0 volts applied to the system, which can be done by starting the en- gine. After the engine is started, the system will reset. When the engine is not running, the gel cell provides all of the vehicle’s electrical needs except for turning the starter motor. The gel cell is longer-lived and cheaper to use than a standard wet cell, but it can take a charge only within an extremely narrow range—13.8 to 14.1 volts. At 14 volts, a gel cell has a very high charge accep- tance rate.
Because a truck charging system oper- ates at approximately 14 volts, under normal condi- tions a gel cell will never need to be recharged with an external charger. CAUTION All vehicles equipped with LVD should have a sticker on the dash indicating the presence of the system. Another sticker is located inside of the baggage com- partment, along with the LVD module. Do not attempt to charge a gel cell with a stan- dard battery charger. All standard battery charg- ers supply at least 16 volts to the battery. This will damage the gel cell. IMPORTANT: To recharge a gel cell, see an au- thorized Freightliner dealer or the instructions in 2.6