ch10_mbe4000

MBE 4000 APPLICATION AND INSTALLATION10 ELECTRICAL SYSTEM Section 10.1 10.2 ELECTRICAL SYSTEM DESCRIPTION ................................................. INSTALLATION GUIDELINES ................................................................. Page 10-2 10-3 All information subject to change without notice. 10-1 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION 1 ELECTRICAL SYSTEM DESCRIPTION The purpose of the electrical system is to provide the electrical energy required to start and run the engine. 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . The electrical system (see Figure 10-1) typically consists of the following components: Cranking motor and solenoid Battery charging alternator (Alternator) Voltage regulator (generally integral to the alternator) Storage battery(s) Ignition switch Figure 10-1 Engine Electrical System 10-2 All information subject to change without notice.ELECTRICAL SYSTEM 10. The wiring links the battery to the starter and the alternator to the battery.2 INSTALLATION GUIDELINES The engine electrical system with properly matched parts provides a balanced system which should meet all operating requirements. These batteries require frequent servicing especially adding water. The cranking motor converts electrical energy from the battery into mechanical energy. and are not recommended for engine starting. The alternator converts rotational energy from the engine to electrical energy. These batteries never need water.MBE 4000 APPLICATION AND INSTALLATION The battery stores electrical energy. Water must still be added periodically. Terminal posts do not tend to accumulate salt and corrosive deposits since there are no filler caps to leak acid fumes.1 BATTERY The battery is a device for storing electrical energy and converting chemical energy into electrical energy. 10-3 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . Maintenance-free Batteries Maintenance-free batteries use lead-calcium grid construction without antimony. This electrical output of the alternator is transferred to the battery where it is stored for later use. and cleaning salts and corrosive deposits from the terminal posts. so cable inspection and cleaning are infrequent. 10. Deep Cycle Batteries Deep cycle batteries are used for applications like electric drive carts. Salt and corrosive deposits must be cleaned from the terminal posts.2. 10. Four basic type of batteries are currently available: Filler cap batteries Semi-maintenance free batteries Maintenance-free batteries Deep cycle batteries Filler Cap Batteries Filler cap batteries are lead-acid with a high degree of antimony in the grid alloy. Semi-maintenance Free Batteries Servicing is reduced in the semi-maintenance free batteries due to reduced amount of antimony in the grid alloy. All information subject to change without notice. then transfers the mechanical energy to the engine as a rotational force. The recommended battery carrier designs are: Top crossbar Top mid-frame Top picture frame Angled J-bolt 10-4 All information subject to change without notice. 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . The battery carrier may be heated or cooled to keep the battery at optimum operating temperature. road splash and other environmental conditions.8 C) Above 32 F (0 C) Below 32 F (0 C) 2100 2800 MBE 4000 12V Table 10-1 Minimum Battery Capacity for Acceptable Engine Cranking Battery Mounting and Location Battery mounting boxes.ELECTRICAL SYSTEM Battery Capacity The minimum battery capacity recommended for acceptable engine cranking is listed in Table 10-1. 27 C (80 F). or carriers support the batteries and protect them from excess vibration. Minimum Battery Ratings Engine Model System Voltage SAE Cold Cranking AMPS (CCA) @ 0 F (-17. Figure 10-2 Battery Retainers All information subject to change without notice. 10-5 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION .MBE 4000 APPLICATION AND INSTALLATION See Figure 10-2. 10. Batteries mounted between frame rails.2. wear protective clothing. When the engine starts. road splash. Batteries mounted outside.ELECTRICAL SYSTEM Battery Explosion and Acid Burn To avoid injury from battery explosion or contact with battery acid. When the engine start circuit is closed. Flush your eyes with water. The cranking motor drive pinion and the engine flywheel ring gear must be matched to provide positive engagement and to avoid clashing of the gear teeth. NOTICE: To prevent excessive overrun and damage to the drive and armature windings. 10-6 All information subject to change without notice. the cranking motor is equipped with an overrunning clutch within the drive pinion. and dirt but as close as possible to the starting motor. experience greater vibration. Get medical attention immediately. The battery should be located away from flame or spark source. it is necessary to disengage the drive pinion to prevent the armature from overspeeding and damaging the cranking motor. Cantilever battery mountings are not recommended. Both of these locations are recommended for all applications.2 CRANKING MOTOR The cranking motor is bolted to the flywheel housing. A cranking period should not exceed 30 seconds without stopping to allow the cranking motor to cool for at least two minutes. a drive pinion on the armature shaft engages with the teeth on the engine flywheel ring gear to crank the engine. the switch should be opened immediately when the engine starts. either inside or above the rails. but close and parallel to frame rails. If you come in contact with battery acid: Flush your skin with water. 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . Apply baking soda or lime to help neutralize the acid. The battery should be located in a place with minimum vibration and easy access for visual inspection and maintenance. work in a well ventilated area. and avoid sparks or flames near the battery. To accomplish this. experience minimum vibration. with one in the commutator end cap. Bronze Bearing 16. Seamless. Shift Mechanism (Totally Enclosed) 11. 1. 10-7 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . O-ring 2. Low Friction Bushing 7. Shaft Seal 18. Sealing Boot 10. One-piece Brush Figure 10-3 Typical Cranking Motor Cross-section Excessive engine cranking may cause the starter to overheat and may reduce its life. O-ring 9. End Cap (Removal for Inspection) 3. Two-piece Housing 12.MBE 4000 APPLICATION AND INSTALLATION The starter motor armature is supported by three centered bronze bearings located. Gasket 6. in the nose and intermediate housings. All information subject to change without notice. Connector Strap 5. Bronze Bearing 4. Bronze Bearing 14. See Figure 10-3. O-ring 17. one each. Heavy-duty Drive Overrunning Clutch 15. O-ring 13. One-piece Solenoid Case 8. with a two minute cool down interval between cranking periods. 10. 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . as a result. incorrect alternator output. Even though these alternators are referred to as ‘‘one wire systems". Modern battery charging alternators are three phase AC machines with solid state.ELECTRICAL SYSTEM Cranking time should not exceed 30 seconds. a separate ground return line should be used from the alternator to the battery. The MBE 4000 alternator is typically front-mounted and driven Refer to section for accessory drive information. relying on the frame for ground return can result in incorrect voltage sensing by the regulator and.2. self-contained rectifiers and regulators. The alternator also supplies sufficient current to carry any other electrical load requirements up to the rated capacity of the alternator.3 ALTERNATOR The battery-charging alternator provides a source of electrical current for maintaining the storage battery in a charged condition. Because the regulator is contained within the alternator. 10-8 All information subject to change without notice. or other alternator components. Anchor the adjusting strap and mounting brackets to a rigidly fixed heavy section. The cable size should be the same as the supply cable coming from the battery.4 GROUNDING REQUIREMENTS The preferred method of ground return is to use a copper cable from the ground side of the cranking motor or alternator back to the battery. Society of Automotive Engineers (SAE) recommended practice should be followed with respect to pulley alignment and tolerances. Incorrect mounting can result in: Improper alignment of pulleys Excessive vibration of mounting assembly components Improper alignment of pulleys causes excessive belt or pulley wear. 10. 10-9 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . The pulley groove must be concentric with the bore and the pulley should be adequately balanced. the distance from the battery to the cranking motor or alternator as well as the ground return distance must be used to determine the total cable resistance or system voltage drop. Excessive vibration of mounting assembly components can cause failure of the mounting bracket. The following guidelines are provided for correct alternator mounting: NOTICE: Do not mount the alternator near the exhaust manifold.2. An effective bracket must stay firmly attached to the engine. an adjusting strap and the associated hardware. A mounting location not subject to resonant vibration is best.MBE 4000 APPLICATION AND INSTALLATION Alternator Mounting A Typical alternator is now head-mounted. Contact the belt manufacturer if belt resonance is a problem. the adjusting strap. Provision must be made for belt tension adjustment. The typical mounting assembly includes a mounting bracket that matches the alternator mounting bolts. Belt resonance will result in short belt life. the alternator mounting lugs. A belt tensioner is used to keep the drivebelt in proper tension. Mounting near the exhaust manifold could overheat the alternator and the regulator. Drive and driven pulleys must be in parallel and angular alignment to prevent short belt life or loss of belt. Motion between the mounting bracket and adjusting strap can create an unacceptable vibration. When calculating the correct cable size. Fabricated sheet metal pulleys are not recommended for applications with heavy belt loads. All information subject to change without notice. A mounting location close to the engine block minimizes mounting bracket overhang. The alternator mounting assembly should support the alternator rigidly so that the alternator pulley grooves are in the same plane as the driving pulley grooves on the engine. Good cable routing is not too tight or loose. loom or conduit requirements and connections. Conduit or loom should be considered to protect cable where extreme heat or abrasion cannot be avoided. Die-cast lead alloy terminals are recommended for post-type batteries.5 WIRING Cables and wiring are an important part of the electrical system which is often overlooked or neglected. batteries used and location. A full copper circuit is recommended for all installations because it maintains the lowest resistance and is the most trouble free. and to relieve strain at battery and motor terminals. around corners and other stress points. Frame area where ground connection is made should be stripped of paint and tinned to prevent corrosion. Ring terminals are not recommended for battery connections but are recommended for other connections. The cables are the highway on which the electrical energy travels.2. Sealed terminals are recommended where sealed terminal batteries are available.ELECTRICAL SYSTEM 10. 10-10 All information subject to change without notice. Cranking the engine on a cold morning with a faulty or dirty connection which restricts the flow is the same as rush hour on a suddenly reduced highway. system voltage. insulation. Clamps should be used to support the battery cable every 24 in. routing clamps. That information is then used to determine proper routing. cable length and size. Use for following guidelines for electrical wiring: Rope stranded copper cable is recommended for #0 or larger cable sizes because of its added flexibility. starting motor type. abrasion and vibration. and avoids excessive heat. As long as traffic is light there is no problem but during rush hour it is quite different. is properly supported. Just one faulty or dirty connection can reduce electrical energy transfer just as surely as traffic on a modern four lane highway that is narrowed to one lane. Guidelines for Electrical Wiring Guidelines for electrical wiring start with determining the vehicle or chassis type.. 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . terminals. Recommended battery cable connections to the frame have hardened steel flat washers with a locking nut. External or internal tooth lock washers are not recommended for battery cable electrical connections. Once you have the voltages: Battery Voltage minus Motor Voltage equals Cable Loss. Adjust the load to 500 amps (250 amps if a 24 V system). Repeat if there is a second battery box. NOTE: If the system to be tested normally operates on straight 24 V it will be necessary to temporarily reconnect the system to 12 V. Turn off load. 2. If the system is a combination 12/24 V system using a series-parallel switch or a T/R alternator. Connect the battery cables within the battery box and tighten to specification. 5. Measure voltages for correct sizing as follows: 1. Connect voltmeter to the solenoid “BAT” terminal and starter ground. Connect directly to terminals. Reconnect a straight 24 V system to 12 V as follows: 1. 3. 7. 9. Connect the negative incoming cable (ground) to the negative (-) terminal of the same battery. Quickly measure voltage of a connected battery (measure at a terminal nut or actual post). 3. Do not connect a carbon pile to a 24 V source. do NOT use this procedure. All information subject to change without notice. 4. not to load clamp. Disconnect all batteries in the 24 V box. Tighten nuts holding battery cables to solenoid and starter terminals. Connect the positive carbon pile lead to the starter solenoid “BAT” terminal. allow carbon pile to cool. Now the battery system is 12 volts. 10. Measure motor voltage.MBE 4000 APPLICATION AND INSTALLATION Cable Loss Test Procedure Correct sizing and installation can be checked by measuring voltages. One (1) good 12 V battery is all that needs to be connected in the battery box. Connect the incoming positive (+) cable to the positive (+) terminal of one 12 V battery. Connect the negative lead to the starter ground terminal. 4. NOTE: Solenoid “BAT” terminal is at battery voltage when batteries are connected. Mark cable ends. Turn off load. 6. Reconnect back to 24 V before using the vehicle. 8. 10-11 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . Adjust load to 500 amps (250 amps if a 24 V system). The circuit resistance method should be used. 2. If the measurement exceeds the maximum values (see Figure 10-4).0001 ohms resolution) and read the resistance. or increasing wire gage will have to be taken. disconnect positive and negative cables at the battery. resistance should be less than the maximum allowable for this system.ELECTRICAL SYSTEM Measuring Circuit Resistance To measure cranking circuit resistance. corrective measures such as cleaning the connections. Install a galvanometer or precision ohmmeter (0. 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . reducing the number of connections. Figure 10-4 Cable Resistance 10-12 All information subject to change without notice. If this total resistance exceeds the value listed in Table 10-2. circuit resistance may be estimated as follows: 1. Use the chart (see Figure . 5.00075 ohm 0. corrective action must be taken.0002 ohms for any contactors in the circuit.0012 ohm 0. 10-4) to estimate cable resistance. Count the number of connections in circuit. 6. 4.10 ohm Table 10-2 Maximum Circuit Resistance All information subject to change without notice.00001 ohms.030 ohm Circuit Resistance 0. Measure the total length of the cable from the battery to the starter and back to the battery. Add this number to the cable resistance number found in step 2. 2. Multiply the number of connections by 0. Magnetic Switch and Series-Parallel Circuit 12 V system 24 V system Solenoid Switch Circuit 12 V system 24 V system Starting Motor Circuit 12 V system 12 V high output system 24 V system 0. Also add 0.0067 ohm 0. 10-13 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION . 3.002 ohm 0.048 ohm 0.MBE 4000 APPLICATION AND INSTALLATION Calculating Circuit Resistance If a galvanometer is not available. ELECTRICAL SYSTEM THIS PAGE INTENTIONALLY LEFT BLANK 10-14 All information subject to change without notice. 7SA250 0403 Copyright © 2004 DETROIT DIESEL CORPORATION .